«•■ i »: ,Vk^ .^''^Iv THE '^tf^/y^rttl. HAND-BOOK OF ARTILLERY, FOR THE SERVICE OF THE UNITED STATES, (APvMY AND MILITIA.) BY CAPT. JOSEPH ROBERTS. 4th Regt. Art. U. S. akmt. {( SECOND EDITION, REVISED AND ENLARGED. / CHARLESTON : EVANS &, COGSWELL, PRINTERS. 1862. ^•^^•^t*' P E O C E E D I N (i S . The following Report was made by the Committee ap- pointed at a meeting of the staff of the Artillery School at Fort Monroe, Va., to whom the commanding officer of the School had referred this work : Your Committee to which has been referred the consid- eration of the work of Captain Roberts, proposed as a text-book for the Artillery School, beg leave to submit the following Report, viz : The work submitted by Captain Roberts, and entitled '^Hand-Book of Artillery," embraces sections on the fol- lowing subjects : [For subjects see Table of Contents, page 7.] Under each of these heads, except the last, the work contains a number of questions and answers. Your Com- mittee have carefully examined each of these (juestions and their corresponding answers, and find that the an- swers have been principally drawn from the following sources, viz : Gibbon's Artillerist's Manual, Light and Heavy Artillery Tactics, and the Ordnance Manual, all of which works have been authorized by the War Depart- ment. Wherever the prescribed authorities furnish the means of answering the questions, they appear to have been followed as closely as possible. In the opinion of your Committee, the arrangement of the]^ subjects and the selection of the several questions 4 PROCEEDINGS. and answers have been judicious. The worlc is one which may be advantageously used for reference by the officers, and is admirably adapted to the instruction of noncom- missioned officers and privates of Artillery. Your Committee do therefore recommend that it be sub- stituted as a text-book in place of "Burns' Questions and Answers on Artillery." (Signed) I. VOGDES, Capt. 1st Art'y. (Signed) E. 0. C. ORD, Capt. 3d Art'y. (Signed) J. A. HASKIN, BvT. Maj. and Capt. 1st Art'y. The preceding Report was adopted, and the stafiF I'eeom- mended this work as a book of instruction at the Artillery School, in lieu of " Burns' Questions and Answers on Ar- tillery." PEEFACE TO SECOND EDITION The following compilation was prepared for the instruc- tion of noncommissioned oflBcers and privates of the Ar- tillery School, where it is now in successful use as a text- book. Much of the matter is taken from Burns' Questions and Answers on Artillery, Gibbon's Artillerist's Manual, Heavy Artillery Tactics, the Ordnance Manual, and Kings- bury's Artillery and Infantry. In the preface to the first edition, the compiler inad- vertently omitted to acknowledge his indebtedness to the l^roof-sheets of a forthcoming work on Ordnance and Gunnery, by Captain Benton, for a portion of the matter of the Appendix on Rifle cannon. The compiler is under great obligations to several of his brother officers at Fort Monroe (especially to Major Haskin, 1st Artillery), for their kindness in assisting him in the compilation of this little volume, and for impor- tant suggestions in the revision of many of the ''answers.'.' Fort Monroe, Va., 1861. Digitized by tine Internet Arciiive in 2010 witii funding from Dul Machines, 134 XIII. Practical Gunnery, . . . .162 XIV. Miscellaneous, 167 Appendix — Rifle Cannon, * 180 Index, 186 THE HAND-BOOK OF ARTILLERY. Part I. Section I. ARTILLEEY IN GENERAL. 1. What is understood by the term artil- lery? Heavy jDieces of every description, with the implements and materials necessary for their use. 2. Moiv 7nany kinds of pieces are employed in the land service of the tfnited States ? Four, viz : Guns, Howitzers, Columbiads and Mortars. 3. How are these distinguished ? According to their use, as Sea-coast, Gar- rison, Siege and Field Artillery. 4. What metals are used in their construc- tion ? All heavy pieces, such as those for sea- coast, siege and garrison equipment, are made of iron ; and those for field service, of bronze. 5. What is bronze for cannon ? An ALLOY consisting of 90 parts of copper and 10 of tin, allowing a variation of one part of tin more or less. It is commonly called brass. 10 HAND-BOOK OF ARTILLERY. 6. Why is bronze used in preference to iron, for field pieces P This metal having greater tenacity and streiiixtli thf^n iron, the pieces can be made lighter. 1. In luhat respect does iron merit a prefer- ence ? Iron is less expensive than bronze, and is more capable of sustaining long-continued firing with larger charges; such picce>5 are, therefore, better calculated for the constant heav}^ firing of sieges. Note.— In tbe sieges in Spain, bronze guns could never support a heavier tire than 120 rounds in twenty-four hours, and were never used to batter at distances exceeding 300 yards; whereas, with iron guns, three times that num- ber of rounds were fired with eftect, from three times the distance, for several consecutive days, without any other injury than the enlargement of their vents. The compara- tive power of conducting heat in iron and copper being respectively as 3.743 to 8.932, taking gold at 10.000, it is evident that in practising with iron and bronze pieces of the same calibre, it would soon become necessary to reduce the charges in the bronze pieces, and, also, to increase the time b-'tween the discharges, to prevent their softening and drooping ; while with iron, full charges and rapid firing may be kept up. 8. What additional ohjectioji has been urged to bronze for cannon ? The difficulty of forming a perfect alloy, in consequence of the difi'erence of fusibility of tin and copper. 9. What iron jneces are used in the land service ? 12, 18 and 24-pdr. siege and garrison guns, 32 and 42-pdr. sea-coast guns, 8-in. siege and 24-pdr. garrison howitzers, 8 and 10-in. sea- ARTILLERY IX GENERAL. 11 coast howitzers, 8 and 10-in. columbiads,"^ 8 and lU-in. seige, and 10 and 13-in. sea-coast mortars. Note. — The 24-pdr. eprouvette is also of iron, and used for the proof of powder. 10. What are the lands of bronze pieces in use at present ? 6 and 12-pdr. field guns; 12-pdr. mountain howitzer ; 12, 21 and 82-pdr. field howitzers ; stone and 24-pdr. Coehorn mortars. 11. ^yhat is a battery ? This term is applied to one or more pieces, or to the place where the}^ are served. 12. What regulates the dimensions of a piece? Its calibre and the tenacity and elasticity of the metals employed in its fabrication. Its thickness must be proportioned to the eftect developed by the powder; and the length is determined by experiment, and should not exceed 24 calibres. The exterior surface of a cannon is composed of several surfaces, more or less inclined to the axis of the bore, the forms of which have been determined by exi^eriment. 13. Why is a piece made stronger nectr the breech than toward the muzzle? Because the elastic lorce of the inflamed gunpowder is there greatest, constantly di- minishing in intensity as the space increases in which it acts. 14. What is the length of a piece ? *" Those of the new 2^(ater?i are denominated 64 and 128-pdrs. 12 nAND-BOOK OF ARTILLERY. The distance from the rear of the base- ring to the face of the piece. 15. What is the extreme length^ From the rear of the cascable to the face. 16. What is the bore of a piece f It includes the part bored out, viz : the cylinder, the chamber (if there is one), and the conical or spherical circle connecting them. 17. What is understood by the calibre of a piece ? The diameter of the bore. 1(S. How do you ascertain the number of calibres in a piece ? Divide the length of the c^^linder, in inches, by the number of inches in the cali- bre. 19. The number of calibres being known, hoic do you find the length of the cylinder ? Multiply the number of calibres by the calibre in inches. 20. What is meant by the sights of apiece ? Artificial marks on the piece for determin- ing the line of fire, 21. How are the sights determined? Usually by means of the gunner's level, when the trunnions are perfectly horizontal. 22. What is the line of metal or the natu- ral line of sight ? A line drawn from the highest point of the base-ring to the highest point on the swell of the muzzle. 23. What is the axis of a piece ? The central line of the bore. ARTILLERY IN GENERAL. 13 24. What is the natural angle of sight? The angle which the natural line of sight makes with the axis of the piece. 25. What is the dispart of a piece ? It is the difference of the semi-diameter of the base-ring and the swell of the miiz-zle, or the niiizzle-band. It is, therefore, the tangent of the natural angle of sight to a radius equal to tlie distance from the rear of the base-ring to the highest point of the swell of the muzzle, or the front of the muzzle-band, as the case may be, measured parallel to the axis. 26. Crive the nomenclature of a apiece. The CASCABLE is the part of the gun in rear of the base-ring, and is composed generally of the knob, the neck, the fillet and the base of the breech. The BASE OF THE BREECH is a frustum of a cone, or a spherical segment in rear of the breech. The base-ring* is a projecting band of metal adjoining the base of the breech, and connected with the body of the gun by a concave moulding. The breech is the mass of solid metal behind the bottom of the bore, extending to the rear of the base-ring. The reinforce is the thickest part of the body of the gun, in front of the breech ; if there be more than one reinforce, that which -•• This has been dispensed with in the brass I2-pdr. of the new pattern (the Napoleon gun), and in the new-model columbiads. 9 14 HAND-BOOK OF ARTILLERY. is next the breech is called the first reinforce; the other the second reinforce. The REiNFORCE-BAND is at the juiKtion of the first and second reinforces, in the heavy howitzers and cohimbiads. The CHASE is the conical part of tlie gun in front of the reinforce. The ASTRAGAL AND FILLETS in field guns, and the chase-ring in other pieces, are the mouldings at the front end of the chase. The NECK is the smallest part of the piece in front of the astragal or the chase-ring. The SWELL OF THE MUZZLE is the largest part of the gun in front of the neck. It is terminated by the miizzle-^nouldings, which, in field and siege guns, consist of the lip and fillet. In sea-coast guns, and heav}^ howit- zers and columbiads, there is no fillet. In field and siege howitzers, and in mortars, a rnvzzle-band takes the place of the sic ell of the muzzle. The FACE of the piece is the tei-minating plane perpendicular to the axis of the bore. The TRUNNIONS are cylinders, the axis of which are in a line perpendicular to the axis of the bore, and in the same plane with that axis. The RiMBASES are short cylinders uniting the trunnions with the body of the gun. The ends of the rimbases, or the shoulders of the trunnions, are planes perpendicular to the axis of the trunnions. The BORE of the piece includes all the part bored out, viz : the cylinder, the cham- ARTILLERY IN GENERAL. 15 bey. (if there is one), and the conical or spherical surface connecting them. The CHAMBER in howitzers, columbiads, and mortars, is the smallest part of the bore, and contains the charge of powder. In the howitzers and columbiads,* the chamber is cylindrical; and is united with the large cylinder of the bore by a conical surface ; the angles of intersection of this conical surface with the cylinders of the bore and chamber, are rounded (in profile) by arcs of circles. In the 8-in. siege howitzer, the chamber is united with the cylinder of the bore by a spherical surface, in order that the shell may, when necessarj^, be inserted with- out a sabot. The BOTTOM OF THE BORE (to facilitate sponging) is a plane perpendicular to the axis, united with the sides (in profile) by an are of a circle the radius of which is one- fourth the diameter of the bore at the bottom. In the columbiads, the heavy sea- coast mortars, stone-mortar, and eprouvette, the bottom of the bore is hemispherical. The MUZZLE, or mouth of the bore, is cliamfcred to a depth of 0.15 inch to 0.5 inch (varying with the size of the bore), in order to prevent abrasion, and to facilitate loading. The TRUE WINDAGE is the difference be- tween the true diameters of the bore and of the ball. * The new columbiad is made without a chamber. 16 HAND-BOOK OF ARTILLERY. 27. What is the vent P The aperture tlirouTee. B}^ placing tlie axis of the piece liorizontal, and marking the breech at anj- one of the divis- ions on the arc, an}^ elevation or depression required will be noted hj the number of de- grees below or above this mark. It turns on a pivot which admits of the arc, when not in use, being placed inside the cheek to which it is attached. 48. What is the use of the knob of the casca- ble ? To faeilitate the handling of the piece in mounting and dismounting it, and moving it when off its carriage. 44. Of what use are the trunnions of a piece? . By means of them the piece is attached to its carriage; and by being placed near the centre of gravity, it is easily elevated or depressed. 45. What are the dolphins of a piece ? Two handles placed upon the piece, with their centres over the centre of gravity, by which it is mounted or dismounted. 46. Are all pieces provided ivith dolphins ? Only the 12-pdr. brass guns,' and the 24 and 8:^-pdr. brass howitzers. 47. What is understood by the preponder- ance of a piece ? It is the excess of weight of the part in rear of the trunnions over that in front; it is measured by the lifting force in pounds, which must be applied at the rear of the base-ring to balance the^iece when suspend- ed freely on the axis of the trunnions. <^^ ARTILLERY IN GENERAL. 21 48. Why is this preponderance given? To prevent the sudden dipping of the muz- zle in firing, and violent concussion on the carriage at the breech. 49. What is bushing a piece of artillery ? Inserting a piece of metal about an inch in diameter (near the bottom of the bore), through the centre of which the vent has been previously drilled. It is screwed in. 50. What kind of metal is used for bushing bronze pieces? Pure copper always, which is not so liable to run from heat as gun-metal. 51. What is the object of bushing a piece? To prevent deterioration of the vent, or provide a new one when this has already occurred. 52. Is all new artillery bushed ? No, only bronze pieces, and iron pieces only when repeated firing has rendered it absolutel}^ necessary. 53. How is artillery rendered unserviceable? I. Drive into the vent a jagged and hard- ened steel sjDike with a soft point, or a nail without a head -, break it off flush with the outer surface, and clinch the point inside by means of the rammer. II. Wedge a shot in the bottom of the bore by wrapping it with felt, or by means of iron wedges, using the rammer or a bar of iron to drive them in. III. Cause shells to burst in the bore of bronze guns. IV. Fire broken shot from them with large charges. 3SZ HAND-BOOK OF ARTILLERY. y. Fill the piece with sand over the charge, to burst it. VI. Fire a piece against another, muzzle to muzzle, or the muzzle of one to the chase of the other. VII. Light a fire under the chase of a bronze gun, and strike on it with a sledge to bend it. VIII. Break off the trunnions of iron guns; or burst them by firing them at a high elevation, with heavy charges and full of shot. 54. State how to iinspike a piece ? If the spike is not screwed in or clinclied, and the bore is not impeded, ])ut in a charge of powder ^ of the weight of the shot, and ram junk wads over it ; laying on the bot- tom of the bore a slip of wood, with a groove on the under side containing a strand of quick-match, by which fire is communicated to the charge. In a brass gun, take out some of the metal at the upper orifice of the vent, and pour sulphuric acid into the groove, and let it stand some hours before firing. If this method, several times re- peated, is not successful, unscrew the vent- jDiece if it be a brass gun; and if an iron one, drill out the spike, or drill a new vent. 55. Exjdain how to drive out a shot wedged in the bore ? Unscrew the vent-piece, if there be one, and drive 'in wedges so as to start the shot forward ; then ram it back again in order to seize the wedge with a hook ; or .pour in ARTILLERY IN GENERAL. 23 powder, and fire it after replacing the vent- piece. In the last resort, bore a hole in the bottom of the breech, drive out the shot, and stop the hole witli a screw. 56. What is scaling a piece of artillery? Flashing off a small quantity of powder to clean out the bore; about yV of the sliot's weight. The practice is discontinued. 57. How are cannon in our service marked ? As follows, viz. : The runnber of the gun and the initials of the insjjector's name on the face of the muzzle — the numbers in a sepa- rate series for each kind and calibre at each foundry; the initial letters of the' name of the founder, and of the foundry, on the end of the right trunnion ; the year of fabrication on the end of the left trunnion; the foundry number on the . end of the right rimbase, above the trunnion; the weight of the piece in pounds on the base of the breech; the letters U. S. on the upper surface of the piece, near the end of the reinforce. " 58. What marks are used to designate con- demned pieces ? Pieces rejected on inspection are marked X C on the face of the muzzle; if condemn- ed for erroneous dimensions which cannot be remedied, add X D ; if by powder proof, X. P; if^by water proof, X W. 59. What are the kinds of proof which artil- lery must undergo, before being received into the service ? Ist. They are gauged as to their several dimensions, internal and external; as to '24 HAND-BOOK OF ARTILLERY. justness and position of the bore, the cham- ber, vent, trunnions, etc. 2d. They are fired with a regulated charge of powder and shot, being afterwards searclied to discover irregularities or holes produced by the tiring. 3d. By means of engines, an endeavor is made to force water through them. 4tli They are examined internalh', b}' means of light reflected from a mirror. 60. A7'e brass cannon liable to external in- jury, caused by service ? They are little subject t9 such injury, ex- cept from the bending of the trunnions sometimes, after long service or heavy charges. Note. — Recent experiments at Fort Monroe show that brass guns, when rifled, and fired with large charges and heavy shot, expand so much that the projectile does not take the grooves. 61. What are the causes of internal injury? Internal injuries are caused by the action of the elastic fluids developed in the com- bustion of the powder, or b}' the action of the shot in passing out of the bore. 62. Name the injuries of the first kind. Enlargement of the bore by the compression of the metal ; corrosion of the metal at the inner orifice of the vent, or at the mouth of the cylindrical chamber -, cracks, from the yielding of the cohesion of the metal ; cavi- ties, cracks enlarged by the action of the gas, and by the melting of the metal, ob- servable especially in the upper surface of the bore. ARTILLERY IN GENERAL. 25 63. Name those of the second kind. The lodgment of the shot — a compression ,of the metal on the lowef side of the bore, at the seat of the shot, which is caused by the pressure of the gas in escaping over the top of the shot. There is a corresponding hi7r in front of the lodgment; and the mo- tion thereby ^iven to the shot causes it to strike alternately on the top and bottom of the bore, producing other enlargeme?its, gen- erally three in number:, the first on the upper side a little in advance of the trun- nions; the second, on the lower side about the astragal; the third, in the upper part of the muzzle ; it is chiefly from this cause that brass guns become unserviceable. Scratches, caused b}^ the fragments of a broken shot, or the roughness of an imperfect one; en- largement of the muzzle by the striking of the shot in leaving the bore; external cracks, or longitudinal slits, caused by too great a compression of the metal on the inside. 64. Wheji is a piece said to be honeycombed f When the surface of the bore is full of small holes and cavities. 65. To what is this due ? To the melting and volatilization of a portion of the tin in the alloy: tin being much more fusible than copper. 66. Bo LODGMENTS causc a.n inaccuracy of ■fire? They do. 67. How may this in a measure be remedied ? Ey using a wad over the cartridge, in 3 26 HAND-BOOK OF ARTILLERY. order to change the place of the shot; or by Avrapping the shot in woolen cloth or paper, so as to diminish the windage. In field guns, the paper cap which is taken off the cartridge should always be put over the shot. 68. To what injuries are iron cannon subject ? To the above defects in a less degree than brass, except the corrosion of the metal, by which the vent is rendered unserviceable from enlargement. The principal cause of injury to iron cannon is the rusting of the metal, producing a roughness and enlarge- ment of the bore, and an increase of any cavities or honeycombs which may exist in the metal. 69. How may you judge of the service of an iron gun ? Generally by the appearance of the vent. 70. Whit rules are laid down for the pre- servation of artillery ? Cannon should be placed together, accord- ing to kind and calibre, on skids of stone, iron, or wood, laid on hard ground well rammed and covered with a layer of cinders or of some other material to prevent vege- tation. In case of guns and long howitzers, the pieces should rest on the skids in front of the base-ring and in rear of the astragal, the axis inclined at an angle of 4° or 5° with the horizon, the muzzle lowest, the trunnions touching each other; or the trun- nion of one piece may rest on the adjoining piece, so that the axis of the trunnions may ARTILLERY IN GE>^ERAL. 2 1 be inclined about 45° to the iiorizon ; the vent down, stopped with a greased wooden plug, or with putty or tallow. The pieces may be piled in tAvo tiers, with skids ])laced between them exactly over those which rest on the ground; the nluzzles of both tiers in the same direction, and their axis pre- serving the same inclination. In case of short howitzers and mortars, the pieces should stand on their muzzles, resting on thick planks, the trunnions touching, the vents st0])ped. 71. What^ additional j^recaw/^o;! shoidd be observed in ease of iron pieees. They should be covered on the exterior with a lacker impervious to water; the bore and the vent should be greased with a mix- ture of oil and tallow, or of tallow and beeswax melted together, and boiled to expel the water. The lacker should be renewed as nften as necessary, and the grease at least once a year. The lacker and grease should be applied in hot weather. The cannon should be frequently inspected, to see that moisture does not collect in the bore. 28 5IAND-B00K OF ARTJLLERY. Part I. Section II. ON GUNS. 1. What are Guns ? Long cannon without chambers. 2. JIoiv are guns denominated ? By the weight of their respective shot. 3. What are the p'incipal parts of a gun ? The cascable, breech, reinforce, chase, and muzzle. 4. What p'oportion usually exists between the length and calibre of a gun? It varies from 15 to 23 calibres. 5. What projjortion does the dispart of a gun bear generally to its length ? About a sixtieth part in field guns, about a thirtieth part in sea-coast, and about a thirty-eighth part in siege and garrison guns. 6. What is the natural a^igle of sight in siege and garrison guns ? One degree and thirty minutes. 7. What is it infield guns ? One degree in all except the new 12-pdr., in which it is one degree and six minutes. 8. Why have sea-coast guns no natural line of sight? Because the swell of the muzzle is not visible when the e^^e is on a level with the base-rino-. GUNS. 29 9. Upon- what are guns mounted ? On field, siege, barbette or casemate car- riages. 10. What projectiles are used ivith guns ? Solid shot, spherical-case, grape, and can- ister. n . About what are the weights of the differ- ent guns ? 6-pdr., 884 lbs.; brass 12-pdr., 1,757 lbs., new pattern 1,220 lbs.; iron 1^-pdr., 3,590 lbs.; 18-pdr., 4,913 lbs.; 24-pdr., 5,790 lbs.; 3a-pdr., 7,200 lbs.; 4S-pdr., 8,465 lbs. 12. Give the entire length of the several guns. 6-pdr. field gun, 65.6 inches ; 12-pdr. field gun, 85 inches, new pattern 72.15 inches ; IS-pdr. iron gun, 116 inches; 18-pdr., 123.- 25 inches; S^4-pdr., 124 inches; 3^-pdr., 125.2 inches ; 4^-pdr., 129 inches. ^ HAND-BOOK OF ARTILLERY. Part I. Section III. 1. What is a Howitzer ? A chambered j^iece, of larger calibre than a gun of like weight, and mounted in a sim- ilar manner. 2. What form of chamher is given to howit- zers ? That of a cylinder. 3. How is it united with the large cylinder of the bore ? By a conical surface, except in the 8-inch siege howitzer, where it is united with the cylinder of the bore by a spherical surfiice, in order that the shell may — when neces- sary — be inserted without a sabot. 4. What advantages are gained by the em- ployment of howitzers ? They project larger shells than the guns with which they are associated, are well adapted for ricochet fire, the destruction of field-works, breaking down palisades, and setting fire to buildings. 5. What projectiles are used with howitzers? Shells, usually; spherical-case, canister, grape and carcasses. HOWITZERS. 31 fe. Give the entire length of the several how- itzers. Iron 10-inch, 124.25 inches; 8-inch sea- coast, 109 inches; 8-inch siege and garrison, 61.5 inches; S4:-pdr. garrison, 69 inches; 33-pdr. field, 82 inclies ; a4-pdr. field, 71.2 inches; IS-pdr. field, 58.6 inches; mountain 13-pdr., 37.21 inches. 7. What is the weight of a howitzer of each land? 10-inch, 9,500 lbs. ; 8-inch sea-coast, 5,740 lbs. ; 8-inch siege and garrison, 2,614 lbs. ; S4-pdr. garrison, 1,476 lbs.; 32-pdr. field, 1,920 lbs.; S4-pdr. field, 1,318 lbs.; 12-pdr. field, 788 lbs. ; 12-pdr. mountain, 220 lbs. 8. Wliat is the natural angle of sight in siege and garrison and field howitzers ? One degree. 9. ^Vhat in mountain howitzers ? Thirty-sevcii minutes. 10. Why have sea-coast howitzers no natural line of sight ? Because the swell of the muzzle is not visible when the eye is on a level with the base-ring. 32 HAND-BOOK OF ARTILLERY. Part I. Section IY. ON COLUMBIADS. 1. What is a Columbiad ? A gun of much larger calibre than the ordinary gun, used for throwing solid shot or shells. 2. What are some of the peculiarities of this gun when mounted in barbette f Its carriage gives a vertical field of fire from 5° depression to 39° elevation ; and a horizontal field of fire of 360°. 3. Are these pieces chambered ? Those of the old pattern have chambers ; but they are now made without any. 4. Give the loeight of this piece. Old Pattern IO-inch, 15,400 lbs. j 8-inch, 9,240 lbs. New Pattern lS8-pdr., 15,000 lbs.; 64-pdr., 9,100 lbs. 5. What is the entire length of this gun ? 10-inch, 126 inches; 8-inch, 124 inches; 138-pdr., 132.6 inches; 64-pdr., 128.8 inches. 6. What is the natural angle of sight in this piece ? 8-inch, 1° 23'; 10-inch, 1° 21'; 128-pdr., 2° 45'; 64-pdr., 2° 30'. MORTARS. 33 Part I. Section Y. ON MOETAKS. 1. What is a Mortar ? The shortest piece in service; the trun- nions are phxced in rear of the vent at the breech; the bore is very Large in proportion to the length, and is provided with a cham- ber. 2. What are the principal advantages ob- tained by the employment of mortars ? Eeaching objects by their vertical fire — such as a town, battery, or other place — whose destruction or injury cannot be ef- fected by direct or ricochet fire ; disniQunting the enemy's artillery; setting fire to and overthrowing works ; blowing np maga- zijies; breaking through the roofs of bar- racks, casemates, etc.; and producing havoc and disorder amongst troops. 3. What do you mean by vertical fire ? That produced by firing the mortar at a high elevation. 4. What are its advantages ? The shell having attained a great eleva- tion, descends with great force on the object, in consequence of the constant action of the force of gravity on it. 5. Why are mortars constructed stronger and shorter than other pieces ? 34 HAND-BOOK OF ARTILLERY. Because greater resistance is required in consequence of the higli elevation under which tiiey are fired; and were tlK\y h:)nger, the diflicuity experienced in loading them would become too great. 6. Why is a mortar constructed with a cham- ber? In consequence of employing various charges, some very small, it becomes neces- sary to use a chamber to concentrate the charge as much as possible, so that the shell may be acted on by the entire expansive force of the powder. 7. What form of chamber is given to mor- tars ? Usually that of a frustum of a cone. The bottom is hemispherical in the sea-coast, stone and eprouvette mortars. In siege mortars it is a plane surfjice, the angles of intersection being rounded in protilc by arcs of circles. 8. What is this form of chamber called f Gomer Chamber. 9. What is the advantage of the conical over the cylindrical chamber ? Cylindrical chambers are objectionable, as the projectile is frequently broken in conse- quence of the small surface exposed to the action of the charge. This defect is obviat- ed by large chambers, and particularly by those that are conical, in wdiich the charge is expended upon nearly a hemisphere. 10. What form of chamber has the eprou- vette ? ' i T> .. i/r -^ y one or more of each. Battery- \\ a gons j Spare spoke's, 50 to each battery ^ Spare fellies, 20 to each battery (in store- Spare harness 1 ^^ l ^^^^g^'^^. Horse shoes and nails j boxes, j G-unpowder, saltpetre, sulphur, charcoal, la- boratory-paper, cannon-primers (percussion and friction), fuzes and plugs for field ser- vice, stuff' for cartridge-bags, woollen yarn, cotton yarn, glue. 13. Are any other pieces ever used for field service? Yes; sometimes the 12 and 18-pdr. siege guns and the S-in. siege howitzer. 14. For luhat particidar service are these different pieces most suitable ? The siege pieces for batteries of position; the 12-pdr. battery for the following move- ments of infantry, and the G-pdr. battery for those of cavalry. Note. — These siege pieces should bo placed on the weak- est points of a line, and on heights which either form a key to the position, or from whence the greatest and longest continued effect may be produced. 15. What are the peculiar advantages of Horse-Artillery ? Possessing, from their lighter construction and mounted detachments, much greater lo- comotive powers than other field batteries, FIELD GUNS AND BATTERIES. 47 they are especially adapted for following the rapid evolutions of cavalry, for sudden at- tacks upon particular points, and for sup- porting tlie advance or covering the retreat of an army. 16. How is afield gun mounted? Upon a four-wheel carriage, which answers for its transportation as well as for its service, similar to a siege carriage, but lighter, and the limber carrying an ammunition-chest. 17. Where should a battery be placed before the commencement of an action ? As much as possible under cover, b}' tak- ing advantage of banks, hollow-ways, build- ings, woods, etc. 18. 7s it advisable to move a battery at once into position in the field ? No; but if unavoidable, it should be masked as much as possible until ordered to open its lire. 19. How should a battery be mashed ? If practicable, by covering it with cavalry, in preference to infantry, as the, former does it more effectually, and is sooner moved out of the way. 20. In commencing an action, how should the fire of a battery be directed ? AVhen the enemy is in line, the fire should be directed over the whole line and not upon the real points of attack ; but when in col- umn, ready to advance, it should be concen- trated upon the real points of attack. 21. How should batteries be placed in rela- tion to the troops with which they are acting ? % HAND-BOOK OF ARTILLERY. Upon the flanks of a line, but at such a distance as not to impede its movements, and at the same time to be unfettered in their own ; the artillery may thus represent the faces of a bastion, and the line of troops the curtain. 22. Is the front of a line of troops an advan- tageous position for afield battery? On the contrary, it is the worst possible, as offering a double object to the enemy's fire, and greatly obstructing the movements of the troops; while a position in rear is nearly as bad, as the fire might seriously in- jure, or at least greatly disquiet them. 23. In supporting an attack, lohat precau- tions are necessary f The battery should be carefully kept clear of the intended line of march of our own troops, and such points occupied as may afford the greatest annoyance to the enemy. 24. Row should batteries be disposed with re- gard to the enemy's troops ? Generally so as to secure a cross-fire on his position, and on all the ground over which he moves to the attack, endeavoring to "take him at all times in the direction of his greatest dimensions: that ifi, obliquel}^ or in flank when in line, and in front when formed in columns. Moderate heights, com- manding as much as possible the surround- ing country, should always be taken ad- vantage of, but not such as may prevent operations in advance if required, 25. Is it imperatively necessary to confine FIELD GUNS AND BATTERIES. 49 positions for field batteries to the flanks of a line ? When, from particular circumstances, the front of the army is too extended, and una- voidably divided into two lines, it may become necessary to place one or more batteries in the centre, if those on the flanks are unable to sweep the whole front ; but great care must be taken not to impede the advance or retreat of the troops when required. 26. Should the fire of field batteries be car- ried on at the same uniform rate? Certainly not; the destruction of the en- emy being the object, it follows that, at distant ranges, a greater degree of care is required in pointing the guns; the fire is slow and steady, and increasing in rapidity as the enemy advances, without, however, impairing its precision. 27. Should the fire of field batteries be car- ried on in salvoes or otherwise ? Never in salvoes; but in a regular man- ner, well sustained, and with distinct in- tervals between every round, commencing slowly, and increasing in rapidity as the range diminishes. 28. Is the fire of batteries more efficacious when dispersed than when concentrated? The effects of the fire will be in propor- tion to the number of guns brought to- , gether; and, therefore, iji order to strike a decisive blow, this should at once be done. 5 50 HAND-BOOK OF ARTILLERY. 29. What projectiles arc nsed with field guns ? Solid shot, sphcrical-casc, and canister. 30. At what distance from the enemy should the several kinds of 'projectiles he employed with field battery pieces ? Solid shot from 350 yards and upward; pphcrical-case from 600 up to 1,000 yards, although it may be used within the first range ; and canister within 350 yards, or up to 4U0 against extended formations. 31. What number of rounds can be fired from a field gun in one minute f Two solid shot or spherical-case, or three of canister. 32. Why are more rounds of canister fired in a minute than of solid shot or spherical-case ? Because the latter are fired at greater distances than canister, and require the piece to be carefully aimed, thus requiring more time. 33. What is the smallest number of guns that may with safety be employed in the face of an enemy ? Never less than two, in order to secure a continuous fire and mutual support. o-t. Is the practice of employing field, batteries against those of the enemy recommended ? Only under peculiar circumstances; as, for instance, when his troops are well covered and his guns exposed, or their fire very destructive. Their fire should be directed principally against columns of attack, and masses, or FIELD GUNS AND BATTERIES. 51 upon positions which are intended to be carried. 35. Li what time could a battery come into action in the field? It could come into action and fire one round in 25 seconds, tiraing from the«order "action front" to the discharge of one piece. 36. Suppose cavalry to be advancing to at- tack infantry, and first observed at the distance of a mile, passing over the first half mile at a trot ; the next quarter of a mile at the manoiuv- ring gallop, and the remaining distance at an increased gallop^ terminating loith the charge ; occupying altogether about six minutes : during the last 1,500 yards of their advance how many rounds per pnece might a battery fire in that time f Eleven rounds with effect, thus : From 1500 to 650 yards 3' 32"— spherical-case. . .7 " 650 to 350 0' 48"— solid shot 2 *' 350 to close quarters. .0' 34" — canister 2 37. What number of rounds could a battery are against infaiitry, supposing them to pass 'over 1,500 yards in about 16i minutes? Thirty-six rounds with effect, viz : From 1500 to 650. .quick step. .9' 45" — spherical-case .19 " 650 to 350 " 3' 50"— solid shot 7 " 350 to 100 '< 2' 30"— canister 8 0' 40"— can 2 100 to close f double quick | quarter?, (and the charge. J 38. Should the enemy attempt to force the passage of a river, what is the best position for artillery to oppose it ? Wherever the best cross-fire can be ob- 52 HAND-BOOK OF ARTILLERY. tained in order to obstruct and harass him as much as possible; and if he has suc- ceeded in passing over any portion of his troops, it should be directed against their formation. Sd.^When the enemy is making the passage of a river in retreat, where should your guns be posted ? In such a position as to bear upon the batteries that cover the retreat, and also upon his bridges. 40. Til forcing the passage of a river ^ ichat is the 7nost advantageous position for artillery f The bridge being generally laid in a re- entering angle, batteries should be posted on each side of the bridge, and far enough from it to secure a cross-fire on the opposite bank. 41. Should the indiscriminate expenditure of ammunition he permitted in the field during action ? Upon no account ; ammunition should at all times be carefuU}^ husbanded, particu- larly at the commencement of an action, as the want of it at the close may decide the fate of the day ; it should also be sparingly used in skirmishes and minor affairs, espe- cially when at a distance from supplies, or in anticipation of a general action. * • 42. When should the reserve he employed? When a particular point of the line re- quires additional support, a favorable posi- tion is to be seized, an impression has been made on the line by the enemy, a forward FIELD GUNS AND BATTERIES. 53 or retrograde movement is in contempla- tion, or when a determined attack is to be made on him, then the reserve should come up and take part in the action; and it is of the utmost importance that this should be done as expeditiously as circumstances will permit. 43. Where should the reserve be placed pre- vious to an engagement ? In rear with the second line, out of the range of shot, and as little exposed as cir- cumstances will admit, but always in such a position as to have ready access to the front or rear. 44. Should guns he lightly abandoned before an enemy ? Never until the very last extremity. An artillery-man must never forget that his gun is his proper arm ; that here lies his strength -, that here is his post of honor and of duty; also, that the last discharges are always the most destructive, and may possibly insure the safety of the whole ARMY, or turn the TIDE OF VICTORY IN THEIR FAVOR. 45. What is the position for cavalry when placed in support of a battery ? On its flank, about the distance of 100 yards, and as much concealed as possible. 46. What is the proper position of field bat- teries when infantry squares are attacked by cavalry ? When infantry are formed in squares to resist the charge of cavalry, the guns should 54'"^ HAND-BOOK OF ARTILLERY. be placed onteide at the angles of the squares, the limbers, horses, etc., inside. Should the detachments be driven from their guns, the}' Tvill retire into the square, after discharging their pieces, and taking Avith them the sponges and other equipments; the moment the enemy has retired, they recommence their fire. Supposing the infantry formed in echelon of regimental squares, and that the time, or small extent of the squares would not admit of the limbers, etc., being placed inside, then the wagons and limbers should be brought up with their broadsides to the front, so as to occupy, if possible, the space between the guns, leaving no intervals for the cavalry to cut through : the prolonge or drag-ropes might also offer an effectual mo- mentar}^ impediment to theni; if properly stretched and secured. POINTING GUNS AND HOWITZERS. 55 Part II. Section I. pomTma guns and hoavitzees. 1. Wliat is meant by the term pointing a piece ? To point a piece, is to give -it such a di- rection and elevation, or depression, that the shot may strike the object; and the rule (except in case of mortars) is : First give the direction and then the elevation^ or de- pression. 2. Wlien a shot is fired from a piece, by how many forces is it acted on ? By three. — 1st. The impulsive force of the powder, which urges it forward. 2d. The resistance of the air, which tends to stop it. 3d. The force of gravity, which causes it to descend. 3. Why is it necessary to give a certain de- gree of elevation to a piece ? Because a shot describes under the action of the above forces a curve called a trajec- tory, which is situated below the prolonga- tion of the axis of the piece, the extent of its departure from this line increasing with the time of flight. Therefore, the more dis- tant the object, the greater must be the elevation to enable the shot to reach it. 56 HAND-BOOK OP ARTILLEKY. 4. Hoio is the direction given to a gun or howitzer ? By directing the line of metal upon the object. 6. How is the elevation or depression given ? The elevation or depression, which de- pends upon the charge, the distance, and the position of the object above or below the battery, must be ascertained from tables or by experiment, and the proper degree given by means of instruments. G. When xoill the object he struck by merely directing the line of metal upon it ? But in one case — when it is at point-blank distance. 7. How must the line of metal be directed for all ranges less than the point-blank range^ in order to strike it ? So as to pass below the object. 8. Give a simple rule for firing at objects within point-blank. Add to the point-blank range the differ- ence between it and the required range, set the scale to the elevation corresponding to this sum, as shown by tables of firing. Then aim the gun directly at the object ; now ap- ply the scale, and observe where the visual ray of the scale strikes the ground, and hav- ing noted this point, aim the gun directly at it. 9. How must the line of metal be directed for ranges greater than the point-blank range^ in order to strike it ? ->: Above it. ' POINTING GUNS AND HOWITZERS. 57 10. When the line of metal passes over the object, what instruments mnst he employed for giving the proper elevation ? The gunner's quadrant, or the breech- sight. 11. How is the quadrant used ? After the direction has been given, the quadrant is applied, either by its longer branch to the face of the piece, or this branch is run into the bore parallel with the axis, or it may be applied to the upper surface of the lock-piece, making the allowance due to its inclination with the axis of the piece, which ought to be previously determined, and the elevating-screw turned, or the quoin adjust- ed, until the required degree is indicated. 12. How is the breech-sight used ? It is first set to the elevation correspond- ing to the distance; it is then applied to the highest point of metal on the base-ring, and by the elevating-screw, or quoin, the notch of the breech-sight, the highest point on the swell of the muzzle, and the object, are brought in the samepine. 13. What is a line thus determined called ? An artificial line of sight. 14. In the absence of instruments, how may the elevation be given ? By placing one or more fingers of the left hand upon the base-ring, perpendicular to the axis, and using them as a breech-sight. Note. — In practice, it is well to fire two or three shots to determine the range experimentally, as it is afifected by- divers causes. 58 HAND-BOOK OF ARTILLERY. 15. Should the line of metal he always di- rected in the vertical plane passing through the object ? No; as in practice there are circumstances (as, for instance, a strong wind blowing across the field of fire) which will cause a ball to deviate from this plane, it follows that, to strike the object in such a case, the line of metal must be directed to its right or left — the gunner judging of the distance by observing the striking of the shot. 16. 7s the line of metal a permanent line under all circumstances ? No; in batteries for garrison and sea- coast defence, where the platforms are fixed, the line of metal may be considered as near- ly permanent; but with siege guns, which are mounted on travelling-carriages, the wheels of which are liable to vary in posi- tion from unevenness of ground, or unequal settling in newly-constructed platforms, this line is constantl}^ changing. It approxi- mates the higher wheel in proportion to the difference of level between the wheels ; and hence, to secure the greatest accuracy of fire, it must be frequently verified; the old marks, if not found correct, should be erased and new ones substituted. 17. When the notches or sights, which are sometimes made upon the base-ring and sivell of the 7nuzzle in field guns, for aiming the piece, are used, how is the error of direction remedied when the wheels are not in the same level ? The piece must be aimed more or less to POINTING GUNS AND HOWITZERS. 59 that side which corresponds to the higher wheel, according to the inclination. 18. When the elevation or depression has once been ascertained for any given distance, how may the firing at that distance be facili- tated ? By noting some point on the elevating- ^crew or quoin; adjusting some fixed meas- urement from a point on the stock to anoth- er point on the under side of the breech ; or by a chalk mark drawn across the face of a trunnion and its corresponding cheek. 19. When firing, either within or beyond point-blank range, may remarkable points on the ground be taken advantage of, in order to furnish an object to aim at ? Yes; some fixed object may often present itself which will serve as a point upon which to direct the line of metal. Ko means should be neglected that may tend to secure accu- racy of aim; for the shot that is thrown away by carelessness in pointing had better not be thrown at all. 20. Kow may precision of fire be secured at night ? When a fixed object is to be fired at by night, the piece should be directed during the day, and two narrow and well-dressed strips of wood laid on the inside of the wheels, and two others outside of the trail of a siege carriage, and nailed or screwed to the platform. In case of a barbette car- riage, the traverse wheels should be chocked in the proper position. To preserve the GO HAND-BOOK OF ARTILLERY. elevation, measure the height of the^ele^ vating-screw above its box, or take the measure between a point on the gun and another on the stock; cut a stick to this length, and adjust the gun on it at cach^fire. 21. Should night firing with guns be lim- ited ? Yes; it should be limited to a small num* hereof rounds, as it consumes ammunition, to little advantage. POINTING MORTARS. 61 Part II. Section II. -^jgj^ POINTING MOETAES. ^^^ 1. What is the rule for pointing mortars ? First give the elevation and then the di- rection. 2. How is the elevation given? By applying the quadrant to the face of the piece and adjusting the quoin until the required number of degrees is indicated. 8. Are the same means employed for giving mortars their direction as those which are used with guns and howitzers ? No ; because mortars are usually masked from the object to be struck by an epaul- ment or parapet. 4. To what are all the methods employed for giving the direction to mortars reduced? To determining practically two fixed points, which shall be in line with the piece and the object, and sufficiently near to be readily distinguished by the eye. These points being covered by the plummet, deter- mine a vertical pfane, which, when including the line of metal, becomes the plane of fire. 5. What is the simplest manner of directing the mortar ? By means of pointing -wires. 6. Describe this method. 6 bZ HAND-BOOK OF ARTILLERY. The two fixed points required are deter- mined b}^ planting two wires upon the epaul- ment, one upon its crest and the other about a yard in advance of it, both as nearly as possible in the vertical plane passini-; through the centre of the platform and the object. The points being thus established, the direc- tion is given to the mortar by causing a plummet, held in rear of it, to cover the wires and the line of metal. 7. /n ichat respects is this method defective f Both in accuracy of aim, and the liability of the wires being deranged by the shots of the enemy or by other causes. 8. Give a better method ? By means of pointing-stakes, by which one of the fixed points is established upon the crest of the parapet, or at the foot of the interior slope, and another in rear of the piece. Then, by a cord called the pointing- cord^ stretched between these two points, with the plummet suspended from it, a ver- tical plane is determined, with which the line of metal is made to coincide. 9. How are the stakes planted ? A stake, a foot or more in length, is driven into the crest of the epaulment, as nearly as practicable in the vertical plane of fire pass- ing through the centre of the platform, sight- ing by this stake, another long one is planted three or four feet in front of it, in line with the object. To this stake the cord is tempo- rarily attached, and stretched by the first stake, just grazing it, to a point on the POINTING MORTARS. 63 ground, one j^ard in rear of the platform. At this point a third stake is driven. The cord is removed from the second stake, which may now be taken away, and perma- nently attached to the first. 10. How is the mortar directed f The cord is stretched to the rear stake, and as near the muzzle-hand as possible, with the left hand, while the plummet is suspended against it Avith the right ; or the plummet maybe attached to the cord, just in rear of the mortar. The line of metal is then brought into the plane of these two lines. 11. How does it appear that the mortar is thus PROPERLY directed ? Because the cord, the ]ilummet, and the line of metal, are evidently in the vertical plane of fire. 12. What is done in case the shell should strike constantly to the right or left of the ob- ject ? The pointing-cord is shifted to some notch on the pointing -hoard, to the right or left, until the shell falls at the desired point. 13. Describe the pointing-board. This is a piece of wood, one foot long, two or three inches w^ide, and one inch thick, having a notch cut in the middle of one side to fit on the stake, and which is grad- uated into equal divisions from its middle. When not in use, the pointing-cord may be wound on it. 14. Describe another mode of planting the POINTING-STAKES. f 64 HAND-BOOK OF ARTILLERY. The mortar being placed upon the middle of the platform, the gunner mounts upon it, and suspends the ])lummet in front of the muzzle, covering the object. Where the plummet, thus suspended, cuts the crest of' the epaulment, the first stake is driven. A second stake is then driven in the same line between the mortar and the epaulment. The pointing-cord being attached to the first stake and stretched to the rear, over the point where the plummet touches the top of the mortar, determines the ])oint on the ground at w^hich the rear stake is driven. The first stake is then removed, and the cord attached permanently to the second stake. When the object can be seen from the mortar, owing to the interposition of some obstacle, as a parapet or a hill, two persons in sight of each other, one of whom faces the mortar and the other the object, must, by successive changes of position, place themselves in the vertical plane of fire, and at the points thus determined, stakes must be driven, one of which will serve as the object. 15. How may 'precision of fire he secured at night with mortars ? The direction is preserved by nailing or screwing two boards to the platform outside of the checks ; the elevation is marked on the quoin, or the quoin may be nailed in the proper position. f CHARGES. Ki'd Part III. CHAEGES. ♦^ 1. What is the charge of a piece of artillery? The powder with wiiich it is loaded. 2. What is the orditmry service charge of powder for heavy guns? One-fourth the w^eight of the shot. 3. What is it for firing double shot ? One-sixth the weight of one shot. 4. What is the breaching charge? One-third the weight of the shot. 5. What kind of charges are used in hot shot firing ? Small charges, from one-fourth to one-sixth the weight of the ball. 6. For what reason ? Because balls fired with small velocities split the wood in a manner which is favor- able to its burning; with a great velocity the hole closes, the ball sinks deep, and, de- prived of air, chars without setting fire to the surrounding wood. 7. To what depth should hot shot penetrate ? Not deeper than ten or twelve inches. 8. In ricochet firing, ichat kind of charges are used ? Light charges generally; varying from two-thirds to one-eighth of the ordinary charge. # HAND-BOOK OF ARTILLERY. 9. In what manner are the charges of mor- tars regulated? The c'hiirires vary with the elevcation ; or, if the elevation -be fixed at an}^ partieular angle, they must be determined by the range. 10. What are the charges for field guns arid field howitzers ? See Table, page 67. 11. What are the charges for heavy guns, columbiads and howitzers ? See Table, page 67. 12. What are the greatest charges of the sea-coast, siege and Coehorn mortars ? See Table, page 67. 13. What charge is used for projecting fire- balls from, mortars? One twenty fifth the weight of the ball. ^' CHARGES. Charges for Field Guns and Field Howitzers. FOB GUNS. FOR HOWITZERS. KIND. d ■5 . c u u i. •E ' -E. •s. 1 u 1 3 ^ ?^ ^ w For shot For sphcr. case or canis- ter For shells i ^"^^^^ charge *°'^^^*'"^'t large charge Lbs. 2.5 1.5 Lbs. 1.25 1. Lbs. 2.5 2.5 3.25 Lbs. 1.75 2. 2.50 Lbs. 0.75 1. 1. . Lbs. 0.5 0.5 0.5 Charges for Heavy Guns, Columbiads, and Howitzers. COLtJMBUDS. HOWITZERS. . I .•• •E, Lbs. 8. 1 00 Lbs^ 6. i Lbs! 4. 1 oc 1 SEA-COAST. 42-pd 32-pd 10-in. j 8-in. Lbs. j Lbs. 10.51 8. Lbs. 14. Lbs. 8. Lbs. 4. Lbs. 2. Lbs. Lbs. 12. S. Greatest Charges of Sea-coast, Siege, and Coehorn Mortars. STONE-MORTAR. •» u . 73 X 1 c 6 a 4-pdr. — §2 c^ Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. 20. 10. 4. 2. 0.5 1.5 1. HAND-BOOK OF ARTILLERY. Part IY. EANGES. 1. ^Vhat is meant by the range of a piece of artillery ? The distance from the muzzle to the first graze. ^ 2. HoxD may the range of a projectile he ex- tended ? Either by raising the piece to a higher level, or by giving its axis greater elevation within certain limits. 3. Define point-blank range. The distance from the muzzle of the piece to that point in a shot's trajectory where it cuts the prolongation of the natural line of sight a second time. 4. In what does the French definition for point-blank range differ from oiii's ? It requires that the natural line of sight should be horizontal. 5. What is the British definition for point- blank range ? The distance from the muzzle to the first graze when the axis of the piece is parallel to the plane upon which the carriage stands. 6. Explain by a figure the position of and relations existing between the line of sight, the RANGES. 69 line of fire or axis of the piece, and the trajec- tory, and also, what the point-hlank range is. - Fig. 1. A B \ \^-^^" \ ' > ABcF, the line passing through the high- est points of the base-ring and swell of tho muzzle, or the muzzle-band, is called the natural line of sight. EPcG, is the axis of the piece or li7ie of fire; the curved line PgD, described by the projectile, is called the trajectory, and is entirely below the line of lire, in consequence of the action of the force of gravity giving the projectile a down- ward tendency. The point _D is called the point-blank, and its distance from the mouth of the piece the point-blank range. 7. Mention some of the causes which vary the point-blank range. The form of the cannon; the weight or force of the charge; the diameter and weight of the projectile ; and the inclina- tion of the line of sight to the horizon. 8. Why has the form of the cannon an in- fluence on the point-blank range? Because as the difference between the diameter of the breech and muzzle becomes greater, the angle of sight, BcP=GcF (see fig.) increases, and the point-blank D is re- 70 HAND-BOOK OF ARTILLERY. moved further oft'; on the contrary, as the diameters approach to an equalit}', the point- blank approaches tlie ])iece. Within a cer- tain anirle, or when tliere is no ano-le of siglit, as is the case with some ohl liowitzers in which the line of sight is parallel to the axis of the bore, there will be no point- blank, as the trajectory will be constantly below the line of sight. 9. What influence has the charge on the point-blank range ? An increase of the charge determines a more distant point-blank; its diminution produces a contrary eftect; but beyond a charge equal to one-third the weight of the ball, the increase of range is inconsiderable, and the force of the recoil becDmes very great. 10. Hoiv does the diameter and weight of the projectile affect the range ? As the ball increases in size and density, it will overcome \\\i\\ more ease the resist- ance of the air. 11. Does the inclination of the line of sight to the horizon have much effect on the point- blank range ? Only when this inclination is very con- siderable. For the ordinary inclination, irom 0° to 15°, above or below the horizon, the difference may be wholly neglected. 12. What is the effect on the point-blank range of firing upward under a large angle? The action of the w^eight being nearly directly opposed to the imj^ulsiva force, the RANGES. 71 trajectory becomes compressed and the point- blank distance diminishes. The contrary effect obtains in firing downward under a similar angle, as the weight and the force then act in nearly the same direction. 13. Why may the point-blank be considered constant for the same calibre? The dimensions, charges, and weights of projectiles, being constant, and the inclina- tion of the natural line of sight, except in a very few cases, being comprised between 0° and 15°, it follows that for the same calibre, the point-blank may be considered constant, and may serve as a point of reference in firing at different distances. 14. What is the extreme range of a piece of artillery ? The distance from the piece to where the projectile finally rests. 15. For a given velocity, what effect has an increase of the angle of fire on the range? It increases with the angle of fire up to a certain limit, beyond which, it diminishes. 16. What angle gives the greatest range in VACUO ? Forty-five degrees. 17. When icill this angle give the maximum range in practice f Onl}' for feeble charges, and very heavy projectiles. 18. How is the angle of greatest range in practice affected by a change in the velocity and size of the projectile ? It seems to diminish as the velocity is in- % HAND-BOOK OF ARTILLERY. creased, and as the ball is reduced. For the musket the angle of maximuni range varies from 28° to 30°; and is nearly 42° for mor- tars. 19. Under what angle is a mortar usually fired ? Under the constant angle of 45°, and the charge is varied according to the range re- quired. 20. What are the advantages of this prac- tice ? Economy of ammunition ; the recoil being inconsiderable, the mortar and its bed re- ceive but little strain ; the ranges are more uniform, and the effect of a slight error in the angle of fire is less than with any other. 21. Is the mortar ever fired at any other angle than 45° ? Yes; sometimes at G0°. 22. When is the mortar fired under an angle of 60° ? When the battery is situated very near the object assailed, and it is desired that the shells may fall upon the magazines of the besieged. It is evident that projectiles the higher they are thrown up acquire more velocity in falling, besides striking the ob- ject more directly and with increased vio- lence. 28. Under what angle are stone-mortars usually fired ? Under an angle of 60°, and sometimes of 75°; that, in falling from a great height, the stones may have the maximum force of per- cussion. RANGES. 73 24. Under what angle should grenades he throivn from stone-mortars ? About 33°; otherwise they will be buried in the earth, and their fragments will not be sufficiently destructive. 25. When a gun or howitzer is aimed with the line of metal horizontal^ what is the eleva- tion equal to ? The natural angle of sight or dispart. 26. Hoio is the time of flight for siege mor- tars at an elevation of 45° determined ? It is nearly equal to the square root of -tm the range in feet divided by four. HAND-BOOK OF ARTILLERY. Ranges of Field Guns and Howitzers. KIND OF PIECE. Pow der. Ball. Eleva- tion. Range REMARKS. lbs. O / yards. 6-Pdr. Field Gan. I.2fi Shot. 318 1 2 647 867 P. B. Range. " 3 1138 « 4 5 2 1256 1523 650 1. Sph. case. Time of flight 2" " 2 30 840 do. 3" " 3 1050 do. 4" 12-Pdr. Field Gun. 2.5 Shot. 347 " 1 662 P. B. Range. " 1 30 785 '< 2 909 " 3 1269 " 4 1455 1.5 " 5 1663 Sph. case. 1 670 Time 2 seconds. " 1 45 950 " 3 " ' IT " 2 30 1250 " 4 " 12-Pdr. Field Shell. 195 Howitzer. I 1 2 3 4 5 539 640 847 975 1072 0.75 Sph. case. 2 15 485 Time 2 seconds. " 3 15 715 u 3 u '• 3 45 1050 " 4 " 24-Pdr. Field 2. Shell. 295 Howitzer. u 1 2 3 4 5 516 793 976 1272 1322 1.75 Sph. case. 2 600 Time 2 seconds. " 3 800 .. 3 .. " 5 30 1050 a 4 « 2. " 3 30 880 '• 3 « 32-Pdr. Field 2.5 Shell. 290 Howitzer. " 1 .^31 <( 2 3 4 5 779 1029 1203 1504 2.5 Sph. case. 3 800 Time 2% seconds RANGES. 75 Ranges of Field Guns and Howitzers— Qoniirm^di. KIND OF PIECE. Pow- der. Ball. Eleva- tion. Range REMARKS. lbs. o / yds. Mountain Howitzer. 0.5 Shell. 170 1 2 300 392 « 2 30 500 Time 2 sec. « 3 637 " 4 785 Time 3 sec. « 5 1005 150 0.5 Sph. case. 2 30 450 Time 2 sec. " 3 500 ■ " 4 700 Time 2% sec 4 30 4 to 5° 800 250 Time 3 sec. 0.5 Cafiister. Ranges of Heavy Artillery. KIND OF PIECE. Pow- der. Ball. Eleva- tion. Range REMARKS. lbs. / vds. 18-Pdr.Sioi>;e and Gar- 4.5 Shot. 1 641 rison Gun on Bar- u 1 30 800 Point-Blank bette Carriage. '• 2 3 950 1256 ll 4 5 14.50 1592 24-Pdr.Siege and Gar- 6. Shot. 412 rison Gun on Siege " 1 842 Carriage. " 1 30 2 3 4 5 953 1147 1417 1606 1901 Point-Blank 8. « 1 2 3 4 5 883 1170 1464 1639 1834 900 32-Pdr. Sea-coast Gun 6. Shot. 1 45 on Barbette Carriage. 8. „ 1 1 30 713 800 " 1 35 900 .1^ " 2 1100 a 3 1433 '< 4 1684 " 5 1922 10.67 ^^ 1 2 3 780 1155 1517 w HAND-BOOK OF ARTILLERY. Ranges of Heavy Artillery — Continued. KIND OF PIECE. Pow- der. Ball. Elevit- tiou. Range RSHABK8. IbB. o / yds. 42-Pdr. Sea-coast Gun 10.5 Shot. 1 775 onBarbetteCarriage. " , 1 30 2 860 1010 „ 3 4 1300 1600 ■ « 5 1955 14. (( 1 2 3 4 5 770 1128 13^0 16S7 1915 8-in. Siege Homtzer 4. 45-lb. Shell 251 Time % sec. on Siege Carriage. 1 4.35 " 2 618 u 2 « " 3 720 « 3 « " 4 992 '• 4 " " 6 1241 " 5 " " 12 30 2280 'JWdr.Iron Howitzer 2. 17-lb. Shell 295 on a Flank -Case- 1 516 mate Carriage. " 5 1322 1«4 Sph. case. 2 600 Time 2 sec. « 5 30 1050 '• 4 " 2. « 3 30 1 8S0 405 u 3 .. 84n. Sea-coast How- 4. 45-lb. Shell itzer on a Barbette 2 652 Carriage. " 3 4 875 1110 1300 « 5 6. « 1 2 572 828 u 3 4 947 1168 « 5 1463 8. " 1 646 ;: 2 3 4 5 909 1190 1532 1800 10-in. Sea-coast How- 12. 90-lb. Shell 1 680 itzer on a Barbette " 2 891 Time 3 sec. Carriage. 3 3 30 1185 1300 " 4 '• " 4 1426 "■ 614" u 5 1650 .. 6 .. RANGES. 77 Ranges of Heavy Artillery — Continued. KIND OF. PIECE. Pow- der. Ball. Eleva- tion. Kange REMARKS. lbs. o / yds. 8-in. Colunibiail on 10. 65-Ib. shot 1 932 Axis of gun 16 Barbette Carriage " 2 1116 feet above «< 3 1402 the water. li 4 1608 « • 5 1847 u 6 2010 « 8 2397 Shot ceased to a 10 28.34 ricochet on li 15 20 3583 4322 the water. a 25 27 4875 4481 16. « 27 30 4812 10. 50-lb. shell 1 919 « 2 3 4 5 6 8 1209 1409 1697 1813 1985 '^•;^03 "^ 10 15 2657 3556 «< 20 25 27 3716 4387 4171 15. " 27 30 4468 10-inch Columbiad 18. 128-lb.8ht. 394 Axis of gun 16 on Barbette Car- a 1 752 feet above riage. " 2 1002 the water. ;;' 3 4 5 1230 1570 1814 " 6 2037 Shot ceased to " 8 2519 ricochet on a 10 2777 the water. I 15 20 25 3525 4020 4304 « 30 35 4761 5433 20. " 39 15 5654 12. lOO-lb.shll 1 800 ;; 2 3 4 1012 1184 1443 (( 5 1604 18. " 448 78 HAND-BOOK OF ARTILLERY. Ranges of Ilea vy ^;7i7/e?-y— Continued. KIND OP PIECE. der. Ball. Eleva- tion. Range REMARKS. lbs. o t yds. 10-inch Columl.iiul 18. 100-lb. 8hll 1 747 on Barbotte Car- 2 1100 riage— Cbn^nu'd I 3 4 5 6 1239 1611 1805 2209 u 8 10 2489 2848 Jl ■ 15 20 25 30 3200 3885 4150 4651 " 35 4828 Time 35 sec'ds. 13-in. SearCt Mort. 20. 200-lb. shll 45 4325 T!nie40 8ec'dB. 10-in. Sea-Ct Mort. 10. 98-lb. shell 45 4250 Time 36 sec'ds. 10-iu. Siege Mortar 1. 90-lb. shell 45 300 Time 6.5 sec. 1.5 «' « 700 •' 12. " 2. " " 1000 " 14. « 2.6 «< u 1300 ^' 16. " 3. u " 1600 " 18. « 3.5 t< " 1800 " 19. " 4. " " 2100 " 21. « Ibs.oz. 8-in. Siege Mortar. 8 45-lb. shell 45 209 Time 6.75 sec. 12 " 376 - 9. " 1 « 650 " 11.5 " 1 4 " " 943 " 14. '• 1 8 » " 1318 '' 16.5 " 1 12 " « 1522 '• 18.5 " 2 " " 1837 " 20.5 " oz. 24-pound'r Coehorn 0.5 17-lb. shell 45 25 Mortar. 1. it 68 1.5 " " 104 1.75 " " 143 2. " " 165 2.75 " " 260 4. « " 422 6. " " 900 8. " " 1200 lbs. Stones. ri50 Stone-Mortar. 1.5 120 lbs. 60 \ to 1250 M 15 6-pdr. }- 50 Fuze 15 sec'ds. shells. to 150 Note. — Fire-balls, according to their size, are fired from mortars of correspoiiiling calibres. With a charge of one twenty-fifth its weight, the ball is thrown 600 to 700 yards. RICOCHET. Part Y. EICOCHET. 1. What is understood ^y ricochet firing.^ That obtained by firing a piece at very small angles of elevation, by which means the projectile which falls on ground of ordi- nary firmness at an angle not greater than 10°, or upon water at 4° or 5°, will make one or more bounds. In this case the pro- jectile is said to ricochet. 2. What is the object of ricochet firing ? To enfilade a face of the enemy's work, which is effected by causing a projectile to bound along the terreplein of the face, with the view of annoying his cannoneers, and dismounting his pieces. It is employed also in harassing an enemy, when formed or in the act of forming behind a rising ground or other obstacle, taking post in a wood, etc., and in enfilading a line of troops. 3. What are the peculiar advantages of this fire? In being able to reach objects which can- not be reached by direct fire, on account of intervening obstacles. 4. In enfilading a face of an enemy's loorh. what is the object to be fired at ? Usually some point of the interior crest 1W HAND-BOOK OF ARTILLERY. of the parapet which covers a flank of the terreplein to he reached. 5. ffliaf is the point of fall? The point of the terreplein -which is first struck by the projectile after having grazed the interior crest. 6. Tl'/iat is the angle of fall ? It is the angle made at the point of fall by the tangent to the trajectory with a horizontal line in the plane of fire. 7. How does the angle of fall compare with that of ELEVATION? It is greater. 8. Upon what do the charge and elevation depend ? Upon the distance of the object from the battery; upon the difference of level be- tween these points ; the distance of the desired point of fall from the parapet; the height of the pai-apet, etc. 9. If the embrasure be such that the object is masked, Jlow is the piece pointed ? The direction must be given, as with the mortar, by the plummet; this is held by the person who points, in such a manner as to cover both the line of metal and the object. The elevation is then given b}^ the quadrant. 10. What is the maximum angle of elevation in ricochet firing ? Against troops, it should seldom exceed 3° above the surface of the ground occupied by thcni. Against fortresses, forts, and for- tified lines, it varies from 3° to 9° above the horizontal. RICOCHET. 81 11. At what distance from the object should the ricochet battery be placed ? Never at a greater distance than 600 yards. 12. In enfilading a ivork, how should the ricochet firing be conducted? The projectile should be made to i^raze the parapet while in the descending branch of the trajectory; and this must be effected by regulating the charges and elevating or depressing the piece until the shot is seen to fall just over the interior crest of the parapet. Light charges are generally used, varying from two-thirds to one-eighth of the ordinary charge. 13. What pieces are best adapted for ricochet fire f Those which throw heavy shells ; for, if used to enfilade a work, the shells lodge and explode in the traverses, and render the guns more liable to be dismounted and their detachments put hors de combat. 14. What determines the nature of the rico- chet ? The angle of fall : it \8 flattened when this angle does not exceed 6°, and curvated w4ien it is between 10° and 12°. In the first of these fires, the velocities are great, and in the second small. 15. Tfliat are the charges for a flattened RICOCHET for siege qwns at an angle of about 3°? See Table, page 83. 16. TPhat are the charges for a flattened 82 HAND-BOOK OF ARTILLERY. RICOCHET for siege howitzers at an angle of about 3° ? See Table, page 83. 17. What are the charges for a curvated RicocHKT for a siege howitzer at an angle of a6owf 1(1° ? See Table, page 83. RICOCHET. 83 Charges for a Flattened Riochet for Siege Guns. DISTANCE. ELEVATION. CHARGE. 660 yards. 2° 45' T^^ weight of ball. 555 it. 3° T5 a 11. 440 a 3° 15' ^'o a i( 333 a 3° 35' 3'0 u u Charges for a Flattened Ricochet for Siege Howitzers. DISTANCE. ELEVATION. CHARGE. 550 yards. 440 '' 330 " 320 " 1°45' 2° 15' 2° 15' 1°45' 3 lbs. 2 lbs. 3 oz. 1 lb. 12 oz. 1 lb. 2 oz. Charges for a Curvated Ricochet for Siege Howitzers. DISTANCE. ELEVATION. CHARGE. REMARKS. 650 yards. 440 " 330 '' 220 " 7° 30' 1 lb. 4 OZ. 1 lb. 1 OZ. 14 OZ. 10 oz. The height of the object above the level of the battery being supposed to be 20 ft. 84 HAND-BOOK OF ARTILLERi'. Part VI. RECOIL. 1. What is meant by the recoil of a 'piece of artillcrii? Tlio retrooTatlc motion imprcssod upon cannon by the discharge is termed the recoil. 2. ^Yhat causes the recoil of a jyiece ? The gas produced by the ignition of the charge in the bore, expanding with equal force in every direction, finds only two waj^s of escape (the muzzle and vent) ; the pres- sure upon these points will therefore cease, while it will be proportionally increased upon the parts directly opposite, that is, the breech and the lower part of the first rein- force, producing in the first case the recoil, and in the other, indirectly, the dipping of the muzzle. 8. How far does a gun usually recoil ? This depends entirely upon the nature and inclination of the ground upon which the carriage stands, the situation of the trunnions, angle of elevation, comparative weight of the gun and carriage, and upon the strength of the charge. 4. What jnoportion does the velocity of the recoil of a piece bear to that of a ball ? Inversely as their w^eights, or masses. RECOIL. S^ 5. What proportion exists between the pres- sure acting upon the part of the bore of a piece directly opposite the verity and that which occa- sions the recoil ? As the square of the diameter of the vent is to the square of that of the shot. 6. Has the recoil any effect upon the flight of the projectile ? No appreciable effect, the shot being ex- pelled from the gun before it has recoiled a fraction of an inch. 7. What are the p?incipal inconveiiiences arising from the recoil of guns ? The necessity of running up the gun after every discharge, and consequent fatigue to the men and loss of time ; it also necessitates that a greater breadth should be given to the terreplein of a work. 8. What causes the muzzle of a piece of ar- tillery to dip ichen fired f The sudden pressure of the gas acting upon the portion of the first reinforce oppo- site to the vent, causes the piece to strike downward upon the elevating screw or quoin, and the reaction to make the muzzle *dip. 9. What influence has the position of the axis of the trunnions in respect to that of the bore upon the recoil ? If the axis of the trunnions be below that of the piece, the pressure of the breech upon the carriage will increase as the distance between the axis increases; and from this pressure there will arise a friction upon the ground which will diminish the recoil. On 1^ HAND-BOOK OF ARTILLERY. tlie. contraiy, if tlie axis of the trunnions be above that of tlie piece, the breech will have an upward tendency, the recoil will be in- creased, but the carriage, and particularly the axle-tree, will be subjected to less strain. Hence, the recoil will be transmitted direct- ly to the trunnions, if their axis (as in our service) be situated in the same plane w^ith the axis of the piece. The size of the trun- nions is made proportional to the force of the recoil. 10. Does the position of the trunnions loith reference to the centre of gravity of the piece in- fluence the recoil ? Yes; in cannon fired horizontally, or un- der very small angles, the portion in rear of the trunnions is heavier than that in front; an arrangement which increases the pres- sure of the trail on the ground so as to diminish the recoil. But in pieces fired under large angles, the trunnions are placed in rear of the centre of gravity', for the pur- pose of increasing the ease of pointing. WINDAGE. bi Part VII. WINDAGE. 1. What is meant by windage ? The difference between the diameter of the projectile and that of the bore. 2. Is it absolutely necessary to allow wind- age F Yes, in order to make an allowance for. a piece becoming foul, the expansion of shot by heat, the incrustation of rust, and for the tin straps of fixed ammunition. 3. What advantages are derived from reduc- ing the loindage ? An increase in the accuracy of fire ; a more extensive range, or an equal range with a smaller charge, as there is less loss of gas; and less injury to the surface of the bore. 4. Why should the bore suffer less injury by a diminution of the icindage ? Because in proportion to the decrease of windage there will be less space for the re- flections of the shot along the bore, and consequently lelss injurious power exercised upon it. 5. What is the loss of velocity by a given loindage proportional to ? It is directly as the windage, and inverse- ly as the diameter of the bore very nearly. 8§ HAND-BOOK OF ARTILLERY. 6. What is the loss of velocity by the wind- age of the hall ? 1 Initial velocity of ball. Loss of velocity IV . KIND OF GUN. Without windage With windatre of l-40th diam. windage of l-40tli diam. lbs. 4 feet. 1444 feet. 1271 feet. 173 pr. cent. 12 2-t-pdr. Siege \ 4 6 1600 1890 14.33 1723 167 167 10 9 12-pdr. 25 calibres....-^ 2 3 4 1617 1915 2124 1528 1793 1992 1444 1742 1951 173 173 173 11 9 8 12-pdr. Field, 16 cali- f bres j 2 1370 1635 1834 158 158 158 10 9 8 6-pdr. Field 1.5 1734 1560 174 10 7. Wliat windage is allowed to guns ? IRON. BRASS. Sea-coast. Siege and Garrison." Field. 42 32 24 18 12 12 inches. 0.10 6 inches. 0.16 inches. 0.15 inches. 0.14 inches. O.IX inches. 0.10 inches. .0.9 WINDAGE. 89 8. What windage is alloioed to coliwibiads and howitzers 9 COLUMBIADS. Howitzers. Sea-Co.ist. Siege and Garrison. Field. Moun- tain. . u J TS rs CO o e 00 1 in. in. in. in. in. in. in. in. in. 0.12 0.12. 0.12 0.13 0.13 0.14 0.15 0.14 0.10 in. 0.10 9. What amount of windage is allowed to mortars ? IRON. BRASS. IRON. Heavj'. Light. Stone Mortar. Coehorn 24rpdr. Eprou- vette. inches, inches. 13 13 inches. 0.13 inches. 0.12 inches. inches. 0.14 inches. 0.025 hand-book of artillery. Part VIIL GUNPOWDER. 1. What are the ingredients in gunpowder ? Saltpetre, charcoal, and sulphur. 2. What are the 'proportions ? In the United States, 75 to 76 saltpetre, 14 to 15 charcoal, and 10 sulj^hur. Ensjland, 75 saltpetre, 15 charcoal, 10 sulphur. France, 75 " 12i " 12^ " Prussia, 75 " \^ " lU " 3. What is the combustible ingredient? Charcoal. 4. What is the use of the saltpetre? It furnishes the ox^'gen necessary to sup- port a rapid combustion, and to change the whole mass into gas. 5. What is the use of sulphur ? It adds consistency to the mixture and intensity to the flame, besides rendering the powder less liable to absorb moisture. 6. On ivhat does the quality of gunpowder depend ? On the intimate mixture and proper pro- portions and purity of the ingredients. 7. In what does the manufacture of gunpow- der consist ? In pulverizing the ingredients, incorpora- tion, compression, granulation, drying, glaz- ing, and dusting. GUNPOWDER. 91 8. Explain the method of making gunpowder hy the pounding mill. The charcoal in small pieces is first placed in the mortars, with a quantity of water, and pounded for half an hour; after which, the saltpetre and then the sulphur, previous- ly pulverized and sifted, are put in, and the whole well mixed with the hand ] it is then pounded in the mortars, and at the end of each hour, the composition is passed from each mortar into the next. At the sixth or eighth change, add half a pint of water; it is then pounded two hours without clianging the mortars, in order that it may form into cake. It is then partially dried, and grained in a graining sieve, or passed between wood- en rollers. The grains are then sifted to separate those which are too coarse and too fine, and also to separate from each other the different kinds of grains for cannon^ mus- ket, and rijie powder. It is then glazed in large glazing barrels, which make 15 or 20 revolutions in a minute. A charge of 500 lbs., is thus treated for about twenty-four hours. It is then dried either in the open air, or in a drying house. If in the open air, when the sun is too hot, the powder should be covered to prevent the loss of sulphur. It is then dusted^ by being sifted in fine sieves, or through bolting cloths. 9. What other machines besides the pound- ing mill are used in pulverizing and incorpo- rating the ingredients of gunpowder ? Eolling barrels, and the cylinder or rolling mill. 92 HAND-BOOK OP ARTILLERY. 10. IVhat advantage is gained by the use of the ROTA AS () BARRELS y It lessens the duration and danger of pounding in the mortars. After the ingre- dients are pulverized and mixed in the roll- ing barrels, the mixture is placed under the pestles of the pounding mill, 10 per cent, of water is added, and it is beaten for three hours onl3^ 11. Which mill is noiv generally used ? The CYLINDER MILL, whicli performs at the same time the operations of pulverizing, incorporating, and pressing the composition. It consists of two cylinders, of marble or cast-iron, weighing about jive tons each, rolling in a circular trough of the same material, the inner diameter of which is about three feet; a wooden plough follow the cylinders, to bring the powder toward the centre of the trough. The cylinders re- volve ten times in a minute, and run from one to three hours on each charge of 50 lbs.* of composition. 12. hoes powder inflame instantaneously ? ]S"o ] its inflammation is gradual and pro- gressive, and in a gun the projectile com- mences to move before the whole charge is ignited. 13. Why should gunpoivder be grained ? In order to facilitate the transmission of the flame. When the powder is very fine, and in large and compact charges, the flame cannot penetrate it, and it burns slowly and in successive layers. GUNPOWDER. 93 14. Which burns quickest, the small or large grained powder P Before coming to the limit of dust, the smaller the grain the more rapid the com- bustion, and the greater the bursting force of the powder. 15. What is the difference between the igni- tion and combustion of large and small grained poivder ? With the large grained, the ignition is more rapid, but the combustion slower; with small grains, the contrary is the case. 16. Why should the grains be angular ? Because they present a greater surface to the action of the flame, and therefore burn quicker. 17. Why should powder be free from dust f Because the dust fills up the intervals be- tween the grains, and forming a compact mass, retards combustioii. 18. To what special purpose are large and small grained powders applied? The large for cannon, and the small for small arms. 19. Ho\D is the size of the grain for each kind of powder tested ? By means of sieves or gauges. 20. How many grains of powder are in 10 grains Troy weight? Cannon, 150 ; Musket, 2,000 to 2,500 ; and Jtifle, 12,000 to 15,000. 21. What is the object in glazing powder ? Glazed j^owder does not absorb moisture, or break uj) in transportation, so much as unglazed. ^ 94 HAND-BOOK OF ARTILLERY. 22. frhat is the established mode of proving the strength of powder in the U. S. ? A sample is taken from each barrel, and the strength determined by the eprouvette mortar. 28. V^liat is the least range alloiced ? The general 7«ert7i range of new powder must not he less than 250 yards; but no powder ranging below 225 yards is received: 24. When is poivder in magazines considered unserviceable? When it does not range over 180 yards. 25. What is the range of good powder ? Cannon from 280 to 300 yards. vSmall grained from 800 to 320 yards. 26. What other means is there for determin- ing the strength of powder ? The GrUN AND Ballistic Pendulum, and Navez' Electro-ballistic Machine. The latter is considered the best for determining the initial velocity. 2 7 . What is the hygrometric proof of powder? Samples are placed in shallow tin pans, set in a tub, the bottom of which is covered with water; the j^ans should be about an inch above the water, and the tub covered. Good powder will not absorb more than 2^ per cent, in 24 hours. 28. How can the relative quickness of two hinds of powder he determined ? By burning a train laid in a circular or other groove, which returns into itself, made in a piece of hard wood ; one-half of the groove being filled with each kind of pow- GUNPOWDER. 95 der, and fire communicated at the junction of the two trains, the relative quickness is readily deduced from observation of the l^oint at which the flames meet. 29. What are the qualities of good powder P It should be perfectly free from dust, uni- form in strength and size of grains, angular and irregular in formj in color, brownish black, or slate color j so hard fts not to be easily crushed by pressure with the finger; and should leave no beads or foulness when flashed in quantities of 10 grs. on. a copper plate. 30. What is the expansive velocity, and pressure of ignited powder ? The expansive velocity is about 5,000 feet per second, and j^ressure about 2,000 atmos- pheres. 31. What is the weight of a cubic inch of powder ? About half an ounce; a cubic foot will therefore weigh about 54 pounds, and 32 cubic inches one pound. 32. How is government poioder packed? In barrels of 100 lbs. each; the barrels being large enough to allow sufficient space for the powder to move when rolled to pre- vent its caking. 33. How are the barrels marked ? On one head with the place and year of manufacture, and with the kind of grain : cannon, musket, or rifle ; on the other head wdth the year in which it was proved and the proof-range, leaving room for subsequent jm HAND-BOOK OF ARTILLERY. proofs, which are marked in the same man- ner. o4. When jwwder is injured by dampness, can if he restored? If tlic water absorbed docs not exceed 7 per cent., it can be by drying. If it has ab- sorbed from 7 to 12 per cent., after drying it remains porous and friable, and is unfit for transportation. In this case it is better to work it ove^. 35. How is powder stored ? In magazines especially constructed for the purpose. The barrels are generally j^laced near the sides, three tiers high, or four tiers if necessary; small skids should be placed on the floor and between the sev- eral tiers of barrels, in order to steady them, and chocks should be placed at inter- vals on the lower skid, to prevent the roll- ing of the barrels. 30. Kow are the different kinds of powder arranged ? Those barrels of the same kind, place and date of fabrication, and proof-range, are piled together. 37. Should it be necessary to pile the barrels more than four tiers high, what is done? The upper tiers are supported by a frame resting on the floor, or the barrels may be placed on their heads, with boards between the tiers. 38. What is necessary for the preservation of the powder ? The magazine should be opened and aired GUxNPOWDER. 97 in clear, dry Aveather, and the ventilators should be kept free. 39.. How may the moisture of a magazine he absorbed ? By chloride of calcium suspended in a box under the arch, and renewed from time to time. 40. When the magazine is open, what pre- cautions should be observed? The sentinel or guard should have no fire- arms, and any one who enters it should take off his shoes, or put socks over them. ISTo sword or cane, or anything which might oc- casion sparks, should be carried in. 41. How should poicder in barrels be trans- ported ? The barrels should never be rolled ; they should be carried in hand-barrows, or slings made of rope or leather. In wagons, the ^barrels should be packed in straw, and not allowed to rub against each other, and the whole covered with thick canvas. 42. What precaution should be used to pre- vent powder caking ? The barrels should be taken outside the magazine and rolled on boards. 4o. Where should cartridge-bags be filled ? In the filling-room of the laboratory, or a small magazine, and not in the general magazine. 9 HAND-BOOK OF ARTILLERY. Part IX. PKOJECTILES. 1. What jirojectiles are made use of in the service ? Solid shot, shells, spherical-case or shrap- nel, canister, grape, grenades, stones, car- casses, light and fire-balls. 2. What is a solid shot? A solid sphere of cast-iron, almost exclu- sively appropriated to guns. The gun de- rives its denomination from the weight of the shot, as 6-pdr., 12-pdr., etc. 3. What is a shell, and its use? A hollow sphere of cast-iron, containing powder, which is ignited b}^ means of a fuze; when fired at troops, it should be prepared to burst over their heads, or, if the ground be favorable, to ricochet a little in front and plunge into the column. When fired at works or buildings, it should explode after penetration. 4. What is a spherical-case, and what ad- vantages does it possess ? It is a shell much thinner than the ordi- nary shell, and filled with leaden bullets and a charge of powder sufficient to burst it, which is done by means of a fuze, as with a common shell, at any required distance. It PROJECTILES. 99 is thus calculated to extend all the advan- tages of canister shot to distances far beyond the reach of that projectile. It is fired both from sjuns and howitzers. 6. What are canister shot ? Cylindrical tin cases with iron heads, of calibre suitable for different pieces of ord- nance, filled with cast-iron balls, arranged in tiers, and packed in with dry saw-dust; they ar<3 fired at ranges not exceeding 400 yards, but their most destructive effects are from 100 to 200 yards. 6. What are grape shot ? A certain number of iron balls, usually nine, put together by means of two cast-iron plates, two rings and one pin and nut. Each plate has on the inside three beds for the shot, of a. depth equal to half the thickness of the plate, and of the form of a spherical segment, the curvature of which is the same as that of the shot. An iron pin, riveted to the bottom iron plate, passes through the centre and also through the top plate, where the whole is secured by a nut and screw. Note. — The use of these shot for field pieces has been discontinued, canister answering the purpose of these shot. 7. How ivere the balls fixed in the old pat- tern ? They were placed in tiers around an iron pin attached to an iron tompion at the bot- tom, and put into a canvas bag, and then quilted around with a strong cord. 8. What is a grenade ? A shell, thrown from the hand, or in has- 100 HANP-BOOK OF ARTILLERY. kets from tlic stonc-mortar, .and ignited as other shells by moans of a fuze. 9. How many kinds of grenades are made use of? Hand grenades and rampart grenades. Six- pounder spherical-case may be used for the former, and shells of any calibre for the lat- ter. 10. To what purposes are grenades applied ? lihay are useful in the defence of works, the smaller thrown by hand-into the head of a sap, trenches, covered-way, or upon the besiegers mounting a breach ; the larger kinds are rolled over the parapet in a trough. 11. What is a careass, and its use? It is a spherical shell having three addi- tional holes of the same dimensions as the fuze hole, pierced at equal distances apart in the upper hemisphere of the shell, and filled with a composition which burns with intense power from eight to ten minutes, an d^ the flame issuing from the holes sets fire to everything combustible within its reach ; it is used in bombardments, setting fire to shipping, etc.; and is projected from cannon like a common shell. 12. What is a substitute for a carcass ? Common shells loaded in the following manner : The bursting charge is placed in the bottom of the shell in a flannel bag, over which carcass composition is driven until the shell is nearly filled ) then insert four or five strands of quick-match, which must be secured by driving more composition upon PROJECTILES. 101 it. These shells, after burning as a carcass, explode. 13. What is afire-ball, and its use ? It is a projectile of an oval shape, formed of sacks of canvas filled with combustible composition which emits a bright flame. Its use is to light up the enemy's works, and it is loaded with a shell to prevent it from being approached. 14" What is a light-hall ? Light-balls are the same as fire-balls, ex- cept that there is no shell in them, as they are used for lighting up our own works. 15. What is a smoke-ball ? A hollow paper sphere, similar to a light ball, and filled with a ct)mposition which admits a dense, nauseous smoke ; it is em- ployed to suflbcate the enemy's miners when at work, or to conceal one's own operations; it burns from twenty -five to thirty minutes. 16. In field jneces, to what is the projectile attached ^ To a block of wood called a sabot. 17. Are the projectile and cartridge ever at- tached to the same sabot? Yes; in field guns, and the IS-pdr. field howitzer; the whole then constitutes a round of fixed ammunition. 18. What is the arrangement in case of the 33 and ^^-pdr. field howitzers? ■ The projectile is separate from the charge, and the cartridge is attached to a block of wood called the cartridge-block^ the object of which is to give a finish to the cartridge and fill the chamber. 102 HAND-BOOK OF ARTILLERY. 19. What difference is there in sabots for field service? Sabots for shot and spherical-case or guns have one groove for attaching the cartridge — those for gun canisters and for the l:2-])dr. howitzer sliells, spherical-case and canisters have two grooves. Those for the 33 and S4-pdr. howitzers have no grooves, but are furnislicd with handles made of cord, pass- ing through two holes in the sabot, and fas- tened by knots on the inside. 20. Mow are projectiles for field service fas- tened to the sabot ? By straps of sheet tin, or of strong canvas when tin or sheet iron cannot be procured. 21. How many strajys are employed, and how are they fastened ? For shot, there are two straps crossing at right angles, one passing through a slit in the middle of the other. For shells, there are four straps soldered to a ring of tin, or fastened to it by cutting four slits in the ring, into which the upper ends of the strap are hooked, and turned down on the inside of the ring. The sabots for 3S and S4-pdr. field howitzers having no groove, each strap is fastened b}^ one nail on the side, and two under the bottom of the sabot. 22. What is a canister for field ser- vice ? It consists of a tin cylinder attached to a sabot, and filled with cast-iron shot. 23. How is it made? The cylinder is fastened to the sabot by PROJECTILES. 1(33 six or eight nails, and a plate of rolled iron is placed at the bottom on the sabot. It is closed with a sheet-iron cover after being filled, the top of the cylinder being cut into strips half an inch long, and turned down over the cover. 24. hi case of heavy guns are the shot at- tached to the sabot ? They are generally without a sabot. 25. JELow is it with shells ? The}' are strapped to sabots made of thick plank, with strips of tin, as in case of strap- ping shot for field service. 2(5. How is it with canister for siege and sea- coast guns? They have no sabot; the tin is turned over tlie iron bottom. 27. How is it with canisters for the S-inch siege and sea-coast howitzers? They are attached to sabots in the same way as the field howitzer canisters. The sabot for the siege howitzer has a hemi- spherical bottom, and the sea-coast a conical one, to suit the connecting surface between the cylinder of the bore and the chamber in these pieces. 28. Are sabots used icith grape shot ? Yes, in the 8-inch sea-coast howitzer. 20. What is its form, and how fastened? It is conical; and ma}' be fixstened to the lower plate with screws, or the pin may be made long enough to pass through it; or else the sabot may be inserted into the piece separately from the stand of grape. W4 HAND-BOOK OF ARTILLERY. 30. What is the object of fixing shot or shells to loooden bottoms? To prevent injniy to brass cannon; and to insure the fuze of a shell being retained in the axis of the piece. 31. What jiroportion docs the weight of one shot bear to that of another? The proportion is, as the cubes of their diameters. 82. How is the weight of a cast-iron shot or shell determined. ? Multipl}^ the cube of the diameter of the shot in inches, or the difference of the cubes of the exterior and interior diameters of the shell by 0.134 for the weight in pounds. In case of lead balls, the multiplier is 0.214. The cube of the radius in inches of a cast-iron shot will be very nearly equal to its weight in pounds. 38. Hoio is the diameter of a cast-iron shot of a given loeight found ? Divide the weight in pounds by 0.134, and extract the cube root of the quotient, which will be the diameter in inches. 34. How is the quantity of powder which a shell ivill contain found ? Multipl}^ the cube of the interior diameter of the shell in inches, by 0.01744 for the weight of powder in pounds. iNoTE. — These multipliers are found as follows: Suppose W to represent the weight of a body, D its density, V its volume, and (j the weight of the unit of mass, then 11^=: /> V 1=0.036201 d'^cI^ (supposing d to be the di- PROJECTILES. 105 ameter and the body to be spherical)=:0. 036201 X 0.5236 /;cZ3z=0. 18955 Z)rf3. If vre now substitute for D the spe- cific gravity of cast-iron shot or shells=7.000, we have W =7 X 0.0189y5c/3 = 0.134rf3; and if for D we substitute the specific gravity of lead, W^= form of the socket and handle of the fork. 56. Where are the handspikes applied in traversing the carriage ? To the pivot-bolts of the traverse-wheels, which projecj to the rear; or under the traverse-wheels. 57. Why does the chassis slope toward the front ? CARRIAGES AND MACHINES. 149 In order to diminish the recoil, and aid in running the piece into battery. 58. Describe the columbiad gun-carriage? It is a triangular framework, consisting on each side of an upright, a horizontal rail or tie, and a brace, firmly mortised j^nd bolted together, forming the cheeks, which are joined by a transom at each end. These project below the lower surfaces of the ties, and fit in between the rails of the chassis, serving, like the flanges on the rollers in ' the other barbette carriages, to prevent the gun-carriage from slipping sideways off the chassis. ^ Through the front transom, and near the front ends of the ties, an iron axle-tree is passed, working in iron boxes fitting in the ties. On the projecting ends of this axle- tree the rollers or manoeuvring-wheels are fixed (the axis of which are eccentric with the axis of the axle-tree), the extreme ends of the axle being octagonal in shape, to fit the wrench of the iron handspike. These eccentrics are so ari-anged that when the centres of the wheels are at their lowest points, the surfaces of the wheels bear on the rails of the chassis and raise the gun- carriage tie from it; and when the^centres are at the highest points, the surfaces of the wheels do not touch the rails, and the ties are in contact with them.* A similar ar- . * A couple of notches or indentations are made on the ^nds of the eccentric axles. When these notches are in a vertical line, the wheels rest on the rails ; byit when they are in a horizontal or inclined line, the ties rest on them. 150 HAND-BOOK OF ARTILLERY. rangement is made for the rear part of the carriage, except that the axle does not ex- tend all the way through, but the wheel on each 8idc has a projecting piece of axle which works into a box placed near the end of the tie. The wheel is thrown into or out of gear, that is, made to bear on the rail of the chas- sis, or relieved from it, by turning the axle with a wrench placed on the octagonal end. In the direction of the radii of the wheels, but inclined outward, mortises are placed for the reception of the end of the iron handspikes, by acting on which, while in- serted, the w^heels are turned, and the car- riage moved back and forth on the chassis. Ordinarily, when the wheels are thrown into gear, the carriage being back, it will run into battery of itself The elevating ari^ngement consists of an elevating-screw, working into a screw-bed, which slides in a vertical box, and carries on the top of it a movable pawl to fit into the notches cut in the breech of the gun, in order to give considerable elevations. For the purjDOse of transferring the pawl from one notch to the next, it has a slit in it, through w^hich the elevating-bar is passed, and the gun supported by making use of the edge of the elevating-box as a fulcrum. This arrangement is over the rear transom. 59. Describe the chassis of the coliimbiad carnage. - It consists, like those used wath other bar- CARRIAGES AND MACHINES. 151 bette carriages, of two rails connected by •three transoms; but the tops of the rails are shod with iron plates, and the rear hurt- ers are the large heads of heavy bolts which pass entirely through the rails. The front hurters are fixed to the front transom by a heavy plate and bolt. . Traverse-wheels are placed under both fcont and rear transoms, and the chassis moves on a pintle passing through the mid- dle transom. Two of these wheels are placed under each end of the chassis, their axes being kept in place by straps bolted to the transoms. Eecesses are cut in the under side of the transom for the wheels to turn in. This chassis has no tongue. 60. Of how many parts are casemate car- riages composed ? Like barbette carriages, of a gun-carriage and chassis. 61. Describe the gun-carriage. It consists of two cheeks, joined together by as many transoms, and su])ported in front by an axle-tree on truck wheels, and in rear on the rear transom, which is notched to fit the tongue of the chassis. Each cheek is formed of two pieces, one on top of the other, and connected by dowels and bolts. On the under side, near the front, a notch is cut for the reception of the axle4ree, which is of oak; and nearly over the axle, on the upper side of the cheek, the trunnion-bed is placed. The rear of the upper piece of the cheek is cut into steps, which give a better j^ HAND-BOOK OF ARTILLERY. hold for the assembling-bolts than a uniform slope, and o;ive purchases for the handspikes in elevating the piece. On the inside of each clieek, just in rear of tiie axle, a verti- cal guide is tixed to keep the carriage on the chassis. It is of wood, and bolted to the front transom and axle-tree. The top of the front transom is hollowed out, to admit the depression of the piece. Behind the rear transom and at the notch cut in it, there is an eccentric roller, so arranged as to bear the weight of the rear part of the carriage, or not, according as it is thrown in or out of gear. Jni ear the rear end of each cheek, and out- side, a heavy trail-handle of iron is placed, and used in manoeuvring the jDiece. On the ends of the axle truck wheels are placed, with mortises sloping outward in the direc- tion of the radii, for the insertion of the handspiivcs in running from batter}". The elevating apparatus consists of a cast- iron bed-plate, secured to the rear transom ; an elevating-screw and brass nut; tiie nut being acted on by an oblique-toothed wheel, turned by a handle placed outside the right cheek. 62. Describe the chassis. It consists of two rails and a tongue, joined by two transoms, and supported on traverse-wheels in front and rear. The track on each rail is curved up at each end, and provided with hurters to prevent the car- riage from running off the chassis. A prop, CARRIAGES AND MACHINES. 153 fastened under the rear end of the tongue, prevents the chassis from upsetting back- ward in firing heavy charges, and may be used as a point of support in raising the chassis. An iron fork is bolted to the under- side of the front end of the tongue, to which is bolted an iron tongue. An opening in the masonr}^ below the embrasure is left for this tongue, and it is •secured in its place by dropping the pintle from the embrasure down through the eye of the tongue. 63. Where is the flank-casemate carnage employed ? It is especiall}^ adapted to the mounting of the 24-pdr. iron howitzer in the flanks of casemate batteries, for defending the ditch j and both the gun-carriage and chassis are narrower and lighter than the other case- mate carriages. 64. Describe the gun-carriage. The cheeks are made of white oak, and connected by two iron transoms, the front one projecting below the cheeks, and resting on the chassis with a projection on the bot- tom of it, fitting in between the rails. The bottom of the trail has the same slope as the upper surface of the chassis on which it rests ; so that when its eccentric roller is out of gear, the rear parts of the cheek fit the rails. The remaining |)ortion of the bottom of the cheek makes an angle with the rail, and has in front a fork, and a roller which runs on the rail of the chassis when the eccentric is in gear. Each cheek has oil the 154 HAND-BOOK OF ARTILLERY. side a trail-handle and a man(envrinfi;-ring. In rear of the rear transom is placed an eccen- tric roller, havin<^ a ]n'ojection in the middle of it just larii:e enoii«i;li to tit in l)et\veen the rails of the chassis, and guide the trail of the curriage. When this roller is in gear, the weight of the trail rests upon it, while that of the front part of the carriage is thrown upon the front rellers, and the piece is then easily run in and out of hattery; but the roller being out of gear, as when the piece is about to be fired, the weight rests upon the rear part of the cheeks and the front transom, and friction is brought into play to diminish the recoil. Cap-squares are used with this carriage. 65. Describe the chassis. It consists simply of two rails 8 in. apart, and joined by four transoms and assembling- bolts. Hurters on the rear ends of the rails only are used, as the bottom projection of the front transom prevents the carriage run- ning too far into battery. The front end of the chassis rests on the sole of the embra- sure. The end is provided with a pintle- plate, and a strap of half-inch iron through which the pintle passes to the masonry be- neath. The rear of the chassis is supported by an iron prop, the lower end of which is attached to two traverse-wheels. 66. What kind of carriages have been rec- ommended for use in garrisons, instead of wooden ones? Wi'ought-iron carriages, all made in a sim- CARRIAGES AND MACHINES. 155 ilar manner, differing only in weight and dimensions. 67. What is the objection to cast-iron ? Its weight, and its great liability to splin- ter when struck by shot. 68. Of how many parts is the wr ought-iron carriage composed ? Like the wooden ones of a gun-carriage ^nd chassis. \ 69. Describe the gun-carriage. It consists of two cheek-plates of thick sheet-iron, each one of which is stiftened by three trough-beams, termed braces, bolted on the inside of the cheeks. Along the bot- tom of each cheek an iron shoe is fastened by pieces of angle iron, bolted to the cheeks and the shoe. This shoe is bent upward at i)oth ends, in front being bolted to the flange of the front brace, and in rear to the flange of the rear brace. The rear bent portion is longer, and terminated at top by another bend at right angles, which serves as a point of application for a lever. The trunnion-plates rest on the top ends of the braces, being secured to them through .their flanges by movable bolts and nuts. The cheek-plates are assembled together by transoms made of bar-iron bent at both ends, and bolted to the cheek-plates through the braces. The cheek-plates are parallel to each other. The carriage is supported in front on an axle-tree with truck wheels, in a similar manner to the wooden casemate carriao-e. PP hand-book of artillery. . 70. Describe the chassis f It consists of two. rails of wroug-lit-iron, the cross section of each being in the form of an I. The rails are parallel to each other, and connected by iron transoms and braces. In the S and 10-in. columbiad and bar- bette carriages, the middle transom is of wood strengthened by iron plates and bolts. The chassis is supported on traverse- wheels. A prop is placed under the rails to prevent sagging. 7i. What carriage is used for conveying ammunition for a field battery? The CAISSON. 72. Describe it. A four-Avheeled carriage, consisting of two parts, one of which is a limber similar to that of the gun-carriage, and connected in a flimilar way by a wooden stock and lunette. On the axle-body of the rear part, and parallel to the stock, are placed three rails upon which are fastened two ammunition- boxes, one behind the other, and similar to the one on the limber; so that the caisson has three ammunition-boxes which Avill seat nine cannoneers. The interior compart- ments of the ammunition-boxes vary ac- cording to the nature of the ammunition with which they are loaded. In rear of the last box is placed a spare wheel axle of iron, with a cliain and toggle at the end of it. On the rear end of the middle rail is placed CARRIAGES AND MACHINES. 157 a carriage-hook, similar to a pintle-hook, to which the lunette of a gun-carriage whose limber has become disabled may be attached, and the gun carried off the field. The caisson has the same turning capacity and mobility as the gun-carriage, so that it can follow the piece in all its manoeuvres, if necessary. It also carries a spare wheel, spare pole, etc. 73. What provision is made fa?' repairing the carriages of a field battery when required ? Every field battery is provided with a FORGE. 74. Describe this wagon. It consists, besides the limber, of a frame- work on which is fixed the bellows, fire- place, etc. Behind the bellows is placed a coal-box, which has to be removed before the bellows can be put in position. In the limber -box are placed the smiths' tools, horse-shoes, nails, and spare parts (iron) of carriages, harness, etc. 75. Describe the battery-avagon. It consists, besides the limber, of a long- bodied cart with a round top, which is con- nected with the limber in the same way as all other field carriages. The lid opens on hinges placed at the side ; and in rear is fixed a movable forage -rack for carrying long forage. One of these wagons accom- panies each field battery, for the purpose of transporting carriage makers' and saddlers' tools, spare parts of carriages, harness and 14 158 HAND-BOOK OF ^VRTILLERY. equipments and rough materials for replac- ing diftVi-ent parts. Both this and the forge are made of equal mohility with the otlier field earriages, in order to aceompany them wherever they may be required to go. 70. lioic many kinds of loheels are employed for field carriages ? Two : No. 1 for the 6-pdr. gnn-carriage, the caisson, the forge, the batter^'-wagon, and for the limbers of all field carriages; No. 2 for the 24:-pdr. howitzer and the IS-pdr. gun-carriages. 77. Jn what respects are these ivheels similar? They are of the same form and height, and they fit on the same axle-tree arm. The height is 57 inches, and each wheel is com- posed of 14 spokes and 7 fellies. 7^. JECoiv do they differ ? In the dimensions of their parts, and in strength and weight. 79. What is the weight of these wheels f No. 1, 180 lbs; No. 2, 196 lbs. 80. What is the weight and height of a wheel of siege gun-carriages and limbers ? Weight 404 lbs., and height 60 inches. 81. What is the portable forge designed for? Service in a mountainous country, where wheeled vehicles cannot travel, for the pur- pose of making repairs, not only for the ar- tillery, but for all other arms of service taken on such expeditions. 82. What is the mortar-wagon designed for? CARRIAGES AND MACHINES. 159 The transportation of siege mortars and their beds, or of guns or large shot and shells. 83. Describe this lo'agon. The limber and wheels are the same as those of the siege gun-carriage. The body consists of a platform of rails and transoms, resting on an axle-tree, the two middle rails being prolonged to form the stock; six stakes or standards are inserted in sockets on the side of this platform, and used to se- cure the load. The side rails are prolonged to the rear, and furnish pivots for a roller placed imme- diately in rear of the platform. This roller has holes for the insertion of handspikes, and is used in loading the wagon ; the guns, mortars, etc., being drawn up on the stock. A muzzle-bolster on the stock near the limber, and a breech-hurter near the hind part of the wagon, are provided and used when long pieces are transported on it. Mortars are usually carried mounted on their beds. 84. What is the use of the handcart ? For the transportation of light stores in siege and garrison service. 85. Describe it. It consists of a light body with shafts, mounted on two wheels. The shafts are joined together at the ends, and supported immediately in front of the body by iron legs. 86. What is the use of the hand sling-cart ? It is used in siege and garrison service for transporting artillery short distances. 163 HAND-BOOK OF ARTILLERY. , 87. Describe it. ' ■^^^■ It is a two-wheeled earriac^e, made entirely of iron, cxee])t the pol(?, which is of oak. The axle-tree is arched to make it stroiiij^er, and connected with the pole by strong wrought- iron strn]is and braces. In the rear of the axle a projection is welded to receive the end of a strong hook. The end of the pole terminates in a ferule and an eye. The eye is for the purpose of attaching to tlie cart, when necessary, a limber or a horse. 88. HoiD great loeights can he transported by this cart ? It should not be used with heavier weights than about 4,000 lbs., but in case of necessity a 24 or 32-pdr. gun may be transported on it. For heavier guns or material, the large sling-cart, drawn by horses or oxen, should be used. 89. What is the field and siege gin and its use ? It Consists, like all gins, of two legs and a pry -pole, a windlass, sheaves, ])ulleys, and a fall or rope, and is used for mounting or handling guns, or other heavy bodies, in the field or in the trenches of a siege. The legs are about 142 feet long, and the height of the gin about 12 feet. 90. How does the garrison gin differ from the field and siege gin f It is heavier and stronger, as it is used for mounting heavier guns, and has not to be transported like the other with an army in CARRIAGES AND MACHINES. 161 the field. The legs are longer and the gin higher than the other. 91. Describe the casemate gin. It does not differ from the garrison gin except in its height (which is about that of the field and siege gin) and the thickness and strength of the parts. 162 HAND-BOOK OF ARTILLERY. Part XIII. PRACTICAL GUNNERY. 1. How may the initial velocity of a shot or shell be ascertained ? Approximately by the empirical formula. Where F=initial velocity. rt=a coeflScient, whose value de- pends on the windage. (?=charij;e ) . ^ . V , n 1 11 \\\\ lbs. ?(;=weight of ball j The values of <2 are : Windage. Values of «. 0.175 .... 3.6 0.125 . . . . 4.4 0.090 .... 5.0 2. Does a shot or shell continue at the same uniform velocity during its flight? The velocity decreases as the distance in- creases, in a proportion a little higher than the squares of the velocities throughout. 3. What causes a decrease in the velocity of a shot ? The resistance of the air, which varies as the square of the velocity of the shot. 4. With balls of different diameters, and PRACTICAL GUNNERY. 163 equal velocities, to what is the resistance of the air proportional ? Their surfaces, or the squares of their diameters. 5. Would the velocity of the shot be increased by lengthening the gun ? Only up to a certain point; in a proportion which is nearly the mean ratio between the square and cube roots of the length of the bore. It is found that the velocity given by long guns is reduced to an equality Avith that of short guns within a short distance from the muzzle when fired with similar charges. 6. Would the velocity of a shot be increased by entirely preventing the recoil, or by adding greatly to the iveight of the gun? In neither case would any sensible effect be produced on the velocity. 7. Would the velocity of the shot be increased by using a larger charge of p^der ? Only to a certain point, peculiar to each gun ; by further increasing the charge, the velocity would be gradually diminished; yet the recoil is always increased by an increase of charge. 8. What is the ratio of the velocities of shot, when of different weights but fired icith sim- ilar charges ? The velocities are inversely as the square- roots of their weights. 9. What is the ratio of the velocities of shot of equcd weights when fired with different charges of powder? The velocities are directly as the square- roots of the charp-es. 164 HAND-BOOK OF ARTILLERY. 10. How may the velocity be increased, ivith- out augmenting the charge of powder? By decreasing the windage j the loss of velocity by a given windage being directly as the windage. From ^ to yL is lost by a winchigc of ^'y diameter. 11. What is meant by the time of flight of a shot or shell f The time during which it is passing through the air from the piece to the first graze*. 12. When firing with common shells at 45° elevation, hoio is the time of flight found? Extract the square root of the range in feet and divide by 4; or divide the range in feet by 16, and extract the square-root of this quotient. Note. — Range in feet^^i-y'^x cotangent elevation. =1(3^2X cotangent elevation. =16/2 where the elevation is 45°. Or <=:i|/ range in feet for elevation 46°. 13. Having the time of flight, how is the range ascertained? Multiply the square of the time of flight by 1(3 for the range in feet (the elevation being 45°). 14. What is meant by the penetration of pro- jectiles? The depth to which they are forced when fired into any resisting medium. ] 5. Give the law of penetration of balls. The penetration of balls of the same size, with different velocities or charges, is nearly as the squares of the velocities; where the ?eet. Inches. 8 6 15 4 6 1 10 3 TRACTICAL GUNNERY. 165 balls are of different sizes, the penetration will be ]:)roportionate to their diameters m\\\- tiplied b}^ the density, and inversely' as the tenacity of the medium. 16. Mention the depth of penetration in case of the 24-pdr. siege gun. At 100 yards a 24r-pdr. ball with a charge of one-third of its weight will penetrate as follows : In earth of old parapets, " " recently thrown up, " Oak wood, sound and hard, '^ Rubble stone masonry, " Brick, 17. What is the depth of penetration of shot fired from field pieces ? Fired at the distance of 500 or 600 yards, the penetration will be from 4^ to 6 feet in jDarapets recently constructed, and will tra- verse walls of ordinary construction; but a' IS-pdr. is necessary to make a breach in walls of good masonry and of 4 feet in thick- ness, and in this case the position of the bat- ter}^ must be favorable and the operation a slow one. 18. In attacking a post or fortified position, in what manner should the fire from artillery he carried on ? Previous to an assault, the artiller}- ought to support the other troops by a combined fire of guns, howitzers and small mortars, so that, if possible, the fire may be simul- taneous, as such a diversity of projectiles 166 HAND-BOOK OF ARTILLERY. would teiul to distract the defenders and prevent them from extino-uishinii; any fire amoni^ buildinos, besides throwing; them into confusion at the moment of assault. In eases of surprise, when immediate action is required, the above method cannot, of course, be practicable. 19. When firing guns of different calibres at Jong ranges, what are the probabilities of hitting the object ? As the squares of the diameters of their respective shot, when of equal density, and fired with proportional charges. MISCELLANEOUS. 16' Part XIV. MISCELLANEOUS. 1. What is the velocity of sound in the air ? At the temperature of 83° the mean velo- city of sound is 1,100 feet in a second. It is increased or diminished half a foot for each degree of temperature above or below 33°. 2. Moiv can the distance of an object be ascer- tained by the report of fire-arms? By observing the number of seconds that elapse between the flash and the report of a gun, and multiplying the number by the velocity of sound in the air. 3. What is momentum ? The force possessed by a body in motion ; and is measured by the product of the mass of the body into its velocity. 4. Whe7i equal masses are in motion, what proportion do their momenta bear to their veloci- ties ? They are proportional to their velocities. 5. Wlien velocities are equal, what p>roportion do their momenta bear to their masses ? They are proj^ortional to their masses. 6. What proportion do the momenta bear to each other when neither the masses nor velocities are equal ? They are to each othei* as the products of 168 HAND-BOOK OF ARTILLERY. their masses into their velocities respec- tively. 7. What is the average weight of a horse? Ahoiit 1,000 pounds. 8. What space does a horse occupy in the ranks ; /n a stall ; and at a picket ? In the ranks, a front of 40 in., a depth of 10 feet ; in a stall, from 3j to 4^ feet front; at picket, 3 feet by 9. 9. What are the comparative effects of the labor of a man, and that of a horse or mule ? Taking the useful effect of a man's daily labor as unit}', a horse can carry a load on a horizontal plane 4.8 to 6.1 times; and a mule 7.6 times greater than a man. Taking a man with a wheelbarrow as unity, a horse in a four-wheel wagon can draw 17.5, and in a ^art 24.3 ; and a mule in a cart 23.3 times greater burden. 10. What weight is an artillery horse re- quired to draw ? Not more than 700 lbs., the weight of the carriage included. 11. What weight can a team of four horses or more draw with useful effect ? Includino; the weio-ht of carriaii'o, 4 horses can draw 24 cwt., or 6 each -, 6 horses, 30 cwt., 5 each ; 8 horses, 36 cwt., 4^ each; and 12 horses, 48 cwt., or 4 each. It is usual to estimate the weight of a carriage exceeding 12 cwt. as part of the load. 12. What weights are carried by the riding, pack, and draught horses respectively ? A horse carrying a soldier and his equip- V MISCELLANEOUS. 169 » ments (sa^ 225 lbs.) travels 25 miles in a day (8 hours) ; a pack-horse can carry 250 to 300 lbs. 20 miles a day ; and a draught- horse, 1,600 lbs. 23 miles a day, weight of carriage included. 13. What are the usual paces for horses in the artillery ? Walk, trot and galloj) ; the last is seldom necessary. 14. What is considered an ordinary day's march for field artillery, and rate of motion? An ordinary march is about 15 miles at 2j miles per hour for 6 hours ; this must depend upon the condition of the horses, state of the roads, and various other circumstances; Horses starting fresh, and resting after their work, may, on tolerable roads, perform 2 miles in half an hour; 4 miles in Ih hours; 8 in 4, and 16 in 10 hours. 15. What is the rate of march of horse-artil- lery and cavalry ? Walk, 3f miles per hour, or 1 mile in 16 minutes; trot, 7* per hour, or 1 mile in 8 minutes ; manoeuvring galloj), at the rate of 11 miles per hour, or 1 mile in 5^ minutes; cavalry charge, 24 miles an hour, or at the rate of 1 mile in 2^ minutes. 16. At what rate does infantry march ? In common time, 90 steps=70 yards in 1 minute, or 2 miles 680 yards in an hour ; in quick time,' 110 steps=86 yards in 1 minute, or 2 miles 1,613 yards in an hour; in double- quick, 140 steps=109 yards in 1 minute, or 3 miles 1,253 yards in an hour. 15 Ij^ HAND-BOOK OF ARTILLERY. 17. What space does afoot soldier oa'apy in the ranks, and what is his average 'weight f A front of 20 in., and a depth of 13 in., without the knapsack ; the interval between the ranks is 13 in.; 5 men can stand in a space of 1 square yard. Average weight of men, 150 ll)s. each. 18. What is the daily allowance of water for a man ? One gallon, for all purposes. 19. What is it for a horsed Four gallons. 20. What is the weight of a bushel of oats ; or of wheat ; and the weight of hay ? 40 lbs., or 32.14 lbs. to the cubic foot, in case of oats ; 60 lbs. to the bushel, or 48.21 lbs. to the cubic foot, in case of wheat ; hay pressed in bundles weighs 11 lbs. per cubic foot. 21. What weight does an infantry soldier carry when in marching order ? About 45 lbs. in all. His knapsack when packed weighs 24 lbs. ; canteen when filled, and one day's provisions in haversack, 5 lbs.; rifle-musket, sling and bayonet, 10 2^ lbs. ; belts complete, including 20 rounds of am- munition, 6 lbs. 22. How is the area of a circle found ? Square the diameter, and multiply by .7854 for the area ; or square the circumfer- ence, and multiply by .07958 for the same result. 23. How is the content of a conical frustum found ? MISCELLANEOUS. 171 Adcl into one sum the areas of the two ends and the mean proportional between them ; take one-third of that sum for the mean area, and multiply it by the perpen- dicular height of the frustum for its con- tent. 24. How is the 7nean proportional found for the above ? By multiplying the areas of the two ends together and extracting the square-root of their product. A more simple rule is the following: As the diameter of the large end is to that of the small end, so is area of base to mean proportional required. 25. How is the content of a spherical segment found ? From three times the diameter of the f-phere take double the height of the seg- ment, then multiply the remainder by the square of the height, and this product by .5236 ; or, to three times the square of the radius of the segment's base add the square of its height, then multiply the sum by the height, and this product by .5236, for the content. 26. How is the capacity or content of a Gomer chamber computed ? This chamber being the frustum of a cone with a hemispherical bottom, its capacity will be found by applying the foregoing rules, viz : first find the content of the frus- tum, then that of the spherical segment or bottom, and add their contents into one sum for the capacity. VIZ HAND-BOOK OF ARTILLERY. 27. How is the content of a rectangular box ascertained ? Multiply the length b}' the breiidlh, and this product by the depth. 28. How is the capacity of a cylinder calcu- lated f Multiply the area of the base by the height. 29. How is the content of a barrel found f Multiply half the sum of the areas of the two interior circles, taken at the head and bung, by the interior length; or, to the area of the head add twice the area at the bung, multiply that sum by the length, and take one-third of the product for the content. 30. What is meant by the term enfilade ? Sweeping the whole extent of a work, line of troops, deck of a ship, etc., with shot or shells. 31. What does defilade mean ? The art of disposing guns, troops, or works in such a manner that they shall be protected from a plunging fire from adjoin- ing heights. 32. What are the dimensions required for an earthen parapet to j^esist the fire of field or siege guns ? 6 feet for 6-pdrs.; 14 feet for IS-pdrs.; 18 feet for @4 or 18-pdrs. Four feet of oak or brick will resist cannon shot. 33. "What thickness of ice will admit the passage of infantry, cavalry^ and artillery ? Ice three inches thick will bear infantry marching in file; from \\ to 6^ inches, cav- MISCELLANEOUS. 17 /o airy and light artillery; and beyond that the heaviest gim-carriages may pass in safety. Ice 8 inches thick will bear nearly 10 cwt. upon a square foot without dano^er. 84. How is the size of a rope designated'? ^y its circumference : thus, a two-inch rope is a rope two inches in circumference. 35. How is the strength of a hemp rope, or the weight it luill support, ascertained ? Square the circumference in inches, and divide by 5, for the weight in tons that it will bear suspended from it. 36. How can the breadth of a river he ascer- tained ivithout instruments ? As follows : Fig. 6. 1st. The line ^g (the distance to be deter- mined) is extended upon the bank to B, from h(^ HAND-BOOK OF ARTILLERY. wliicli point, after having marked it, lay off equal distances DC and CJ ; produce BCio b, making Ch=CB ; tlien extend the line db until it intersects the prolongation of the line CA at a. The distance ab is equal to AB or the width of the river. 2d. Lay off any convenient distance, BCj perpendicular to AB, erect a perpendicular DC to AC, note the point D where it in- tersects AB produced; measure BD ; then AB=: BD: 37. IIoiv can the breadth of a rive?' be ascer- tained by means of the peak of a cap, or cocked hat? Place 3^ourself at the edge of one bank and lower the peak of the cap, or point of the hat, till the edge cut the other bank, then steady your head hy ])lacing your hand under your chin, and turn gently around to some level spot of ground on your own side of the river, and observe where your peak or point of jonr hat again meets the ground ; measure this distance, which will be nearly the breadth of the river. 38. How do you ascertain the distance of an object by means of the tangent-scale of a gun, the height of the object at the required distance being known ? Direct the line of metal of the gun on the top of the object; then raise the tangent- *The second method was suggested to me by Oai»hiin Vogdes, 1st Artillery, U. S. Army. MISCELLANEOUS. 175 slide till the top of it and notch on the muz- zle are in line with the foot of the object, and note what length of scale is required ; then by similar triangles, as the length of the raised part of the tangent-scale is to the length of the gun so is the height of the dis- tant object to the distance required. 39. What composition may he used for greas- ing the axle-trees of artillery carriages ? Hogs' lard, softened by working it. li this cannot be procured, .tallow or other grease may be used ; if hard, it should be melted with fish-oil. 40. What is the simplest method of bursting open strong gates ? Suspend a bag of gunpowder containing 50 or 60 lbs. near the middle of the gate, upon a nail or gimlet, having a small piece of port-fire inserted at the bottom, and well secured with twine. 41. What is the length of a pendnlinn to vibrate seconds^ half and quarter seconds re- spectively ? Seconds, 39.1 inches ; half seconds, 9.8 inches; and quarter seconds, 2.45 inches. 42. Give a formula for determining the length of the seconds pendulum in any latitude. 1= [32.1803 feet— 0.0821 cos. 2 lat.] 9.8696044 "■ "^ 43. How are the times of a single oscillation of two pendulums to each other ? As the square-roots of their lengths. 176 HAND-BOOK OF ARTILLERY. 44. Repeat the table of measures. 10 tenths .1 inch. 4 inches 1 hand. 12 inches .1 foot. 28 inches 1 pace. 3 feet 1 ytird. 2 yards 1 fathom. 220 yards 1 furlong. 1,760 yards . ... . . 1 mile. 45. Repeat the table of avoirdupois weight. 47.34735 grains 1 dram. 16 drams 1 ounce. 16 ounces .1 pound. 2^ lbs 1 quarter. 4 qrs., or 112 lbs 1 cwt. 20 cwt 1 ton. In some of our states the ton is estimated at 2,000 lbs. 46. What is the force of gravity ? It is that force of attraction exerted b}- the earth upon all particles of matter which tends to urge them toward its centre. 47. What is the. specific gravity of a body ? The ratio of the weight of a body to that of an equal volume of some other body as- sumed as a standard, usually pure distilled water at a certain temperature. 48. What is the law of descent of falling bodies ? The spaces fallen through from the com- mencement of the descent are proportional to the squares of the times elapsed. 49. What compositions are made use of for ^preserving iron camion ? 1. Black lead, pulverized 12 Red lead 12 Litharge ........ 5 Lampblack ....... 5 Linseed oil 66 MISCELLANEOUS. lit Boil it gently about twenty minutes, dur- ing which time it must be constantly stirred. 2. Umber, ground 3.75 Gum shellac, pulverized .... 3.75 Ivory black .^.75 Litharge 3.75 Linseed oil 78 Spirits of turpentine .... 7.25 The oil must be first boiled half an hour; the mixture is then boiled 24 hours, poured oif from the sediment, and put in jugs, corked. 3. Coal tar (of good quality) ... 2 gals. Spirits of turpentine. . . .1 pint. In applying lacker, the surface of the iron, must be first cleaned with a scraper and a wire brush, if necessary, and the lacker ap- plied hot, in two thin coats, with a paint- brush. It is better to do it in summer. Old lacker should be removed with a scraper, or by scouring, and not by heating the guns or balls, by which the metal is injured. About 5 gallons of lacker are required for 100 field guns and 1,000 shot; about^l quart for a sea-coast gun. Before the lacker is ap- plied, every particle of rust is removed from the gun, and the vent cleared out. 50. How many gallons does a cubic foot con- tain ? 7.48 gallons. 51. What is the weight of a gallon of dis- tilled water ? At the maximum' density (39°. 8 Fahr.), the barometer being at 30 inches, it weighs 178 HAND-BOOK OF ARTILLERY. 8.33888 avoirdupois 2)ouncls, or 58873 troy grains. 52. What are the different lengths of 2)hnn- metsfor regulating the march of infantry? Common time 90 steps in a minute, 17.37 inches. Qui. k time 110 '' " 11.6 inches. Double-. (uirk 140 " " 7.18 inches. ^3. HoiLi is a plummet made ? By means of a musket ball, suspended by a silk string, upon which the required lengths iire marked; the length is measured from the point of suspension to the centre of the ball. 54. Explain hoiv to embark and disembark artillery and its stores. 1. Divide the total quantity to be trans- ported among the vessels, and place in each vessel everything necessar}^ for the service required at the moment of disembarkation, so that there will be no inconvenience sliould other vessels be delayed. 2. If a siege is to be undertaken, place in each vessel with each piece of artillery its implements, ammunition, and the carriages necessaiy to transport the whole or a part; the platforms, tools, instruments and mate- rials for constructing batteries; skids, rollers, scantling and plank. 3. If a particular calibre of gun is neces- sary for any operation, do not place all of one kind in one vessel, to avoid being en- tirely deprived of them by any accident. 4. Dismount the carriages, wagons, and limbers, by taking oif the wheels and boxes, and,, if absolutely necessary, the axle-trees. MISCELLANEOTJS. 179 Place in the boxes the linch-pins, washers, etc., with the tools required for putting the carriage together again. Number each car- I'iage, and mark each detached article with the number of the carriage to which it be- longs. 5. The contents of each box, barrel, or bundle should be marked distinctly upon it. The boxes should be made small for the con- venience of handling, and have rope handles to lift them by. 6. Place the heaviest articles below, begin- ning with the shot and shells (empty), tiien the guns, platforms, carriages, wagons, lim- bers, ammunition-boxes, etc.; boxes of small arms and ammunition in the dryest and least exposed part of the vessel. Articles required to be disembarked first should be put in last, or so placed that they can be readih^ got at. If the disembarkation is to be performed- in front of the enemy, some of the field pieces should be so placed that they can be disembarked immediately, with their car- riages, implements, and ammunition ] also the tools and materials for throwing up tem- porary intrenchments on landing. 7. Some vessels should be laden solely with such powder and ammunition as may not be required for the immediate service of the pieces. 8. On a smooth, sandy beach, heavy pieces, etc., may be landed by rolling them overboard as soon as the boats ground, and hauling them up with sling-carts. APPENDIX. RIFLE CANNON. 1. What is a rifle? A fire-arm having a number of spiral grooves cut into the surface of its bore, for the purpose of giving the projectile a motion of rotation about a line coinciding with the direction of its flight. 2. What are the advantages of this rotation? It increases the range of the projectile by causing it to move through the air in the direction of its least resistance, and corrects the cause of deviation by distributing it uni- formly around the line of flight. 3. What projectiles promise to be ynost suc- cessful for heavy guns ? They may be ranged under two heads, viz: 1st. Those which have flanges or projections on them to fit into the grooves of the gun in loading, the flanges being of a softer metal than the body of the projectile. 2d. Those constructed on an expanding principle, the body being generally of cast-iron and the expanding portion being a band or cup of some softer metal, as peivter, copper or ivrought- iron, which enters the bore of the piece free- ly in loading, but which is forced into the grooves by tlie discharge. APPENDIX. 181 4. What determines the form of the spiral grooves ? The angle which the tangent line at any point makes with the corresponding element of the bore. If this angle be the same at every point^the groove is said to be uniform. If it increases from the breech to the muz- zle, the groove is called increasing; if the reverse, decreasing. 5. Describe the different modes of cutting the grooves. 1st. The barrel may have botli a motion of translation and rotation, whilst a station- ary cutter presses upon it. 2d. The barrel may have only a portion of rotation while the cutting point is given a motion of trans- lation. 3d. The barrel may remain station- ary, and the point have both motions. 6. Which of these is the practical method of rifling a gun ? The last; a rod armed with a cutter is moved by machinery back and forth in the bore, and at the same time revolved around its axis. If the velocities of translation and rotation be both uniform, the grooves will be uniform; if one of the velocities be varia- ble, the grooves will be either decreasing or i?icreasing, depending on the relative veloci- ties in the two directions. 7. What is understood by the term twist? It is* employed by gun makers to express the inclination of a groove at any point, and is measured by the tangent of the angle 182 APPENDIX. made by the groove -svith the axis of the bore. 8. To what is this tangent equal? To the quotient obtained by dividing the circumference of the bore by the length of one revolution of the spiral estimated in the direction of the axis. * 9. Has the most suitable inclination of grooves for a rifle cannon yet been determined ? No \ a wide diversity of twists is employ- ed by different experimenters. 10. Describe the Armstrong gun. It is a breech-loading rifle cannon, com- posed wholly of wrought-iron, the promi- nent feature in its manufacture being the combining into one mass of iron bars, which are first coiled into spiral tubes, and then welded by hammering. From the muzzle to the trunnions the gun is made of one thickness, but in rear of the trunnions two additional layers of material are applied. The rear end of the gun receives a screw, which presses against a movable plug or stopper for closing the bore when the gun is loaded. The vent is contained in this stopper. The screw is hollow, and turned by a handle. When the stopper is removed, the passage through the screw may be re- garded as a prolongation of the bore. The iiore is 3 inches in diameter, and is rifled with 1 hirty-four small groo*ves. It is widened at the breech one-eighth of an inch, to enable the projectile to enter freely and choke at the commencement of the grooves. The projectile is an elongated one, made of cast- APPENDIX. 183 iron thinly coated with lead ; and being of somewhat larger diameter than the bore, the lead is crushed into the grooves, thus secur- ing the necessary rotation whilst all shake and windage is prevented. The process of loading is eifected by placing the projectile, with the cartridge and a greased wad, in the hollow of the breech-screw, and thrusting them, either separately or collectively, by a rammer into the bore. The stopper is then drojiped into its i:)lace, and secured by turn- ing the screw. The gun is fired by the ordi- nary friction*tube. The greased wad renders unnecessary the use of a sj^onge. The largest gun which has 3'et been con- structed is one of 65 cwtf and throwing a shot weighing upward of 100 lbs. The greatest range yet attained by the Armstrong gun is nearly 5i miles. The range of the Armstrong 12-pdr. field gun of 8 cwt., at an elevation of 5°, and with a charge of 1 lb. 8 oz., is about 1,920 yards. Projectiles have been fired from this gun through a mass of oak timber 9 feet in thickness. Note. — The foregoing description of the Armstrong gun is condensed from the 5th edition of Sir H. Douglass' Naval Gunnery, to which the reader is referred for a com- plete description of the gun and projectile. The following table presents a synopsis of the results in case of some of the rifle cannon tested at Fort Monroe, in 1859, by a Board composed of Ordnance and Artillery olfi- 184 APPENDIX. .Target Bore. Grooves. Name. Calibre. Twist. J Width. Depth. a Q J >5 ill. in. in. ill. Sawyer 24-in-. 5.862 110 6 1.5 0.25 Uniform, one turn in U% feet. Dimick 32-i)r. 6.4 101 6 2.0 0.2 re^tan. Incrciisin-i; from to one turn in 6-2}A ft. at muzzle; twist to the risht. Dr. Reed- 12-pr. S"gc. 4.854 109 l-14th circum. .03 to .08 Increasing from at commencement to one turn in 50 feet at muzzle. Do. ... 12-9r.Field 4.636 74 7 do. do. Do. do. Do. ... 32-i)r. 6.425 110 3 l-6th circum. .085 to .12 circiUar. Uniform, one turn in 40 feet. Do. ... G-pr. 3.69 103.4 3 do. .077 to .111 circular. Uniform, to the right one turn in 25 feet. Capt.Dyer. 3-pr. 2.9 44.5 8 0.4 .05 Uniform, one turn in 16 feet, Unifoi%. one turn in Do. ... C-pr. b'uze. 3.67 57.5 16 0.5 .025 1 19 feet. The following is the description of the several projectiles, viz : Sawyer's. — Flanged projectile; elongated; entire shell coated with an alloy, chiefly of lead, and has a percussion-cap on small end. Bimick's. — Expanding shell; elongated; cup of soft metal cast on rear end of projectile. Reed's. — The body is of cast-iron, and the expanding portion is a cup of wrought-iron, which is fastened to the body by iuserting it in the mould and pouring the melted met- al around it. Dyer's. — Description nearly the same as that of Dimick's. 4 0' BY 2 0'. APPENDIX. 185 a 9 o •s 1 Ihs. 8822 9300 5000 1900 8500 1200 250 880 o 1 to I lbs. 45 51 22 15 50 12 9 14 t 1 lbs. 6 3 2 6 1 1,000 Yards. 2,000 Yards. 6 a ^yn mw %mr' i^ womt ^m m/ w