IMIM _ CA/V>^CS THE LIBRARIES COLUMBIA UNIVERSITY Qv* Jr' At m Avery Library i iW I 1 1 1 I 1 I i I I 1 BUILDING CONSTRUCTION FOURTH SERIES Including an Inexpensive Method ol Directing Daylight Back into Dark Interiors or Rooms BY . PETER H. JACKSON PACIFIC COAST AGENTS Baker Iron Works, - - 950-966 Buena Vista Street Los Angeles, Cal. Chas. A. Palm, - 1119 Sixth Street Sacramento, Cal. C. H. Brown & Co., - 76 First Street Portland, Oregon C. H. Brown & Co., - - - - 322 Bailey Building Seattle, Wash. Copyright 1809 by Peter H. Jackson EASTMAN & THOMAS, PRINT, 416 MARKET ST., S. F. ...CONTENTS... Improvement in Combined Sidewalk and Root of Vault Construction. Advan- tages: Increased Room, Finished Ceiling, Lighter Steel Beams, etc., at no increased cost over common method ....... Solidity in Fire-Proof Floors of Light Weight, Tying and Bracing the Walls from end to end at each floor. Enlarged Blue Prints on application. Transmission of Daylight from Windows and Other Places to Light Back into Dark Interiors or Rooms ......... Mammoth Prism Lens, Sidewalk Lights and Aprons, Unequalled for Transmitting Daylight Back into Dark Basements ........ Ventilation of Basements .......... California Sate Deposit and Trust Co’s Rooms Under Sidewalk, also Rear of said Building ............ Under the Sidewalk of the Claus Spreckels iS story Building, occupied as the Press-room of the “San Francisco Daily Call” . Floor Lights ............. Illuminating Stoop ........... Cement or Stone Illuminating Vault Covers and Rims ..... Exterior of a Large Arched Skylight ...... Sidewalk Lights ........... Panels of Arched Skylights ......... Iron Illuminating Vault Cover and Rims, also Coal Hole Covers . Architectural Iron and Steel Work for Buildings .... PAGE I to 5 6 and 7 8 to 10 . 1 1 and 1 2 13 and 14 15: 17 18 16 and 18 19 19 20 21 and 22 23 23 24 All Steel Flush Water-proof Sidewalk Doors and Steel Frames 25 and 26 JACKSON'S COMBINED ARTIFICIAL STONE SIDEWALK AND GALVANIZED STEEL ROOF OF VAULT CONSTRUCTION TOGETHER BUT 4 INCHES IN THICKNESS The bottom surface of sidewalk forming a finished Galvanized Steel Ceiling to the room or vault beneath which, as to finish would be suitable for any ceiling of the building The dove-tail corrugations in the steel bottom form retaining channels which hold and clasp the superposed Artificial Stone filling forming the sidewalk and becomes integral with it, and together of great strength. It was found from trials of strength of several slabs, each 4 inches thick, 7 feet long, span 6 feet 6 inches, and 1 foot 8 inches wide, the average breaking distributed load was 2221 pounds per square foot. The San Francisco City Ordinance requires the strength of sidewalks over vaults to be 400 pounds per square foot, or less than one-fifth this strength. ADVANTAGES It increases the room from floor to ceiling from 12 to 15 inches compared to any other con- struction and without additional expense. It saves in cost by using lighter steel beams than when the usual heavy brick or concrete arches are used. In many of the streets in San Francisco the street sewer is not deep enough for requisite I height of closets, etc., under sidewalk. This construction admits from 12 to 15 inches more room up from the floor than the common method. It is particularly adapted to places that will not admit of deep excavation before coming to water. This galvanized steel ceiling or metal bottom of sidewalk, is the same as the galvanized steel bottoms of our Patent Sidewalk Lights, which we have made over 140,000 feet during the last ten years, and are in use in all the Cities of the United States on the Pacific Coast, and in a great many damp and exposed places, and we have yet to learn of a single case of rust . THE FOLLOWING BUILDINGS IN SAN FRANCISCO AND OAKLAND, CAL., HAVE THIS IMPROVEMENT : 1140 to 1146 Market Street 32 Kearny Street 224 to 234 Powell Street 314 to 320 Mason Street hi to 123 Third Street and extending down Stevenson Street S. W. corner Kearny and Commercial Sts. Hall of Justice, Kearny Street 122 to 128 M Smith’s Cash Store, 23 to 27 Market Street 415 to 423 California Street 31 to 37 Turk Street 20 to 24 Geary Street Stockton St., between Clay and Sacramento Sts. 175 feet long on Stevenson Street, beginning at 5th Street S. E. cor. Montgomery and Sutter Streets Street, and others. To be at new fire-proot building N. W. corner Kearny and California streets. Oberon Concert Hall Building, O’Farrell street. u buildings on Fourth and Morrison streets, Portland, Oregon. “ building, N. W. corner 2d and Minna Sts., San Francisco. OAKLAND, CAL. Oakland Bank of Savings in part, 416 to 420 Twelfth street, Uhl building, 13th street near Clay, and others. To realize the advantage and finish of this improved construction it should be viewed from beneath. P. H. JACKSON Sc CO., 228 Sc 230 First St., San Francisco, Cal. From photo taken under sidewalk, from daylight through sidewalk lights of building 1140 to 1146 Market Street, San Francisco, Cal , showing the finished Galvanized Steel Ceiling and Reflecting Lens Sidewalk Lights. The thickness of combined sidewalk and vault roof 4 inches. Strength of sidewalk over 2000 pounds per square foot. Specification on 5th page. From photo taken under 1st floor or basement of above building 25 feet distant back from the sidewalk lights from daylight coming through said lights at that distance, showing in the distance the finished Galvanized .Steel Ceiling and Reflecting Lens Sidewalk Lights, and No Li t/: to Basement, flush steel sidewalk doors. The gutters in frame being steel never break from impact of boxes etc., passing through common to brittle to cast iron. 2 From photo taken under sidewalk of the then unfinished building S. E. corner Montgom- ery and Sutter Streets, San Francisco, Cal., belonging to the Luning Estate, from daylight coming through sidewalk lights above, showing the finished Galvanized Steel Ceiling and Sidewalk Lights supported by Jackson’s Patent Concrete Beams. The thickness of Combined Sidewalk and Roof of Vault 4 inches. Strength of sidewalk over 2000 pounds per square foot. Spec- ification on 5th page. —3178 Prom photo taken under sidewalk of building S. W. corner Kearny and Commercial Streets, San Francisco, Cal., from daylight throught sidewalk lights above, showing finished Galvanized Steel Ceiling and Sidewalk Lights. The thickness of combined sidewalk and vault roof 4 inches. Strength of sidewalk, over 2000 pounds per square loot. 3 From photo taken under sidewalk of the Kearny Street front of the unfinished Hall of Just building, San Francisco, Cal., Mess. Shea& Shea, Architects; showing bottom surface of sidewalk a finis! Galvanized Steel Ceiling. The thickness of Combined Sidewalk and Vault Roof, 4 inches. This constr tion extends the length of block on Kearny Street and down Washington Street. Strength of sidews over 2000 pounds per square foot. Specification on 5th page. SPECIFICATION OF Jackson’s Combined Artificial Stone Sidewalk and Galvanized Steel Ceiling of Basement Extension or Vault Beneath Furnish and Set Artificial Stone Sidewalk with galvanized corrugated steel bottom forming finished ceiling to the room or vault beneath, together 4 inches in thickness, composed as follows: The bottoms to be No. 22 Apollo Best Bloom, or other equally as good galvanized sheet steel having dove-tailed corrugations forming retaining channels for the superposed cement filling, and made as follows: The corrugated sides of one sheet lapping into the adjoining one as shown at (A), see above cross section, and the ends of the corrugated sheets over the beams extending and lapping into each other 3(2 inches or more, the lap covering the width of the beam, the top piece over- lapping in direction of the incline of the street. The middle of spaces between beams to support the middle of the corrugated sheets to prevent vibration during tamping of the cement filling, to be temporarily braced in cross direction to the corrugations, the braces not to be removed before 9 days after completion of cement filling. The corrugated steel bottoms to have a superposed thickness of 4 inches, composed as follows shown in above cross sections: the proportions described in measures, to be first quality slow setting Portland Cement, to be thoroughly mixed with its aggregates and proper proportion ot water, worked quickly, and to be gently but thoroughly tamped, and not stopping work in any event until the full thickness of 4 inches is formed. The bottom thickness to be iff inches completely filling the corrugations 1 J inches deep and of an inch over the flat portion between corrugatious to be 1 of Portland Cem- ent. 2ff of clean sharp sifted beach gravel well mixed with water; if this surface is not very moist before next mixture is applied, coat it with a solution of neat Portland Cement and water of a consistence of very thick cream, upon this to a thickness of 2 inches to be quickly added a mixtureof 1 part Portland Cement, 3 parts of clean sharp sifted beach gravel, 4 parts of clean small broken blue rock that will pass through a 5 + inch mesh, No. 3 rock, and water. (Red Rock Prohibited.) The top half-inch to be equal parts Dyckerhoff or other equally as good Portland Cement and clean sharp sifted beach gravel; the top finished with neat Portland Cement colored to suit, and trowel finished laid off in squares not to exceed two feet, the incisions forming the squares in all cases to be Vi inch in depth. Two galvanized wires twisted into one to be laid about 1 inch below the finished top surface direct and across and not to exceed 20 inches apart in either direction. The top surface to be covered after 20 hours old to a thickness of about one inch with clean sand, and then covered with boards for ten days, and to be kept continually wet during that time. 1 he spaces beneath, between the corrugations in steel ceiling directly over the beams, to be filled in the full width of flange of beam of a mixture of 3 gravel and 1 cement, and troweled smoothly. If an} 7 of the laps beneath are found open, to be filled and pressed in with India Rubber Cement. The temporary braces beneath, to be removed not less than 9 days after completion of sidewalk. The steel ceiling to have two coats of best white paint. The sidewalk lights to have galvanized steel bottoms with dovetailed corrugations blocked with 2V2 inch diameter lenses, and artificial stone filling to be equal parts Portland Cement and fine sifted beach gravel, surface neat cement, bottom painted 2 coats of white paint. for ventilation , large basement ventilators with suspended enameled non-corrosive drip- ping pans to be built in sidewalk near retaining walls and to be not over ten feet centers. Jackson'' s No Leak to Basement , flush with sidewalk, all steel frame sidewalk doors with steel surrounding and steel middle gutters, with drain pipe to extend through retaining wall, and to have chains and fastenings complete. SOLIDITY IN FIRE-PROOF BUILDINGS JACKSON'S 1899 PATENT IMPROVED STROCTORAL FIRE-PROOF CONSTROCTION HR sidewalls of a building having this light in weight, but strong and solid fire-proof construction between, are firmly held by the structural parts in their relative positions to each other by being both braced and tied throughout the distance between, stiffen- ing the building in cross direction. The ends of the light concrete beams or bearers (C) usually about seven feet from center to center, abut and press against the webs of the steel supporting beams (A, A), the metal strip ties (B), which support the concrete bearers, are attached to the sides of the steel beams about the middle of their depth, supported upon the clamps (G.) An especial feature of this improvement after the concrete bearers (0 are hard and strong, by screwing up the nuts . Then place No. 22 dove-tail galvanized corrugated steel sheets to form floor, each of a length extending over and resting on the concrete bearers, of form and size corrugations, etc., shown in the Allowing section Figure 4 1 2 . The sides of the corrugations lapping into each other one full corrugation ; is shown at (A), and the ends of the corrugated sheets extending into each other one or more inches. In the middle of all corrugated sheets and directly beneath them, crossing the corrugations, to be a temporary stiff wooden brace extending their length to stiffen the middle of the corrugated sheet during tamping of the concrete. The concrete mixture to completely fill the corrugations and % of an inch above covering the flat surface between corrugations, making a thickness of 1 V 2 inches from bottom of metal as shown in Figure 4^2, and to be a mixture of 1 measure Portland Cement, 2pj measures of sand, and requisite quantity of water, and to this is to be immediately added a mixture 1 inches in thickness composed of 1 measure of Portland Cement, 2 measures of clean, sharp beach gravel, and 5 measures of cinders, all to be thoroughly mixed and manipulated during the process of the work, and to be thoroughly tamped. This concrete slab is now 3 inches in thickness, and after 8 days old, beveled wooden strips ib inches in thickness shown in Fig. 4 V2, and 18 inch centers, are to be placed by carpenter contractor, after which a concrete filling composed of 1 measure Portland Cement, 3 measures of sand, and 8 measures of cinders, to be filled in even with the top of wooden strips and thoroughly tamped in place. The wooden braces and boards at sides of bearers to be removed 9 days after the concrete filling has been completed. FIRE-PROOF CEILINGS Phider all floors and galleries, soffits of stairs, and under all roof rafters, to be formed a ceiling with cove corners, formed of 1 inch x 1 inch x x s inch steel bent to radius of cove corners, suspended by means of hook bolts spaced 14 inches centers, to which either expanded metal, or wire lathing imbedded in cinder concrete, securely wired; all ceilings to be ready for plaster. A VALDABLE DISCOVERY DIFFUSION OF LIGHT THROUGH WINDOWS AND TRANSMISSION OF LIGHT IN DARK PLACES. The upper sashes of all deep rooms not well lighted at a distance back from the windows, should have simple ribbed glass in true curves, inverse and obverse 21 ribs to the inch. This form of glass is largely in commercial use for certain purposes, and is also the cheapest type of glass for glazing windows except the common clear glass, and is to he had in this market. The ribbed portion on inside and is easily kept clean. Abstract from the Fngineering News and American Railway Journal oj /tec. 22 , iS()S , and substantiated by circular No. 72 of the Boston Manufacturers Mutual Fire Insurance Co., one of which we have. Mr. Edward Atkinson, president of the Boston Manufacturers Mutual hire Insurance Company, experimented largely on the best means of diffusion of light through windows and skylights in mills and factories. He experimented with various forms of glass, including prismatic, corrugated, rough, waved, and ribbed glass, photographed images from each kind, also from plain glass, and he found that the greatest and most uniform diffusion of light was not delivered from prismatic or angular forms but from simple ribbed glass in true curves, inverse and obverse 21 ribs to the inch. This form of glass was fortunately in commercial use, and is also the cheapest for win- dows except the common clear glass. Mr. Atkinson desired further information; again in 1S9S, Prof. C. L. Norton of the Massachusetts Institute of Technology, Boston, Mass., made a more complete investigation, and the report was made in July 19, 189S, by circular 72 of the Boston Manufacturers Mutual Fire Insurance Co., is as follows: Mr. Norton started out doubting the assertion made, that more light was admitted in a room when glazed with corrugated glass than glazed with plain glass. But experience has clearly shown that, at the rear wall of a room 25 feet deep the light was increased three times by substituting ribbed glass for plain glass. The result of this examination to determine the relative intensity of illumination in a room of the various glasses, of which he tested many kinds, in fact all he could find, including the most expensive Cathedral Glass, and the Luxfer Prism Glass, proved that the cheap, Factory Ribbed Glass about 3-16 of an inch thick with 21 ribs to the inch, known as Factory Glass is decidedly the best dispersive glass upon the market. There is no apparent gain by corrugating both sides. Ground glass is a loss of transparency caused by a slight amount of moisture or dust. Photometric measurements were made by taking two rooms one above the other, alike in exposure, shape and size, and comparing the intensity of light falling on similar portions of the two, when one was glazed with plain glass and the other with glass under examination. These following two photographs do not shoiv as great a difference as does the e} 7 e. Take for instance the apparatus case in the upper right hand corner, where ribbed glass is used it is possible to distinguish and recognize the separate pieces with a very small window. When the same window of plain glass is used, one cannot even see that there is any case there. In the photograph the windows are behind the camera, as is shown by the strong light on the lower corner of the plain exposure. RIBBED GLASS PLAIN GLASS These Two Photographs taken from the Photos in Circular No. 72 mentioned, do not show as marked difference as to light as in the circular. Broadly speaking it was found that in the center of the room was as bright when lighted by a "window one square foot of this ribbed glass as with three square feet of plain glass. This was true in all lights from bright sunshine to a heavy thunderstorm,, and windows facing in any direction. In the back office of our place, 228 and 23a First St., this city, is a sash door opening into the back yard, and in it are 8 panels of window glass 12x17 inches, 4 of the glasses were taken out and substituted 4 of these corrugated Ribbed Factory Glass which costs eleven cents per square foot, and have two separate window shades to cover and uncover each the factory and plain glass- Directly opposite this is an open door to a dark room which intervenes between the back office and the front show room, and when all shades are drawn down then the shade over the 4 plain glass is raised the light is feeble 011 the back wall of the dark room about 22 feet distant from the glass door, but when this shade closes out this light and the one over the factory glass is raised the light is bright on the wall. The contrast is surprising and should be witnessed by every architect in San Francisco. d he value of this discovery is very important as we have at hand a cheap reflecting glass' which should be generally used in upper sashes, as illustrated on proceeding page and other places where it is desired to project light into dark interiors, and can easily be kept clean as^ the ribbed portion is 011 the inside and not exposed to damp fogs and dust common to that of other much more expensive kinds that are suspended outside the window. The Following Illustrates the Best Method of Introducing Daylight into Dark Underground Rooms The cut on top of this sheet represents the top surface of a panel of onr improved side- walk lights, that at the right is a cross section of same, and the two cats beneath represent the front and side (enlarged views) of one of onr Mammoth Reflecting Prisms used in said light panel. steel beam on line of front of building, with a suspended apron of ribbed reflecting glass in frame (A) for transmitting back the mass of directed light received on it from the Mammoth Reflecting Prisms. Our Mammoth Prisms have no equal for reflecting light, are set in heavy metal frame bottoms, and cemented with Portland Cement, forming the top surface of glass with artificial stone between, and the aprons of glass we use are superior for transmission of light to any known, and are verified as follows These Mammoth Prisms will light a room back 50 or more feet, and to light back an increased distance aprons (A) are suspended in frames between the front basement columns. The apron is filled with ribbed sheet glass 21 ribs to the inch, inverse and obverse, and as stated by Prof. C. L. Norton of the I Massachusetts Institute of Technology of Boston in his report of many trials made, A superior for I dispersion of light to any other known form of glass, superior to prism glass, see the article headed diffusion of light through windows page 8 of this series. We will furnish these aprons at 30 cents per square foot, while the price here of the best of the several Eastern makes for an inferior article, is $1.75 per square foot, or nearly six times greater. Architects and others are requested to examine the increased reflected light in basement from onr Mammoth Reflecting Prisms in the sidewalk light in contrast with the Chicago Lnxfer Prism Light, both the same size panels, at Hastings Clothing Store, S. W. corner Montgomery and Sutter Streets this city. The introduction of a flood of daylight into the dark parts of our basements under stores where I property is valuable means money, and an increase of cost for that purpose is a wise expenditure. W ei have right here at hand the means for better diffusion of daylight in basements that can be obtained else-jl where at less cost. From “ Building Review ’’ of San Francisco, Cal., January 26th, iSqq. GIANT REFLECTING LENSES Do you want to see Mammoth Light Reflecting Lenses made by a San Francisco firm, and placedib in position by workmen who live here? Then just go down to the corner of Montgomery and Sutterl' Streets at the Hastings Clothing Store. On the Sutter Street side yon will see a specimen of the LuxferJ Prism Co., made in another State. 1 II On the Montgomery Street side you will see Jackson’s Home Product Mammoth Reflecting Lensesi True, there is a comparison, a poodle can be compared to a lion; but, as for the reflecting power of the lenses, the home product is far and away ahead of the Eastern article. And the great superiority is man-| ifest even to the casual observer. Just go in the store and ask to be shown down stairs, an escort wilB be promptly furnished you, and you can at once see the difference. Then, if San Francisco manufacturers beat those of any other city'' in the U. S. why not specify them and see that the}' are used, and thus have the money circulated amongst our own workmen auc storekeepers. The Mammoth Reflecting Lenses are made by P. H. JACKSON & CO., 228 & 230 First St., San Francisco, Cal. JACKSON’S METHODS OF VENTILATING BASEMENT EXTENSIONS, OR SPACES UNDER SIDEWALKS Ventilating carriage block or step to largely ventilate the space under sidewalk. It sets about eleven lies above surface of sidewalk resting on the arch. Length 3 ft. 2 inches. Width 1 ft. 6 inches. Fig. 2 is cross tiou through x-y, Fig. 1. S, indicates sidewalk. The arrows indicate the air escaping from below passing out ough the apertures b. Rain cannot beat in from the outside. This excels any other basement ventilator for ume of exit of air. It is adapted to combined sidewalk and roof of vault construction. It sets just inside the bstoue where carriage blocks are commonly placed. Glass Lens arc inserted in top if so ordered. TUBE VENTILATOR wi th an enameled dripping pan beneath that does not rust which is removable when tilled by drawing out the rods. The arrows indicate the air passing up through and out. C, is the curbstone. R, re- taining wall. S, sidewalk. The piece “P," prevents the pan tipping when full. These are largely used in San PTaneisco, Cal. Sizes 14, 10 and 8 inches, if with 15 galvanized dripping pans larger sizes. ELEVATION HITCHING POST I INCH SCALE VENTILATING HITCHING POSTS BUILT IN THE ARCH AND SIDEWALK NEAR THE CURBSTONE. The figure on the left illustrates the cross section of its length. The air from Base- ment passes up through the bottom and out as indicated by the arrows shown in section. It is adapted to combined sidewalk and steel roof of vault construction and rests on and is secured to brackets built in the retaining wall. In Chinatown, San Francisco they are used in some cases as chimneys, a stovepipe entering the bottom. They are largely used in San Francisco. Jackson’s Steel Water-Proof Sidewalk Doors and steel frame with drain pipe extending through outer wall. The only efficient waterproof construction made. The surrounding gutter of steel is never broken from boxes, etc., striking it in passing through, remedying the fault common to brittle cast iron. >4 The California Safe Deposit and Trust Co’s Building, corner California and Montgomei) Streets, San Francisco, Cal., was erected earl}- in the seventies, and was extensively altered and improved in 1897 hy Henry A. Schulze, Escp, Architect. The following views woe taken hom photographs of some part of the alterations performed by the undersigned. Rear of 1st story of the California Safe Deposit and Trust Co’s Building, San Francisco, Cal., showing Jackson’s Galvanized Steel and Stone Arched Skylight which extends over the rears of first stories on both California and Montgomery Streets. The California Street side, (the Montgomery Street side being the same) of the California Safe Deposit and Trust Co’s Building, San Francisco, Cal., showing the illuminating sidewalk and area covering with ventilators, which light and ventilate the basement extension beneath and basement of the building. With valuable improved business property there is no part of the building that pays sc great a profit on the expenditure as to well light and ventilate the basement extension or space under the sidewalk, and to have the work well executed in every respect. Under surface of either our floor or roof light, glazed with 6 in. x 6 in. heavy poker-dofl glass plates in cast-iron frames. Under the sidewalk lights. The illustration preceding this showed the top surface of sidewalk lights of the California Safe Deposit and Trust Co’s Building; this shows the illumi- nating ceiling beneath. The small rooms shown are the accounting rooms of their patrons. 17 Basement extension or space under sidewalk of the then unfinished Claus Spreckels 18-story building, corner Market and Third Streets, San Francisco, Cal., Messrs. Reid Bros., Archi- tects. From a photograph taken from daylight through the sidewalk lights, showing JacksoiFs Galvanized Steel and Stone Sidewalk Lights having2^ inch diameter round reflecting lenses alter- nating with piano convex lenses. The basement and basement extensioti is the press-room of the San Francisco Call lighted by the sidewalk lights. Under surface of one of our floors or roof lights, glazed with io^ inch square thick, richly ornamented glass plates. Also used for arch and flat skylights'. Enlarged view of a glass further om 1-* Jackson’s Improved Illuminating Stoop with beam risers, tnc risers are of beam strength with nosing cast on as shown, or the nosing may be formed on the tread, the former preferred. These beam risers are made 12 feet or longer between bearers, instead of having bearers every few feet, increasing the cost and obstructing light. The strength of the beam riser is computed by Hodgkinson’s formula for cast iron beams. The ‘.reads, platform, and sidewalk as shown are galvanized steel and stone sidewalk lights. The metal bottoms do not rust and discolor the paint. Iron stairs plain or inlaid of this construction. Daylight and ventilation is indispensable to finished basements of valuable business property. Cement or stone illuminating vault covers and rims. The cover made to lift out or stationary, as Ordered. Sizes, diameter of cover, t8, 24, 30 and 36 inches. T 9 Exterior view of a large Arched Sky Light 35 feet across, unfinished; showing our work- men inserting in the iron frames the \ x / 2 inch thick, ornamented glass plates ioff inches square. An enlarged view of the glass plates which the men are setting shown below. The glass at the left shows the flat top surface, and that at the right is the bottom or inside ornamental surface. These ornamental glass plates are also made up into iron floor lights, and flat roof lights. 20 \ T) I c_ > O 7s CD o 9p O O hrj P o ® < S' p- a c/3 ® p- *-*> o