I 92 opy 1 THE HASTY * PERPETUAL*^ • FOR PRACTICAL USE EYERY BAY*. l^iifM^ THE HASTY PERPETUAL MENTAL CALENDAR, J FOR [ PRHCTICEL USE EVERY MY A SIMPLE, EASY METHOD WHICH WILE EX ABLE AXY OXE. TO DISPEXSE, WITH A PRINTED CALENDAR FOR ALL TIME TO COME. ALSO FI7RXISHIXG A MENTAL CALENDAR FOR EVERY YEAR OF THE CHRISTIAN ERA. VALUABLE IX DE- TECTING OR CORRECTIXG ERRORS IX DAYS. DATES OF MONTHS AXD YEARS. USEFUL TO \\A. Wlh) NEED A CALENDAR, ESPECIAL! BUSINESS MEN, TEACHERS, EDITORS, MINIS- TERS, LAWYERS, ETC. BY E. F. HASTY. ELKHART, - - - INDIANA. 1885. P° [IF W C0 p ;• Entered according to Act of Congress, in the year 1885, in the Office of the Librarian at Washington, by E. F. HASTY, Elkhart, Indiana. ALL RIGHTS RESERVED. ! PREFACE. i#=- 1. This calendar method was invented about five years ago. Two years ago it was perfected, and as many have urged its publication it is now sent out. 2. The method is simple, easily understood, and very little to memorize, especially as regards a large number of persons who are already familiar with some things required. A small degree of earnest attention will enable any one to use it who can understand the simplest tables and examples of arithmetic, and will dispense with the necessity of a printed calendar, in ordinary use, or a calendar clock. A printed Multi- plication Table will be about as necessary for daily use. 3. So far as can be ascertained this is the first time that anything of the kind was ever published; for that reason explanations are rert/ full, especially for the benefit of young people who may desire to learn it : hence the numerous explanations may at first sight make it appear to be a very complicated method, which it is not as may be seen. 4. Whoever is willing to learn the method of find- ing the t; Key Day'' (1st of January) of past and future years, has at command in his head a calendar for every year from 45 B. C. down for 2000 or 300O years to come, and that as really as if he had actually memorized a calendar for each year, so that he can IV PERPETUAL MENTAL CALENDAR. readily and easily tell the day of week of any date, or the date of any special day, when the year and month are given, or can tell anything else that can be learned from a printed calendar. 5. It will be useful to those who instruct the blind, as has been already tested. 6. It will enable any one, in very many cases, to detect, and often correct, errors in days and dates, and also to verify the correctness of others, especially where the day of the week is given. See examples in the back part of this manual. 7. The author claims that this method is entirely original so far perhaps as anything of the kind can be original. He has had no similar method from any source to guide him, or even suggest, and hence no one else is in any sense responsible for its defects, or on the other hand can rightfully share in anything it contains of real merit. PERPETUHL MEHTEL CHLEEDRR, The calendar method, which is explained in the fol- lowing pages, is one in which special importance is attached to what is called, for convenience sake, the " Key Day" of a year. As the "Key Day" must be constantly used in every month and every week of the year, let every one know to a certainty what is meant by it and how to use it. The "Key Day ''' of any year, is always that day of the week which began, or will begin, that particular year. Sunday began the year 1882 ; therefore Sunday is the "Key" for that year. Monday began 1883, Tuesday 1884, and Thursday 1885, and those days are the 4 'Keys" of the respective years: 1886 will begin on Friday, 1887 on Saturday, and 1888 on Sunday, and those will be the "Keys" for those years, in the order named. The principle of this calendar method is. substantially, to have the first date, in each month, of the "Key." so perfectly in the memory that any other date or clay may be quickly found from it. In common years (a common year is any year that is not a Leap Year,) the same set of figures represents the first dates of u Keys v in the different months for all years in all centuries. For example, Sunday is the "Key" for 1882, there- fore the following figures will represent the first dates of Sunday in the months named for 1882, or any other common year of which Sunday is the "Key." The first date of Sunday in January, is 1st; February, 5th; D PERPETUAL MENTAL CALENDAR. March, 5th; April, 2d; May 7th, and June, 4th. The above dates, when put together, make 155,274. That set of figures represents the first dates of Monday in 1883, Thursday in 1885, Friday in 1886, and Saturday in 1887, for the months named above. With the ex- ception of the first two (1 — 5) a different set of figures must be used for all Leap Years, as will be seen here- after. The "Key" for any current year is always known, or can be easily called to mind, but the method for finding the "Key" for any past or future year is explained on pages 14-22 Before further explanations are given, the fol- lowing tables must be memorized and made very famil- iar, or this method cannot be used: TABLE OF MONTHS. 7. July 31 Days 8. August 31 Days 9. September 30 Days 10. October 31 Days 11. November 30 Days 12. December 31 1. January 31 Days 2. February* 28 Days 3. March 31 Days 4. April 30 Days 5. May 31 Days 6. June 30 Days *February has twenty-nine days in any Leap Year. The following, Table No. 1, gives the first date of the ' ; Key ;; for each month in any Common year, and must, therefore, be most used and should be memor- ized and made very familiar: TABLE NO. I. (FOR COMMON YEARS.) Jan, Feb. March. April. May. June. 15 5 2 7 4 July. Aug. Sept. Oct. Nov. Dec. 2 6 3 1 5 3 Table No. 2 gives the first date of the "Key" for each month in any Leap Year, and should also be memorized. PERPETUAL MENTAL CALENDAR. TABLE NO. II. (FOR LEAP YEARS.) Jan. l Feb. 5 March. 4 April. 1 May. 6 June. 3 July 1 Aug. 5 Sept. 2 Oct. 7 Nov. 4 Dec. 2 These tables are for perpetual use, applying to all years in any century. The figures in Table No. 1 make the following num- bers, which may aid in memorizing: 155,274 — 263,153. Table No. 2 makes the following: 154,163—152,742. There must be great care taken to associate the figures with their proper months, and in regular order as in the above tables. EXPLANATION NO. 1. Thursday is the " Key " for 1885, because it is the day of the week which begins the year ; 1885 is not a Leap Year, therefore we use " Table No. 1." The first date of Thursday in each month may be shown thus: January 1st Thursday. February 5th Thursday. March 5th Thursday. April 2d Thursday. May 7th Thursday. June 4th Thursday. Making, as we see, the numbers 155,274, and the dates for the other six months will make the other number 263,153. Take the year 1882, which is not a Leap Year New Year's Day was Sunday, and Sunday is therefore the "Key" for 1882. The figures above represent the first dates of Sun- day in each month of 1882. The same is true of any other New Year's day or " Key Day v for any common year. 8 PERPETUAL MENTAL CALENDAR. 1884 was a Leap Year. Tuesday being the day which began the year is therefore the "Key" for 1884. Hence we must use ''Table No. 2," which may be explained in the same manner as "Table No. 1." The first date of the ;t Key" for any month in the year having been memorized is therefore always known, hence any other date or day may be quickly found as previously stated. TAKE NOTICE !- -Any one who can easily and quickly tell the names of the days, and the dates, of the first seven days of each month, lias orprcome the most difficult part of this method. DATES GIVEN TO FIND THE DAY OF THE WEEK. 1st Example. — Find the day for April 1, 1885. Thursday is Key for 1885. The first date of Thursday in April 1885 is the 2d. (See Table No. 1.) Therefore, if April 2 is Thursday, then April 1. is Wednesday. 2d Example.— Find the day for May 6, 1885. The first date of Thursday in May. 1885. is the 7th. There- fore, May 6th must be Wednesday. 3d Example. — Find the day for June 7, 1885. The first date of Thursday in June, 1885. is the 4th. There- fore. June 7th must be Sunday. 4th Example.— Find the day for July 4, 1885. The first date of Thursday in July, 1885. is the 2d. There- fore the 4th must be Saturday. 5th Example. — Find the the day for Nov. 2, 1885. The first date of Thursday in Nov., 1885, is the 5th. Therefore the 2d must be Monday. PERPETUAL MENTAL CALENDAR. y EXPLANATION NO. 2. TO FIND THE DAY OF WEEK FOR ANY DATE BEYOND THE VII. The numbers 7, 14, 21, and 28, may be designated as full week numbers or dates. Find the difference between the given date and the full week number or date next below; then find the day of the week for that difference. N. B. — If the given date is itself a full week date, 14, 21 or 28, then find the day for the 7th, for whatever day has the 7th has also the 14th, 21st and 28th. 1st Example. — Find the day for September 10 th, 1885. The full week number below the 10th is the 7th. The difference between 7 and 10 is 3 ; therefore find the day for September 3d. The -fiist date of the " Key," Thursday, in September, 1885, is the 3d. Whatever day has the 3d has the 10th: therefore September 10th, 1885, is Thursday. 2d Example.— Find Hie day for October 18th, 1885. The difference between 14 and 18 is 4. Find the day for October 4th. The first date of Thursday in Octo- ber, 1885, is the 1st, therefore the 4th is Sunday, and October 18th, 1885. is Sunday. 3d Example.— Find the day for November 23d, 1885. The difference between 21 and 23 is 2. Find the day for November 2d. The first date of Thursday in November, 1885, is the 5th. Therefore, the 2d is Monday. November 23d, 1885, is Monday also. 4th Example.— Find the day for December 31st, 1885- The difference between 28 and 31 is 3. Find the day for December 3d. The first date of Thursday in 10 PERPETUAL MENTAL CALENDAR. December, 1885, is the 3d. Therefore, December 31st, 1885, is Thursday, for whatever day has the 3d has also the 31st. EXPLANATION NO. 3. THE DAY OF THE WEEK GIVEN TO FIND THE DATE OF THE MONTH. To find the 2d, 3d, 4th and 5th dates of any given day in any month. Find the first date and add to that 7 for the 2d, 14 for the 3d, 21 for the 4th, and 28 for the 5th. 1st Example. — Find the date of the 1st Sunday in March, 1885. We know by "Table No. 1," that the first date of the " Key "—Thursday— for March, 1885, is the 5th. Therefore, the first Sunday in March, 1885, is the 1st day of March. 2d Example. — Find the date of the 3d Tuesday in April, 1885. The first Thursday in April, 1885, is the 2d. Therefore, the first Tuesday is the 7th. Adding 14 to 7 (see rule above) gives 21st for the 3d Tuesday in April, 1885. 3d Example. — Find the date of the 4th Wednesday in September, 1885. The first Thursday in September, 1885, is the 3d. Hence the first Wednesday must be the 2d. Adding 21 to 2 gives 23d for the fourth Wednesday in September. 1885. 4th Example. — Find the date of the 5th Saturday in October, 1885. The first Thursday in October, 1885, is the 1st. Hence the first Saturday must be the 3d. Adding 28 to 3 gives the 31st for the fifth Saturday in October, 1885. PERPETUAL MENTAL CALENDAR. 11 FURTHER EXPLANATIONS AND SUGGESTIONS TO AID IN THE RAPID AND EASY WORKING OF THIS CALENDAR. In order to be able to call to mind very quickly the present date in any month we must have reference to the "Key Date ,? of a month, and be able to know or call up instantly the " Key date " last passed over. After a little practice that will become a very easy thing and one can as readily have at command the month date, as the day of the week. The "Key Dates" for any month are found by adding 7. beginning with the first " Key Date " of a month. The first are given in Tables No. 1 and 2, which are presumed to be most thoroughly memorized. They are the same in January for both Leap Years and common years, as follows: 1, 8, 15, 22, 29. Each particular month in all common years has the same set of " Key dates. "' " Keys " change, but i; Key dates " do not. The same is true of Leap Years. Each month has its particular " Key dates " which never change. The " Key dates " for April in all common years are 2. 9, 16, 23,^30. The "Key dates" for April in all Leap Years are 1, 8, 15, 22, 29. It will, of course, be observed that some months have the same " Key dates " that others have. As the "Key date'' must be used in every week in the ordinary daily use of the Calendar, it will there- fore be found very helpful to fix in the mind, at the beginning of each year, the numbers which may be associated with the days of the week throughout that year, as will be explained below. Those numbers may be very quickly added to a "Key date" in order to 12 PERPETUAL MENTAL CALENDAR. find the desired date of any particular da}', without the more slow process of passing from one day to another, sometimes over five or six days. Examples by way of explanation : 1885. Thursday. •■Key.'" 1886. Friday. " Key." Friday 1 Saturday 1 Saturday 2 S .,nday 2 Sunday '. . . . 3 Monday '6 Monday -1 Tuesday 4 Tuesday 5 Wednesday 5 Wednesday 6 j Thursday .6 In the above if any one desires to know the date of Monday in any month or week of 1885 let him add 4 to the preceding "Key date/" for Tuesday add 5. for Wednesday add 6. etc. For 1886 the figures opposite the several days may be added, and for other years different numbers, until we come again to the same "Keys." Suppose that you have entered upon Wednesday in the last week of January, 1885, and you desire the date. Add 6 to your last "Key date." 22d. which gives the 28th for Wednesday. Or if you desire to know the date of some Wednes- day a week or two in advance, always add 6. or what- ever number may be required for that year, to the preceding "Key date." prodded, of course, that pre- ceding "'Key date" is in the same month with Wednesday or other day whose date you desire to know. If you have in any case forgotten your last "Key date " in any month, you are always supposed to know your first "Key date," and any other one can be quickly found by adding 7. as already explained. It is well to be familiar with the regular week PERPETUAL MENTAL CALEXDAR. 13 number of the days as well as their naines and order, as: Sunday. 1st day; Monday, 2d day; Tues- day, 3d day; Wednesday, 4th day; Thursday. 5th day; Friday, 6th day ; Saturday, 7th day. When the week number, and the month date, of any day are the same.it is very easy to find any day or date required. For example the 1st day of November. 1885, is Sunday, therefore the week numbers and month dates, of the first week are the same, as follows: November 1st, Sunday, 1st day of week. November 2d, Monday, 2d day of week. November 3d, Tuesday, 3d day of week. The "Key," Thursday, being the 5th day of the month, also the 5th day of the week, any other day or date is readily found as is always the case when Sunday is the first day of the month. Become familiar with May and August in Common Years, and May and October in Leap Years, for they are the most difficult except when the week numbers and month dates are the same in any of them. To find the 1st when the ''Key date' 7 is the 7th r take the next day, for whatever day of week has the 8th has also the 1st. Also if the "Key date"' is 5th or 6th it may be convenient to run forward to the 8th. or to the 9th for the 2d, in preference to going backward. In months of 30 days, the days which are 1st and 2d occur five times in that month. The 2d is always the last day of the month. The 3d is the 1st day of the following month. In months of 31 days, the days which are 1st, 2d, and 3d, occur five times in the month. The day having the 3d, always closes the month. The 4th has the 1st of the next month. In February, of common years, whatever day is 7th is also last, and the day that begins February begins 14 PERPETUAL MENTAL CALENDAR. also March and November. In Leap Years, the day that begins February also ends it. A little practice will enable you at a glance to see what date you must find the day of the week for, when 3^our given date is beyond the 7th, as follows: When any given dates for which you desire to find the day of the week are 8. 15, 22, 29 you see in an instant that you may find the day for the 1st, or if they are 9, 16, 23, 30, you find for the 2d. and so on. Therefore, dc not for- get that if you nan quickly find any day or date in the first week of any month you have substantially mastered all that is contained in the preceding pages. EXPLANATION NO. 4. HOW TO FIND THE " KEY " FOR AXY YEAR IN THE PAST OR FUTURE. Remember that the "Key" for any year is always the day which begins the year. The days of the week begin the years in an order that is perfectly systematic. The month dates of each month for different years pass from one day to another in the same systematic order. Let our own century — the 19th — be taken as a starting point in order to find the i; Key " for any year in other centuries. It may be regarded as a kind of "Century Key" for all other centuries. We find it most convenient to make special use of the Leap Years rather than common years. Unless there is strict care to distinguish between Leap Years and Common Years, there must be confu- sion and incorrect results. PERPETUAL MENTAL CALENDAL. 15 HOW TO DISTINGUISH LEAP YEARS. Since the beginning of the Christian Era, any year, the last two figures of which may be divided by 4 r without a remainder, is a Leap Year : or any year that ends with 0, 4, or 8, preceded by an even number, as- 1860, 1864, 1868, or that ends with 2, or 6, preceded by an odd number, as 1852, and 1856. Before Christ, 1, 5, 9, 13, 17, 21, etc., were Leap Years. The beginning of the iC Julian Calendar'* was about 45 B. C. THE ORIGIX OF OUR PRESENT CALENDAR, CALLED THE ; 'GREGORIAN. " In 1582 Pope Gregory XIII determined to reform the Calendar, as there was a difference of many days between the Solar and Civil years. He made the cor- rection by suppressing ten days. He called October 5th, (1582), October 15th. He then decreed that the Centesimal years should be counted as Leap Years, once in 400 years only; 1600 was reckoned as a Leap Year, and 2000, 2400, etc., will be; but 1700 and 1800 were not; and 1900, 2100, 2200, etc., will not be Leap Years. All the Centesimal years from 1600, A. D., back to 1 B. C, were Leap Years. It should be carefully noted that all Centesimal Years as 1700, 1800, etc., always end a century, instead of beginning one as many seem to think. The following table gives the unchanging order of the days of the week, as they become the "Key'' of the Leap Years in any century. The order must be memorized and made very familiar, which can be easily done by reciting backward the days of the week, each time omitting one dav. 16 PERPETUAL MENTAL CALENDAR . TABLE NO. III. ORDER OF DAYS. 1804, Sunday. 1808, Friday. 1812, Wednesday. 1816, Monday. 1820, Saturday. 1824. Thursday. 1828, Tuesday: 1832, Sunday. Take any number of Leap Years in any part of any century* and the above represents the exact order in which the days of the week begin the years. The table also represents the order of the days for every fourth year without any regard to the Leap Years, as 1809, Sunday. 1813, Friday. 1817, Wednesday. 1821. Monday, etc. but the order will be mostly used with Leap Years, in passing up and down in a century. PASSING FROM ONE CENTURY TO ANOTHER. The above ' ' Table " also gives the order of days in passing from one century to another, since October 15, 1582, New Style, as: 1604, Thursday, 1704, Tuesday,' 1804, Sunday, 1904, Friday. Each brace of four centuries after, is a duplicate of the above as 2004, Thursday; 2104, Tuesday, etc., etc. The first Leap Year of a century is always the 4th year, as 1704, 1804, etc. *The only exception to that is in the year 1582 the order of days is broken by the change in the Calendar which has already been named. PERPETUAL MENTAL CALENDAR. 17 Having found the "Key" for the first Leap Year, you can easily run the " Keys " of the Leap Years in that century in the order given in " Table No. 3," and whoever can do so has accomplished the most difficult thing to be done in finding any desired "Key." SOLAR CYCLE. Twenty-eight years make a Solar Cycle: in that time the same days have the same dates throughout the year, and only in that time as regards the Leap Years. EXCEPTION TO THE ABOVE. In passing out of one century into another in the regular order of years, prior to 1582, in 28 years the same days had the same dates and there was no break made by the centesimal years, for they were all Leap Years. Since 1600 the centesimal years have not been Leap Years, and instead of there being an interval of 28 years, in passing out of one century into another, the time is only 12 years with the two Leap Years closing a century, and 40 years with all the others. For Example. 1792, Sunday; 1796, Friday. In 12 years, which takes us into the next cen- tury, the same days again have the same dates, as 1804, Sunday ; 1808, Friday. But we find 1784, Thurs- day, 1788, Tuesday, and only in 40 years again do those days and others throughout the year have the same dates as 1824, Thursday, 1828, Tuesday. The same is true of all the others, and the same principle applies to any other two centuries in New Style, where the Centesimal year over which you pass is not a Leap Year. Sunday being the "Key" of the first Leap Year, (1804), in this century, after each interval of 28 18 PERPETCAL MENTAL CALENDAR. years, Sunday is again the "Key" of a Leap Year, as, 1804, 1832, 1860, 1888. The special use of those years, viz:, '4, '32, '60, '88, as reckoning points, will be of advantage in all centu- ries, for whatever is the "Key" of one is the "Key 1 ' of all, with the exception stated in foot note on page 16. 1st Example.— Find the "Key" of 1812. 1804. Sunday, (See Table Xo. 3. page 16) 1808, Friday. 1812, Wednesday. 2d Example.— Find the "Key" for 1844. 1832, Sunday. {Known Key.) 1836, Friday. 1840, Wednesday. 1844, Monday. 3d Example.— Find the "Key" for 1856. Knowing that 1860 has Sunday, we go back to 1856. Tuesday. 4th Example.— Find the "Key" for 1880. 1880. Thursday. 1884, Tuesday.' 1888, Sunday, (Known Key.) Beginning 1888, Sunday, and going back to 1880. RULE FOR FINDING THE "KEY*' FOR ANT LEAP YEAR. Begin with the "Key" of '4, '32, "60, or '88, which- ever of those years is nearest the desired year, and go forward or backward in the oi der of days given in "Table No. 3," page 16. ORDER OF DAYS FOR COMMON YEARS IN PASSING FROM ONE LEAP YEAR TO THE NEXT. TABLE NO. IV. 1804, (Leap Year) Sunday I 1809 Sunday 1805 Tuesday | 1810 Monday 1806 Wednesday I 1811 Tuesday 1807 Thursday 1812, (Leap Tear) . . . Wednesday 1808. (Leap Year) Friday I PERPETUAL MENTAL CALENDAR. 19 It is seen by the foregoing table that in going forward from a Leap Year one day must be passed over to find the "Key" of the first common year, then comes the regular order of the days of the week for four years, including the next Leap Year. In going backward from a Leap Year to common years, take the regular order of the days of the week backward for four years, including the Leap Year with which you begin. 1st Example.— Find the "Key" for 1833. 1832, Sunday. 1833, Tuesday. 2d Example.— Find the "Key'' for 1842. The nearest Leap Year is 1840. We find its "Key" and go forward to 1842, as follows : 1832, Sunday, (Known Kev. I 1836. Friday. 1840, Wednesday. 1841, Friday. 1842, Saturday. RULE FOR FINDING THE "KEY " OF ANY COMMON YEAR. Find the "Key" of the nearest Leap Year, and go forward or backward to the desired year. BF°By carefully examining the order of days for Leap Years in " Table No. 3," the method of going, forward or backward over Leap Tear "Keys" may be shortened for some cases, but it is not given as a new rule. It applies only where you desire to go forward or backward several years from some known '"Key" to some year the "Key" of which is not known. Long steps may be taken in such cases as follows: In going forward from any known "Key" For 12 years after, take the next day. For 16 years after, take the day before. For 20 years after, take the third day before. 20 PERPETUAL MENTAL CALENDAR. For example you want the "Keys" for 1872 and 1876. 1860, Sunday (Krown '"Key.'') 1872, Monday (12 years after.) 1876, Saturday (16 years after.) 1880, Thursday (20 years after.) In going backward from any known i; Key, 11 exactly reverse the above. Thus 1860 Sunday (Known "Key.") 1848 Saturday (12 years before) 1844 Monday (16 years before) 1840 Wednesday. ... (20 years before) EXPLANATION NO. 5. HOW TO FIND THE J ' KEY " FOPw ANY YEAR IN OTHER CENTURIES. It has been already shown on page 16 that the order of days is precisely the same in passing from one century to another since October 15, 1582, for each four centuries, for both Leap Years and Common Years, that is found with Leap Years in passing up and down in a century. For Example— 1604, Thursday. 1704. Tuesday! 1804. Sunday. 1904, Friday. Again. 2004, Thursday. 2104. Tuesday. 2204. Sunday. 2304. Friday. Hence we find that each brace of four centuries — beginning with 1601 — has precisely the same days and dates. Therefore if we have a '"Key." or any other PERPETUAL MENTAL CALENDAR. 21 day or date, it is the i; Key" day or date of the cor- responding year 400, 800, 1200, etc., years afterwards. Thus 1620, Wednesday is " Rev," 2020, Wednesday is "Key," 2420, Wednesday is '* Key.' 1 RULE FOR FINDING A ' ' KEY " OR ANT OTHER DAY AFTER OCTOBER 15, 1582, — NEW STYLE. Find the k ' Key," or the day of the corresponding year in the nineteenth century and pass to the desired " Key " or day of another century in the order given in ''Explanation No. 5" above, or in "Table No. 3." If any one should prefer it, the " Key'' of the first Leap Year may be found, and then pass up or down in the century the same as given heretofore for the nineteenth century. 1st Example.— Find the " Keys " for 1684, 1784, 1984- We know that the "Key" of 1884 is Tuesday. Hence we pass to the others required, thus: 1684 Saturday. 1784 Thursday. 1884 Tuesday. 1984 Sunday. 2d Example.— Find the ;t Keys" for 1685, 1785, 1985. 1685 Monday. 1785 Saturday. 1885 Thursday. 1985 Tuesday. In 1st Example above the years are Leap Years, in the 2d Example they are Common Years, but the order of days is exactly the same as in u Table No. 3." The order of days in passing from one century to another prior to October 5, 1582 — Old Style — differs from the order afterward, but is more simple. It is the exact order of the day* of the /reek. 22 PERPETUAL MENTAL CALENDAR. ORDER OF DATS IN PASSING FROM ONE CENTURY TO ANOTH- ER, "old style,' 1 beginning with 19th CENTURY, " NEW STYLE."' 1804, Sunday, 1504. Monday. 1404, Tuesday, 1304. Wednesday, 1204, Thursday, 1104, Friday, 1004, Saturday. 904, Sunday. It is seen by the above that it will be a very easy thing to find a " Key " or other day in a corresponding year in the 19th century and pass to any year of a century in "Old Style." Example.— Find the "Keys" of 1332, 1432, 1532. We know that the " Key " of 1832 is Sunday. Hence we find the others thus : 1832, Sunday. 1532, Monday, 1432, Tuesday. 1332, Wednesday. EXAMPLES FOR CORRECTION OF ERRORS, ETC. 1st Example: — Haydn's "Dictionary of Dates," page 89, says that " Black Easter Monday" was April 6, 1351. Find the day of week for April 6. 1851. The " Key" for 1852, (See Rule page 18) is Thursday, and the " Key" for 1851 is Wednesday. April 2, 1851, was Wednesday; (See "Table No. 1" page 6) hence April 6 was Sunday. April 6, 1851, Sunday, April 6, 1551, Monday, April 6, 1451, Tuesday, April 6, 1351, Wednesday, therefore " Black Monday " was April 4th. PPRPETUAL MENTAL CALENDAR. 2B 2d Example. — Ridpath's and Bryant's Histories of the U. S. say that Juan Ponce De Leon discovered Florida on Easter Sunday, March 27, 1512. Find the day for March 27,1812. The " Key" of 1812 is Wednesday. The first Wednesday in March, 1812, is the 4th, and the 6th, is Friday. W T hatever is the 6th is the 27th. (See page 9.) March 27, 1812, Friday, March 27, 1512, Saturday. Therefore if the year is correct, it was March 28th. The probability is that it was discovered on March 27, 1513, which was Sunday. (See Bancroft.) 3d Example. — Bryant's History of the U. S. says, Vol. II, page 266, that " On Sunday, the first day of October, (1664), FortCasiniir surrendered." Find the day for October 1, 1864. Friday is " Key ,r for 1864. The first Friday in October, 1864, is the 7th, (See Table No. 2 page 7) and the 1st is Saturday. October 1, 1864, Saturday, October 1, 1764, Monday, October 1, 1664, Wednesday. If it was "Old Style," then was October 1, 1664, Sat- urday, and October 1, 1665, was Sunday, for the days and dates of the 17th century, "Old Style," are identical throughtout with those of the 19th century, "New Style." (See Chart of " Keys.") 4th Example: — Dr. Whedon's Commentary (Vol. 3, N. T., page 225,) says, "The passover feast closed on April 3 (58) which appears to have been Tuesday ; and Paul started from Philippi, on Wednesday April 4. The five days to Troas would terminate Saturday, April 8." Which day and date are correct? The "Key for 58 is Sunday, same as 1758, New Style. (See "Key Chart"). 24 PERPETUAL MENTAL CALENDAR. April 2, 58, Sunday : April 3, Monday ; April 8, Sat- urday. Hence Saturday is correct, and Tuesday and Wednesday are not. Again it is said (page 230) that Paul landed at Tyre, "Monday, April 30'" (58). Whatever has the 2nd has the 30th. Therefore April 30, 58, was Sunday. 5th Example. — An excellent lady from New Eng- land insists that her wedding anniversary comes only once in four years. She is equally confident that she was married on Sunday. Time Feb. 29. 1836. "Key" for 1836, Friday. Feb. 5th was Friday and Monday was also 1st and 29th. Feb. 29, 1836, Monday. 6th Example. — Dec. 22d has been called "Fore- fathers" Day" because the "Pilgrim Fathers " landed on "Plymouth Rock," Dec. 11, 1620. O. S. Is Dec. 22d. "New Style.' 7 consistent with Dec. 11th. "Old Style," in 1620? Find the day for Dec. 11. 1620. O. S. The ''Keys" and dates of the 17th century. O. S.. are the same a^ the 19th century. N. S. "Key" for 1620, O. S., Saturday. First Date of Sat- urday in Dec, 1620, is the 2nd and the 4th is Monday, hence the 11th must be Monday. Dec. 11. 1620 O. S. Monday. Find the day for Dec. 22. 1620. N. S. "Key"" for 1620 N. S. Wednesday. First date of Wednesday in Dec, 1620, N. S. is the 2d. and the 1st is Tuesday, the 22d, must also be Tuesday. Dec. 22, 1620, N. S. Tuesday. The days of the week do not correspond. We find however that Dec. 21, 1620, N. S. is Monday. Hence we conclude that Daniel Webster should have deliv- ered his celebrated "Fore-fathers" Day" oration on Dec 21. 1820, instead of on Dec. 22d. PERPETUAL MENTAL CALENDAR. 25 7th Example. — M'Clintoek and Strong in their Cyclopaedia, Vol. 2, page 25, and Dr. De Puy in "People's Cyclopaedia,'' Vol. 1, under " Calendar/' tell us that Pope Gregory decreed that 1600 should not be reckoned as a Leap Year. They say, "begin- ning with 2000." Are they correct? If they are right and our "New Style" calen- dar from the present time back to 1600 has been cor- rect, then the "Key" of 1600 is Sunday, not Saturday as shown in the " Key Chart." Also the "Keys" for 1582 are Wednesday until October 5th, and Sunday after that date. In that case, Pope Gregory decreed that the change in the calendar should take place on Sunday. October 5th. The " Key " also for 1504, 1532 and 1560 must be Wednesday and not Monday, as shown also in the "Key" Chart." That would change every " Key " for every year from 1582 back to 45 B. C. The "Key Chart" as it now stands is in perfect harmony in the main with every reliable historical writer, so far as compared, who gives the day of the week in connection with his dates. TEST EXAMPLES OX THE SUPPOSITION THAT 1600 WAS XOT A LEAP YEAR. 1st. Whedon's Commentary (N. T. ) Vol. 3, pp. 225- 230. gives the following days and dates: Saturday, April 8, 58: Monday, April 17,58: Thursday, April 20. 58; Monday, April 24. 58: Wednesday, April 26, 58. If the "Key'" for 1560 be Wednesday, according to the order of days previously explained, the "Key" for 58 would be Tuesdav. 26 PERPETUAL MENTAL CALENDAR. April 2d being Tuesday, April 8th would be Mon- day (not Saturday), April 17th would be Wednesday (not Monday). April 20th would be Saturday (not Thursday), etc. If. however, Sunday is the "Key" of 58, as must be if 1600 is reckoned as a Leap Year, the above will harmonize. 2d. D'Aubigne says that Martin Luther was born on Monday, November 10th, 1483. If 1600 was a Com- mon Year, the -Key" of 1483 would be Friday. The first date of Friday would be the 5th. and Wednesday would be the 3d and 10th of November, and not Monday. If 1600 was a Leap Year, the " Key " of 1483 would be Wednesday. Hence if Wednesday was the 5th, Monday was the 3d and 10th. Let us suppose again that the days and dates as given by standard authors, prior to 1582, are in the main correct, and that 1600 was reckoned as a Common Year, then it must follow that days and dates as given by standard authors since 1582 "New Style," are in the main incorrect, and January 1st, 1885, should have been Wednesday instead of Thurs- day. The two periods certainly cannot be reconciled in their days and dates, as given by very many au- thors, except upon the basis that 1600 was a Leap Year. We therefore conclude that the Oyclopsedists, named above, are incorrect in saying that 2000 begins the Centesimal Leap Years since 1582, in accordance with the decree of Pope Gregory. PERPETUAL MENTAL CALENDAR. 27 TABLE SHOWING THE REGULAR INTERVALS OF ANY DAY IN BEGINNING A YEAR. 1804, Sunday, (Leap Year) 1809, Sunday, 5 years 1815, Sunday, 6 years }■ 28 Years. 1826, Sunday, 11 years | 1832, Sunday, (Leap Year) 6 years J 1837, Sunday, 5 years ] 1843, Sunday, 6 years j. 28 y 1854, Sunday, 11 years f 1860, Sunday, (Leap Year) 6 years j TABLE SHOWING THE REGULAR INTERVALS OF ANY DAY IN HAVING THE SAME DATE AFTER FEBRUARY, YEARS HAVING DIFFERENT "KEYS." 1455, November 10, Monday "j 1460, November 10, Monday, 5 years. 1466, November 10, Monday, 6 years. } 28 Years. 1477, November 10, Monday, 11 years. 1483, November 10, Monday, 6 years. J 1488, November 10, Monday, 5 years. ] 1494, November 10, Monday, 6 years. I 9ft Ymt , o 1505, November 10, Monday, 11 years. f zo lears * 1511, November 10, Monday, 6 years. J Melancthon tells us tbat Martin Luther's mother was very confident of remembering the day and the hour when Martin was born. That it was Monday, Nov. 10th, 11 p. m., but she was uncertain about the year. The family generally agreed that it was 1483. The "Key" for 1483 was Wednesday. The first date of Wednesday in November, 1483, was the 5th. Hence Monday was the 3d and 10th. ^O PERPETUAL MENTAL CALENDAR . If lie was not born in 1483, and yet the day and date were certainly Monday, November 10, then the year in which he was actually born could not possibly have been nearer than 1477 or 1488. So much of a blunder they would not likely make. It may be seen by the above " Table " that if at any time you have the day of the week and the month dale given, and you have lost the year, and know that it must be one of five years, you can readily find the year; or again, you may find it within a range of 6 or 11 years. The foregoing examples have been given to suggest the manner in which this Calendar may detect and often afford valuable aid in correcting errors in days and dates, and also in verifying the correctness of others. Whoever may learn it will be surprised at the numberless instances in which it may be used in ordi- nary business affairs, and especially in the reading of newspapers, magazines and books, embracing days and dates. CENTURIES HAVING THE SAME KEYS AND OTHER DAYS AND DATES. It may be of advantage to observe and remember that the "Keys" and other days and dates of the fol- lowing centuries, as grouped, are exactly the same. Hence, when you have a "Key" or other day or date in any one of the group, you have it in all those grouped with it. PERPETUAL MENTAL CALENDAR. 29 TABLE OF GROUPED CENTURIES HAVING THE SAME "KEYS*' OR DAYS AND DATES. 1601, New Style. I 1701. New Style. 501, Old Stvle. 1. Old Style. 1201, Old Style. I 701, Old Style. I 1101. Old Style. 1801. New Style. I 1901. New Style. 201. Old Stvle. I 401, Old Stvle. 901 i Old Style. I 1101. Old Style. 1601, Old Style. \ Oct. 15. 1582. to 1600 N.S. 301, Old Stvle. j 101, Old Style. 1001, Old Style. | 801. Old Style. 1701. Old Style, I 1501. Old Style. To Sept, 3d." 1752. Old Style. | 45, B. C. Old Stvle. 601. Old Stvle. 1301, Old Style. In the above, if you have a "Key" or other day or date in the century beginning with 1801. you have it also for the corresponding year or time in the centu- ries beginning with 201. 901, 1601, O. S. If you there- fore desire a day or date in the century beginning with 1, as in 4th example, page 23, where the "Key" for 58 is desired, find the "Key" for 185S and then quickly pass to 1758, according to the order of days previously explained, and you have the "Key" for 58. Or you may find it in 1858 and that gives the "Key" for 258 and from that year can easily pass to 58. In the practical use of this Calendar, different per- sons will have suggested to them various ways of abbreviating and thereby expediting the mental work. 30 PERPETUAL MENTAL CALENDAR. AMERICAN REVOLUTIONARY BATTLES, ETC., ON SUNDAY. It has been sometimes stated that battles that were fought, or that were begun, on Sunday, usually went against the party that brought on the engagement. Those who wish to do so, may study the following and ascertain whether it has been true in our own country. Quebec, Dec. 31, 1775, "Key" Sunday Boston (British fled), March 17, 1776, "Key" ..Monday Fort Mifflin, Nov. 16, 1777, "Key" Wednesday Monmouth, June 28, 1778. "Key" Thursday Kettle Creek (Ga,), Feb. 14, 1779. "Key" Friday Stono Ferry, June 20, 1779. "Key" Friday Chemung (Indians;, Aug. 29. 1779. "Key" Friday Rocky Mount, July 30, 1780. "Key" . . * Saturday Hanging Rock, Aug. 6, 1780, "Key" Saturday LAST WAR WITH ENGLAND. Detroit (Surrendered) Aug. 16, 1812 Pimartains Town Oct. 18, 1812 Elizabethtown Feb. 7, 1813 Burlington Heights June, 6, 1813 Hampton June 13, 1813 Black Rock July 11, 1813 Fort Niagara Dec. 19, 1813 Horse Shoe Bend March 27, 1814 Fort Erie ■-■-... July 3, 1814 Plattsburg Sept. 11, 1814 Rodriguez's Canal (New Orleans) Jan. 1, 1815 New Orleans Jan. 8-13, 1815 AMERICAN CIVIL WAR. Bull Run July 21, 1861 Mill Spring Jan. 19, 1862 Fort Donelson Feb. 16, 1862 PERPETUAL MENTAL CALENDAR. 31 Hampton Roads March 9, 1862 Pittsburg Landing April 6-7, 1862 Winchester (Ya.) May 25, 1862 Cross Keys and Port Republic June 8-9, 1862 South Mountain Sept. 14, 1862 Prairie Grove (Ark.) Dec. 7, 1862 Chickasaw Bayou Dec. 27-29, 1863 Arkansas Post Jan. 11, 1863 Big Black (Miss.) May 17, 1863 Port Fisher (N. C.) Dec. 25, 1864 Port Pisher Captured Jan. 15, 1865 Hatcher's Run Feb. 5, 1865 Petersburg (Va.) April 2, 1865 , Sal 3 n J Tllr 1? Weil - s I'lmr v:;]V'ri' Illll'Mial Table of Leap Year "Key Days" from 45 B. C. to A. DJ.752 "Old Style," and from A. D. 1582, to A. D; 2000 "New Style." 101 Fri .)' Sat Mon Sat linn rue e-i-i Mon Thill- |! ! s',"; |";'-: Wed Mon !;;: Vi-i Mon '.;"; I'll'' Silt. ,.,u, .,,„: B03 s ~ - .,;: Fri Wed KVJII Hat Thur :;■>: :;:■;,; Fri :,(, Mon ;■•■• Thur Tue Mill i-v! IK -.-■ id ;•-.:.! ah,' Tm- ,,-.,. Sun Ill IV Mil Thur (10! aii3 Sat 904 S,M, DOS Fri Wed an a- riuu •!•: Tun 08V » Fri !)4I a.,- MAI Tin' i)R| ai: Fri Wed avi DH Sim Fri urn Weil ^Unil 160.,|\Vim1 IliOIThiir !, England corrected its Calendar by suppressing 11 days. September 3, dar by suppressing was called 10 days. October 5, 14. Wednesday was "Key" for was called Oct. 15. Monday was " 1752 up to September 3. Key" for 1582 up to Oct. Saturday \ . Friday > LIBRARY OF CONGRESS 022 008 895 9 •