PERPETUAL CALENDAR. An arrangement for ascertaining the day of the week ing to any desired date, and for solving other similar problems. The following form of per-. petual calendar was arranged by Capt. J. schel, and is probably the best yet devised. As bere given, it covers the period from 1798 to 1950, but it ('t1 11 be extended easily in either Every (late is composed of four elements, viz.: (1) Day of the week.
(2) Day of the month.
(3) Name of the month.
(4) Number of the year.
Any three of these ele ments being given, we can find the fourth from the perpetual calendar. Thus, suppose we wish to find what (lay of the week cor responded to Slarch 4, 18115, on which (Illy Lineoln was inaugurated President of the United States for the second time. Entering the calendar in the column headed `March.' and opposite the 'day of the month' 4, we find the sign +. Now, en
tering the column contain ing the year ISO, and go ing up it to the same sign we find opposite that sign, on the right, the 'day of the week' Saturday. Ac cordingly, Lincoln was in augurated on a Saturday.
Again, suppose it is re quired to find in what years March 4 (inauguration day) can fall on a Sun day. As before, for March 4 we find the sign +. Opposite Sunday we find that sign in the first column of years, beginning with 179S. 1804. etc. In all the years in this column, therefore, March 4 will fall on a Sunday. But Presidential in augurations usually occur only in years follow ing leap years, which latter are indicated by italics in the perpetual calendar. Consequently, Sunday inaugurations occurred in 1849, 1377, and will occur in 1917, 1945.