MARYLAND GEOLOGICAL SURVEY 515

where I is the longitude west of Greenwich, expressed in degrees and
decimals of a degree.

(b) If the tabular quantity thus corrected is greater than 12h., sub-
tract 12h. from the tabular quantity and add one day to the date in
the margin. If the tabular time is less than 12h. it will be p. m.
time; if greater than 12h., a. m.

It will be noticed that for the tabular year two eastern elongations
occur on January 10 and two western elongations on July 10; there
are also two culminations on April 10 and on October 10. The lower
culmination either follows or precedes the upper culmination by
11h. 58.1m.

TABLE XVI.'
Azimuth of Polaris when at elongation f or any year between 1897 and 1910.

	Lat.	1897.0	1898.0	1899.0	1900.0	1901.0	1902.0	1903.0	1904.0	1905.0	1906.0	1907.0	1908.0	1909.0	1910.0
	+37	o / 1 33.3	o / 1 32.9	0 / 1 32.5	1 32.1	1 31.7	1 31.3	1 30.9	1 30.5	1 30.1	1 29.7	1 29.3	1 29.0	1 28.6	1 28.2
	38	1 34.5	1 34.1	1 33.7	1 33.3	1 33.0	1 32.6	1 32.2	1 31.8	1 31.4	1 31.0	1 30.6	1 30.2	1 29.8	1 29.4
	39	1 35.9	1 35.5	1 35. 1	1 34.7	1 34.3	1 33.9	1 33. 5	1 33.1	1 32.7	1 32.3	1 31.8	1 31.4	1 31.0	1 30.6
	40	1 37.3	1 36.8	1 36.4	1 36.0	1 35.6	1 35.2	1 34.8	1 34.4	1 34.0	1 33.6	1 33.2	1 32.8	1 32.4	1 32.0

Mr. Schott states that " the deduced tabular azimuth (counted from
the north) may generally be depended upon with no greater error than
±0'.2. The table was computed with the mean decimation of Polaris
for each year; a closer result will be had by applying to the tabular
values, the following correction, which depends on the difference of
the mean and the apparent place of the star:

	For Middle of	Correction.	For Middle of	Correction.
	January, .	. . —0.4	July, . . .	+0.3
	February,	. . —0.3	August, . .	+0.1
	March, . .	. . —0.2	September, .	—0.1
	April, . .	. . 0.0	October, . .	—0.3
	May, . .	. . +0.2	November, .	—0.6
	June, . .	. . +0.3	December, .	—0.8

¹ Extracted from C. and G. S. Report, 1891, App. 1, or Bull. No. 14.