ASTRONOMICAL CALCULATIONS. (Prepared by S. Hart Wright, M. D., A. M., Ph. D., Penn Yan, N. Y.) Five eclipses for 1902, as follows: I. Partial of the sun, April 8, of less than one digit, seen only in the Arctic Ocean. IL Total of the moon, April 22, seen in Asia, Europe and Africa. III. Partial of the sun, May 7, of about ten digits, seen in New-Zealand and in part of the Pacific Ocean. No. 1, first contact. No. 2, first six digits. No. 3, total and middle. No. 4, last six digits. No. 5, last contact. N is north point of the moon. No. 1 is 86° east; No. 5, 118° west of it. Note-The line from the moon's centre to N points to the North Star always. Mercury, Feb. 1 to 3 and Sept. 25 to 30. after sunset; also March 11 to 15 and Nov. 4 to 7, rising before the sun. Venus, Jan. 5 and March 21. Mars, not this year. Jupiter, Aug. 5. Saturn, July 17. Uranus, June 10. Neptune, Dec. 24. Jupiter will be in Capricornus after March 16. Saturr will be in Sagittarius all the year, and Uranus in Scorpio all the year. ERAS. The Mahometan year 1320 begins April 10. NOTE. The times of the lunar eclipse of October 16-17, the moon's phases and the tides for three ports are given in Standard Time, used by railroads, and the tides the standard used at the ports is that for the 75th meridian. For all other computations in the Almanac true mean solar time is used. Standard time, being artificial, cannot be used for such without much confusion and some error, besides being very impracticable where solar time is needed. AZIMUTH TABLE OF POLARIS, OR NORTH STAR, 1902. The surveyor may find the true north by observing Polaris either when it crosses the meridian or is at the greatest eastern or western elongation. The latter plan is preferable to the former, but it calls for a knowledge of the azimuth of the star, which is not uniform for all seasons and latitudes. Hence the table given herewith. If one knows approximately the time when the elongation will be reached, he can follow the star with his transit until it ceases to move further to the eastward (or westward). Then, by reading his compass and applying the correction for azimuth, he will get the variation of the needle. In case of doubt it may be wise to repeat the observation a night or two later. The eastern elongation is the one to use from early May to the middle of October, and the western will serve for all but a few weeks of the remainder of the year. In 1902 Polaris will be at its eastern elongation on May 10, at about 4:17 a. m.; May 16, 3:54 a. m.; June 1, 2:51 a. m.; June 16, 1:52 a. m.; July 1, 12:54 a. m.; July 16, 11:55 eve.; August 1, 10:52 p. m.; August 16, 9:54 p. m.; September 1, 8:51 p. m.; September 16, 7:52 p. m.; October 1, 6:53 p. m.; October 16, 5:50 p. m. The western elongation occurs on October 16, at about 5:40 a. m.; November 1, 4:37 a. m.; November 16, 3:38 a. m.; December 1, 2:39 a. m.; December 16, 1:40 a. m.; January 1, 12:36 morn.; January 16, 11:36 eve.; February 1 10:32 p. m.; February 15, 9:34 p. m.; March 1, 8:43 p. m.; March 16, 7:44 p. m.; April 1, 6:40 p. m. The event occurs four minutes earlier each night than on the preceding one. From the closing days of March until May 10 Polaris will be on the meridian, and hence in the true north, when a plumb line will cover it and 38 Cassiopeæ simultaneously. The latter is a star of the sixth inagnitude, some 20 degrees distant from the Pole Star. Delta Cassiopeæ, some 10 degrees further away, but brighter, is approximately in the same celestial longtitude, but 38 Cassiopeæ corresponds much more precisely. It will be directly under Polaris on April 1, at about 12:47 a. m.; April 16, 11:49 p. m.; May 1, 10:49 p. m., and May 10, 10:14 p. m. AZIMUTH OF POLARIS (NORTH STAR) FOR 1902, WHEN AT ITS GREATEST ELONGATION, EAST OR WEST, FOR THE LATITUDE AND DATES GIVEN. January 11 12 3411 22 57 1 24 40 1 26 32 1 28 35 1 30 52 1 33 2311 36 91 39 14 1 42 38 January 51 January 21 February 1 February 11 March 51 43 51 18 59 ... April .....(21) May 1 May 21 1 13 2 July 1 July .... July 24667764 August 11 29 11 81 August Septemb'r. 1 Septemb'r 21 50 311 12 18 1 22 40 1 24 21 1 26 13 1 28 16 1 30 32 1 33 2 1 35 48 1 38 521 42 15 |