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31 Problem 32. There are many ecret ways by which Atronomers may date their letters to each other, ome of them as follow. ☉ ♍ 5° 51'—if you receive a letter from your friend in the country thus dated, you look in the Nautical Almanac, and correct the Sun's motion the day in which it is in that ign and degree, and find it was on the 29th of August, at midnight, in which he wrote it.—Again, ♄ 13° 10' ♍—This answers to September 22, at ix in the afternoon——Again, the Dragon's Head in ♓︎ 8° 8', this will direct you to the 7th November, at noon—or, ☽︎ ♋︎ 2° 17'—☿ 8$s$ 2° 12' this can be no other time than Decem. 10th, at noon; and many other ways you may invent from thee examples, according to your fancy.

Problem 33. To find the Jewih hours by the Planisphere, viz. they divide the day, and night, be it long or hort, into twelve equal parts, from Sun-riing to Sun setting, for the day, and from Sun-etting to its riing for the night; thus, in the Equinoctial, the Jewih hours, and the common hours are alike in length, viz. 60 minutes; but, it is evident, when the Sun is in Cancer, the twelfth part of the day will be more than 60 minutes, and the night hours les, and they continually vary between the Tropics: thus, uppose at London the longet day is 16 hours, 26 minutes—multiply this by 60, and divide the product 986m by 12, and the quotient is 82m$2/12$ for the length of a Jewih hour by day under Cancer, and this is the length of the night hours under Capricorn; by this rule, we find a night hour under Cancer is 37 minutes,