Tuesday, November 15, 2011

nov. 15, 1811 (fri.)

In October, Melatiah Nash, a teacher, librarian, and grocer in New York, wrote concerning a book he is writing, to be called The Columbian Ephemeris and Astronomical Diary. The work is to be a sort of combination of a common and a nautical almanac, as well as a simple introductory textbook of astronomy.

This morning Mr. Jefferson replied, giving his encouragement and some advice, including a method by which readers in places other than where the book is published can calculate their own local time of sunrise "with scarcely more trouble than taking it from an Almanac" --
"add the Log. tangent of the [sun's] declination:
taking 10, from the Index, the remainder is the Sine of an arch which, turned into time and added to VI. Hours
gives Sunrise for the Winter half
and Sunset for the Summer half of the year."

2011 note: There appears to be no free, publicly-accessible, online copy of The Columbian Ephemeris and Astronomical Diary, for the Year 1812, but several university libraries have a print copy.

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