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[[top right corner]] 138 [[/top right corner]] [[left margin]] Essay towards finding the Longitude at Sea. [[/left margin]] 1. [[superscript]] st [[\superscript]] Let it be granted, that by the help of the Sun, or Stars, the precise time of the day, or night, may be known, whereever a ship may be, with sufficient exactness. 2. [[superscript]] d [[\superscript]] As at present, every system of navigation contains a table of the Sun's declination, for every mid-day, calculated for the first meridian, for a certain number of years to come; that is to say, the sun's place, or rather the earth's place in the ecliptic, is pointed out for every mid-day. Therefore it will be readily granted we hope, that a table may be [[strikethrough]] found [[/strikethrough]] formed, containing the meridian that will be in the Zenith of [[underlined]] London, [[/underlined]] for every mid-day, every hour, and second of time, for any desired time to come. These things being premised, let the mariner be provided with such a table; and with another table, containing the right anscension, declination, and celestial longitude, of all such fixed stars, as are easily observable by the naked eye. Then every sailor may know at once (his latitude, and) what meridian is in his zenith, every time he observes the culmination of any known star; elevated at least, thirty-five degrees above the horizon, which he may do, by the help of a good quadrant; or by finding the difference, between the magnetic and true meridian. It is taken for granted that he knows the time of its culmination, with sufficient exactness. And it is certain, that the longitude sought, must be, the distance between the meridian in his zenith, at the time of observation, and the meridian in the zenith of [[underline]] London [[/underline]], at the same time of the same day, and what that distance is, he finds, with one glance on his tables. The author conceals his real name, under the fictitious one of WICMW BRITANNICUS. P.S. It is hoped, proper judges will allow this plan to have its foundation laid in truth, and in that case, the following considerations will naturally recommend it, [[underlined]] viz. [[/underlined]] That no Time keeper is necessary to discover how that time passes, at the first meridian; neither is a marine chair necessary in taking observations of heavenly objects, easily perceivable by the naked eye; and when neither sun, [[strikethrough]] moon [[/strikethrough]] moon, Jupiter, nor Mercury can be seen, observations in abundance may be had from some or other of the numerous tribe of fixed stars, whose place in the heavens change not, as that of all the planets do. Gents. Mag. Nov. 1767. p. 540. [[left margin]] The Descent or fall of Water in Rivers. [[/left margin]] "The ingenious Mr. Smeaton, in a report delivered last year to the trustees for improving the navigation of the river Lee, observes, that the descent or fall of that river, during a course of more than thirty-one miles, is one hundred and evleven feet, or something less than one mile in 1760." Monthly Review Nov. 1767. p. 370.
Transcription Notes:
The word "evleven" is the word she uses and is not a typo error.