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[ 327 attempted to deduce this quantity from the theory of

gravity, it (timid feem that the earth performs its annual revolution round the fun at a greater dillance than is generally imagined a lince Mr. Profeffor Stewart has determined the fun's parallax to be only 6 ', 9, and Mr. Mayer, the late celebrated Protector at Gottingen, who hash brought the lunar tables to a degree of perkaion almoll unexpeaed, is of opinion that it cannot exceed 8" In this uncertainty, the allronomers of the prefent age are peculiarly fortunate in being able fo Coon to have recourfe to another tranlit of Yentas in r769, when, on account of that planet's north latitude, a difference in the total duration may conveniently be obferved, greater than could pallibly be obtained, or

WM men expefted by Dr. Halley, from the lad tranlit.

The experience which we gained in the year 1761, the knowledge of the errors, from whatever

mule they may mile, which mull unavoidably be committed in oblervations of this kind, will enable us to put in praetice every method of baying this problem, and to determine with what degree of accuracy, and within what limits, the true quantity of she fun's parallax may be obtained, and confequently the dimenlions of the whole folar fyftem. But, before-I proceed to give a computation of the

effea of parallax at the feveral places where this tranfat oughtto be obferved,it will be necellity to premite the principles upon which the general calculus was SI, Machin, Profdtoe of Afironomy at Grahlm College, met entetled G raviry, p. 24.

deduced the ,:me queogoty many ream ago. See

ins Lsn,

Um:a Mmim moranag


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