[ 52 ° ] 
wilh’d, that the obfervation fhould be made princi- 
pally in thofe places, the longitude of which is known, 
with the utmoti: exadtnefs potiible, from other obfer- 
vations ; which would ferve the better to determine 
the parallax of the Sun by the comparifon of thofe 
obfervations with fuch, as fhall be made in the Eaft 
Indies. We already have a confiderable number of 
obfervations relating to the longitude of Cambridge 
and New York, betides the new ones, which may be 
ft ill made there ; fo that thofe two places would be 
the molt proper to obferve the approaching trantit of 
Mercury over the Sun ; which I detire you to recom- 
mend to the Royal Society, in order that they may 
exert all their intereti: to procure fuch obfervations. 
I am, with perfect efteem, 
S I R, 
Your moft humble, and 
moll obedient fervant, 
De I/Ifle. 
Defcription of a Piece of Mechanifn contrived 
by James Fergufon ,for exhibiting theTime y 
Duration 3 and Quantity , of Solar Eclipfes y 
in all Places of the Earth . 
Read Feb. 
1 7 54 * 
2i, r | A HE principal Parts of this ma- 
chine (See Plate XIX.) are, 
i. A terreftrial globe turned round, by a handle. 
Oil 
