of the Equatorial Instrument. 75 
In 1771 Mr. Nairne published an account of his equatorial 
telescope, in the Philosophical Transactions for that year; and 
in 1772 or 1773 Messrs. P. and J. Dollond printed an account 
of theirs. Each of these instruments were furnished with coun- 
terpoises, and, in general principles, were at least similar, if 
not the same. The preference that I was inclined to give at 
that time to my own instrument, made by Mr. Rams den, 
was owing to the peculiar advantage of a swinging level, to 
the unexampled accuracy of its divisions, and its great porta- 
bility. If, in what I have just now said of the three last in- 
struments, I should have committed any error with respect to 
the priority of their improvements, I must leave that point 
to be settled by the artists themselves, and shall hasten to the 
description of the instrument I set out with. But first one 
word with respect to an instrument that has been in frequent 
use on the continent, called, very absurdly, a Parallactic Ma- 
chine. 
(11.) The first notice, that I find of it, is in the History of 
the Academy of Sciences at Paris, for 1721, p. 18, in a me- 
moir of Mr. Cassini, with a description and plate of it ; also 
in the History of the same Academy for 174b, p. 121, wherein 
it is said to have been proposed by Mr. Passement, but 
without any description of it ; it will, however, be found 
described, with a plate of it, in the Dictionnaire de Mathema - 
tique, par Mr. Saverien, two vols. quarto, 1753 ; and this ac- 
count has been copied into Owen's Dictionary of Arts and 
Sciences, in four vols. octavo. It appears to have been a 
frame of wood supporting a polar axis, with an equatorial 
and declination circle, of only a few inches in diameter ; and 
was in fact no more than a very bad stand to a refracting, 
L 
MDCCXCIII. 
