of the Equatorial Instrument . 71 
to measure the angular distances between the stars, having 
no divided circle at right angles to the polar axis, to take 
right ascensions, cannot come into the class of equatorial 
instruments. Nor need I here mention Mr. Molyneux's te- 
lescopic dial, ( Sciothericum telescopicum , in 1686 ) though 
depending upon the principle of a polar axis, which, like a 
ring dial, or equinoxial dial, was little more than a play-thing 
for an amateur in astronomy. 
(8.) But about the year 1730 or 1735, when the practice 
of astronomy had assumed a new face in this kingdom, under 
the skill of Dr. Halley and of Dr. Bradley, Mr. Graham 
invented his sector, for taking differences of right ascension 
and declination out of the meridian ; and this may be consi- 
dered as bearing a considerable affinity to the equatorial in- 
strument in principle, and differing from it only in the ex- 
tent of its powers. Of this instrument, which is well known 
to every practised astronomer, a complete account will be 
found in Smith's Optics, Vol. II. § 885. and in Mr. Vince's 
Astronomy. I approach now to the period when the modern 
equatorial instrument, properly so called, took its origin. 
(9.) Mr. James Short, a person of very considerable emi- 
nence for his skill in the theory and practice of optics, and 
particularly for the unexampled excellence to which he had 
carried catoptric telescopes, in which, I believe, he has never 
yet been exceeded : Mr. Short, I say, probably finding him- 
self capable of making telescopes, of very moderate dimen- 
sions, fit for many astronomical purposes, and able to exhibit 
several of the heavenly bodies by daylight, provided they 
were furnished with a convenient apparatus and movement 
for that purpose, applied a two feet reflecting telescope, for 
