68 Sir George Shuckburgh’s Account 
about six times as large. Each circle was divided into 360*, 
and those again into three or four subdivisions, and being 
furnished (it may be supposed) with moveable sights, the 
observer was enabled to take the elevation or depression of 
any object above or be'ow the ecliptic, together with its dis- 
tance from the meridian, or colure, that circle being previ- 
ously placed parallel to its corresponding one in the heavens. 
The first measure would give the latitude of any heavenly 
body, and the latter the longitude. This instrument, or 
something similar to it, seems to have been in use as early as 
the time of Hipparchus, who lived in the second century 
before our Saviour, (vide Weidleri Hist. Astron. p. 319; et 
Tychonis Brahe Mechanic a ) and was continued to be used 
by astronomers for upwards of fifteen centuries afterwards. 
(2.) The next account that occurs is by J. Muller, Re- 
giomontanus, sive Joannes de Monte Regio, who flou- 
rished about A. D. 1460, and, in a posthumous treatise ex- 
pressly on this subject, intitled Scripta clarissimi Matbema - 
tici M. Joannis Regiomontani de Torqueto, Astrolabio 
armillari , Reguld magnd Ptolemaica, Baculoque Astronomico, 
&c. &c. in quarto, printed at Nuremberg in 1544, has 
given a pretty full account, not only of the armillary as- 
trolabe, but also of the torquetum, which in fact was no- 
thing more than a portable equatorial, and may be consi- 
dered as the first instrument truly of this kind. As this trea- 
tise is become extremely scarce, and I know of only one 
copy in this kingdom, I take this opportunity of apprizing 
the curious, that it is to be met with in the British Museum. 
A short description, however, of the torquetum, with a pi ate 
©f the instrument, will be found in Mons. Bailly's Astro - 
