Improvement in the Quadrant of Altitude, 5 
thicknefs that the circles require to give them folidity, in con- 
tradiftin&ion to mathematical planes ; unlefs a part of a qua- 
drant was cut out next the vertex to give them clearance : by 
th is means the arch being lifted up from the fpindle, and put 
on the other fide of the brafs meridian for the afternoon, it 
will then come within io° or 15 0 of the meridian; and if the 
the of this fpace fhould be wanted, it can be fupplied by 
reverting the timilar operation for the morning; and the back 
fide of the upper end of the quadrant at U being champered, 
or bevilled off, this will admit it to come as near to the meri- 
dian as I have mentioned. 
The fteel fpindle is eafily adjufted to the zenith ; for the 
globe being rectified to its latitude , fet the brafs carriage at 
liberty, bring the quadrant and meridian together, face to 
face, and Aide the carriage, till the lower extremity of the 
quadrant huts upon the horizon, and there ferew it faff 
It is, however, to be noted, that I have found fomething 
neceffary by way of holdfaji , to prevent the brafs meridian from 
(Lifting its latitude, and that without confining it in any other 
refpe£l. — What 1 have found to anfwer this purpofe is repre- 
fented, fig. 3. The crutch-like piece of wood ABC is (hewn 
as feen looking right down upon it. The circle DE is the hori- 
zontal fe£tion of the fouth pillar of the globe. The ftrong wire 
pin FG, that goes through the two arms of the crutch and pillar, 
lerves as an axis upon which its other extremity at JB is at free 
liberty to lift up and down, but without lhake upon the pin ; 
and the whole being fplit with a fine faw, from B to H, the notch 
BKi lays hold of the under fide of the brafs meridian, and by 
tightening the finger ferew LM, it firmly clips it, and retains 
it in any given polition. And that it may be under no confine- 
ment croJs-ways r the hole in the pillar is opened on both tides, 
* -v ■ as 
