[ 4II ] 
right angles to each other, exprefs a horary circle, and 
a parallel of the equator (the telefcope moving in the 
plane of the equator) j and ferve to flaew the fituation 
of the fpots in general. The other is an oblique 
wire, the correfponding one having been taken out a 
few days before, in order to leave the field more 
clear. 
As to my latitude, I have tried it different 
ways with fuch inftruments as I have; but what I 
trufled to mod, were the zenith difiiances I took of 
Cephei and « Cygni at one time } and and ^ 
Urfe Majoris at another (for fome nights . fuccef- 
fively) with my tranfit telefcope ; from which I 
fufpend a plummet, at a certain diftance from the 
quadrant underneath, one of whofe radii becomes 
thereby a tangent; which being graduated, I cal- 
culate by it the diftance of ftars near the zenith, 
and corredl the errors of collimation by taking 
them both ways. I have like wife taken ftars both 
ways, with my equal altitude quadrant, which in- 
deed is a very imperfect inftrument for that purpofe : 
but, by calculating the mean, it turns out much the 
fame as by the other method, viz. 52° 40' 20'' 
north. 
The other figure (2) is a fketch of my tranfit-te- 
lefcope, which you enquired after. The principle 
it goes upon is th;s : the center of the objedl-glafs 
remains immoveable, while the telefcope (by crofs- 
axes at right angles to each other, which interied at 
that center) hangs as it were from thence, and has a 
free motion every way; and particularly its motion 
eaft and weft is freed, as much as pofllble, f om 
fridion. At the focus, where the crofs wires are, ' 
G g g 2 it 
