' f 5” ] 
After you have polifhed your glafs about ten ml- 
- nutes, you again grind your pollfher upon the convex 
tool with emery, as before, for fear the pitch has, by 
working, loft any of its proper figure^ and the oftener 
you do this, the truer will be the figure of your 
glafs j and in this manner you proceed till the glafs is 
quite polifiied. 
You then take your glafs off its handle, by holding 
it before the fire, till it is fo warm that you can Aide 
the handle off the glafs ; and whilft the glafs is warm, 
you take off as much of the pitch as you can with 
the fharp edge of a knife ; you then lay the glafs 
down to cool, and, when quite cold, you drop fome 
fpirits of wine upon it 5 and this, with a cloth, will 
wipe off the reft of the pitch. 
You then examine the center of the furfaces of 
your glafs j and if it lies to one fide of the center of 
your glafs, mark that place with a fpot of ink, and 
then put on your handle as before, upon the fide that 
is now polifhed, with its center over the fpot of ink, 
and grind your glafs as before, till the circular re- 
maining part of the glafs to be ground is as much 
diftant from the center of the glafs on the other fide 
from the fpot as the fpot was from the center of your 
glafs; you then by heat return your handle to the 
center of the glafs, and proceed to grind and polifh 
this fide of the glafs as before. 
N. B. The concave and convex tools fbould be 
ground with fine emery, after you have done one fide 
of your glafs ; for the oftener thefe are ground to- 
gether, you will be the more fure of having your 
figure true. 
