C ] 
ment of a true Sphere, barely by turning round the 
Wheels which if fo, the Confequences will be, 
if}, That all Grinders of fuch Glades, <&c. will 
gladly ufe them 5 a labouring Man, whom they hire 
for lefs Wages, being, by the Help of this Machine, 
able to do more Work in a Day, than a skilful Arti- 
ficer, without it, in Two Days. And, 
2 dly, All Gentlemen will have the Pleafure to 
know the Lenfes they make ufe of are truly fpherical, 
it being impoffible this Machine fhould produce any 
other Figure. 
If you think this Contrivance of Importance 
enough to be offered to the Royal Society, your 
will do me a great deal of Honour to communicate 
it from, 
Explanation of Fig. r. Tab. I. 
A. A Globe covered with Cement , in which are 
fixed the Pieces of Glafis to be ground . 
This Globe is faftened to the Axis , and turns 
with 
B. the Wheel B. 
C. Is the brafis Cup , which polishes the Glafis: This 
is faftened to the Axis , and turns with 
D. the Wheel D. So that the Motion of this Cup 
C is at Right Angles with the Motion of the 
SIR 
Effex- Court, 
Nov. 29. 1737. 
Tour moft obliged 
Humble Servant , 
\ Samuel Jenkins^ 
Globe A, 
II. Ob- 
