Blake on the Teeth of Cog-Wheels. 89 
mark here that it is by no means intended that all the 
curves which are included under this name are adapted to 
practical purposes, for even the epicycloidal curves are not 
so.— But it is not improbable that further investigations 
may show that some of them are better adapted to mechan- 
ical purposes than any of the epicycloidal curves. 
tis another great desideratum in wheel work that the 
teeth should act without friction.—But this point, though 
€ 
guage.* propose to show in a few remarks, under the 
significant of their common property. They will therefore 
treated of under the head Araipsic curves, where the 
general principle which embraces all possible curves of this 
sort, will be given; together with the means of determining 
cha , Q% We $+ r a © £. 
t This remark is intended to t pp 0 Hing re 
Made up of straight lines parallel to the axis of the wheel. It is not true o: 
the spiral or Helicoid teeth, invented a few years since in France, and now 
ith great success i branches of mect in tk 
gre: 
Von. VI.—No. 1. 12 
