544 



REPOET — 1888. 



rigidly held and bored out, some even being afterwards scraped to a 

 bearing. It was, however, fonnd that there was no necessity for such, 

 refinement, as after a very brief period coils simply made by twistino- a 





□□ 



J 



FIC.3 



taper rod round a turned cylinder found their own bearing, and were 

 quite as effective as those which had been bored out. 



'Relation between force and resistance. — Of the coils exhibited, those 

 lettered a, i, c, and d had sections corresponding to those similarly 

 lettered in Fig. 3. These four coils have been experimented upon by 

 means of the apparatus shown in Fig. 4. On the face-plate of a lathe 

 were fixed cylinders upon which the coils fitting loosely were successively 



;^N 



A 



placed. The head h of the coil C was prevented from revolving by means 

 of a lever L having a fulcrum at F attached to the lathe bed B. The 

 lever L is counterweighted by means of a scale-pan W hanging over a 



