m 
MINUTES OF PROCEEDINGS OF 
Series C. — A gun-metal cylinder 8 ins. in diameter, and revolving 
at 1625 revolutions per minute, was substituted for the iron 
cylinder. 
Experiment No. 1.— No. % phosphor-bronze. No sparks. 
Experiment No. 2.— No. 7 phosphor-bronze. No sparks. 
Experiment No. 3.— No. 8 phosphor-bronze. No sparks. 
Experiment No. 4.— Gun-metal ingot. No sparks. 
Experiment No. 5.— Copper sheet. No sparks. 
Experiment No. 6.— Wrought-iron. No sparks. 
Experiment No. 7.— Steel. No sparks. 
