180 FE. H. Hall—New Action of Magnetism 
Length as weighed = 5°68 cm. 
Width sa cae | ae 
Area including projections es. 4:15,..% 
i on 98 grm. 
Thickness (taking sp. gr. = 7°79) = 00347 cm.* 
With this plate the following results were obtained : 
2 Vt 
M. C. ie ae 
Apr. 29th, 6680 k X tan 38° 37’ et x 10° 
“cc cc ce cc 49° aM 
Mean = aa. Xx 10° 
PLATINUM. 
One strip of this metal has been used. 
Length as weighed = 6°32 cm. 
Width 2-016 
Area including projections oo 1. *, , 8G: 
Wei ht = °457 grm. 
“Thickness (taking sp. gr.=22°1)= -00274 cm. 
With this strip only one series of observations was made and 
that was rather a hasty one; I found 
MxvV 
M. C. R’ 
Apr. 28th, 6830 k X tan 66° 2’ 417 * 10”° 
NICKEL. 
There was some difficulty in obtaining a strip of this metal 
of proper shape for the experiment. The piece used was ob- 
tained by stripping off the nickel plating from a piece of ee 
upon which the deposit had been purposely laid in such a m 
ner as to make it easy to remove. The strip thus obtained ak 
narrow and irregular in shape and its thickness cannot readily 
being, next to iron and cobalt, the most baohaly magnetic sub- 
stance. As already stated, this direction was found to big i 
* The plates of very thin rolled iron used were furnished me by 
land, who is hee for a sepey of the same to the courtesy of beat 5 Poe 
of Allegheny Observ: 
+ It is evident that ‘the ‘values of this ratio thus obtained for iron are to so 
gre eat advan ntage of Riggers: easily determinable. Nickel has hardly been examine 
quantitatively as big , and platinum is not sufficiently magnetic to present any 
difficulty of this s 
