on a Permanent Electric Current. tr 
p = proportion of above current which passes through the Thom- 
son galvanometer. 
7 = total resistance of circuit containing Thomson galvanometer 
uring main experiment. 
The above formula reduces to the form 
h 
460 sin — tana d'H 
Mov ee 
ee iP 
tdprtan Osin= 
to the Thomson galvanometer, a matter of considerable ease. 
The following pages give some details of the study of the 
various metals examined. 
GoLp. 
ae. 
the ratio a This value, however, would be very much 
larger than that obtained when thicker strips of metal are used, 
and facts to be hereafter mentioned make it appear quite prob- 
able that the thickness of the strip, as above arrived at, is sev- 
eral times smaller than the true thickness.* 
Without attempting therefore any accurate determination of 
the constant of this first strip (A), I pass on to 
Gold Leaf, Plate (B). 
This plate also is of very thin metal, and in general I shall 
use the term gold leaf, when speaking of the metal in this 
shape, and use the term gold /oi/ to denote the strips of con- 
siderable thickness. 
ns See also Albert v. Ettingshausen, ‘ Bestimmung der Absoluten Geschwindig- 
keit,” ete. Sitzungsberichte Akad. Wien, vol. lxxxi, p. 446, 1880. He found the 
value of the thickness indicated by the weight in similar cases, to be from four to 
ten times as great as that indicated by the resistance. 
