450 E. L. Nichols—Character and Intensity of the 
glowing platinum wire w, upon the lower half of the slit 
The rays of the other wire, w,, after total reflection in the 
prism p,, passage through the convex lens J, and a second 
total reflection in the small prism » form a similar image 
ocular Nicol, reach the eye in form of two spectra, lying side 
I = 06s" a, (3) 
where ais the angle between the planes of polarization of the 
Nicols. : 
it was made fast, and not moved again during the whole = 
of the Investigations, These positions, according to the mea 
Taser I 
Lines, Scale-divisions, - Lines. Scale-divisions. 
A 135 b 12°84 
ee 8-05 F 14°63 
0 8°74 G 19°03 
D 9-96 Ht 23°28 
E 12-37 : Peas 
: sss IIl. * 
: The accurate determination of the temperature of a gloves ee 
platinum wire, presents serious difficulties. Repeated ae 
