452 RIESS ON THE INCANDESCENCE OF 
Indication of thermo- 
Metal composing Radius meter at the time 
the wire. in lines. of incandescence. Mean. 
Exp. 23. Copper . . 0:0253 615 63°4 
63°0 61:0 : 
62°7 59°8 
60°7 
602 Cr ee ced 
we 2a. Pinta cc hte | Uae 10°9 
11°4 
i Se aes 1 4 
0°03879 57°0 
56°66 
~ 95. Brass... ). ‘O'O2261 21°2 
22°2 
21:2 
210 co) wets) ee eee 
To get rid of the influence of the different thickness of the 
wire, we must, according to page 450, divide each indication of 
the thermometer by the fourth power of the radius of its cor- 
responding wire. We thus obtain values for the amount of heat 
produced in a thermometer interposed in the connecting circuit, 
and relative values for the power of the current of discharge 
necessary to produce incandescence in wires of equal thickness 
composed of different metals 
From the mean numbers deduced from the experiments, the 
following series of metals, arranged according to the increased 
power of the current, is obtained, in which the current of dis- 
charge required by platina is taken as unity, 
Incandescence appears in with the power of the current 
i 
Tri) Soe le wh a etetea es bee eee 
German Silver. <> ..- «cd. a, 1s 2 OFDSD 
Platina” — ses i saceek tie ee 
Palladium. 3./2)ec.s a<tiee Bese 
Lig: cl Pee Meee Ta ee PE UT 
BOUVET co. . -.60<c aR Meee oat eS 
0 eee oy een a 
By the assistance of this table, if the incandescence of a wire 
be observed, with the attendant thermometrical indication, we 
are enabled to calculate the indication of the thermometer for 
