METALLIC WIRES BY ELECTRICITY. 445 
the two thermometers, the dimensions of which are given in 
Poggendorff’s Annalen, vol. xliil. p. 49, and vol. Ixiii. p. 485, and 
furnished them with different platina wires, the radii of which 
varied from 0:058 to 0°116 line, and the length from 60 to 97 
lines, according as it was found necessary. In experiments which 
were to be compared directly with each other, the thermometer 
remained unchanged. 
Incandescence depending on the Power of Discharge. 
At some distance from the thermometer a platina wire was 
inserted in the connecting circuit, and the balls of the ther- 
mometer protected by screens from any external influence. A 
certain number of battery jars were charged with an increasing 
quantity of electricity, until a discharge was attained, producing 
visible incandescence in the wire by daylight, and each time the 
temperature of the thermometer was observed. This method of 
procedure was continued with different numbers of jars. The 
following series of observations show the discharges which suf- 
ficed to produce incandescence, and the attendant rise in the 
thermometer. 
Experiment 9.— 
Number Quantity Increase of temperature 
of jars. of electricity. in thermometer. 
5 12 20°9 
ove 20°0 
3 10 
2 8 20°3 
3 10 21°6 
4 1l 21°8 
5 12 20°2 
eee 20°7 
Experiment 10.—A new platina wire gave the following :— 
Number Quantity Increase of temperature 
of jars. of electricity. in thermometer. 
2 8 20°7 
7 14 20°4 
2 8 20°2 
see 20°7 
Experiment 11.—With a third platina wire, incandescence 
was observed attending the following discharges :— 
