He 
or 
=r 
Rays emitted by Glowing Platinum. 
Seale-divisions. Readings. Mean. 90°—a. Intensity. 
25 °9 
l4 26.°7 26 °33 9 56 0 02976 
26 °4 
24 °0 
15 23 °3 23 °8T 7 28 12 "01696 
24 °3 
24 -0 
16 23 °5 23 °83 7:25 48 “01600 
24 -0 
17 Ne aes AG ee 
18 
19 os ae pe cast 
rom the 17th division onward the intensities were too 
small to allow of further measurements. 
he other readings in the above experiment were as follows: 
Before. 
Leucoscope-rea' BOR se il ee iy ke 40°°6 40°°3 
Opthalmometer-readings (for the hot wire, .--. ---------------- 56°°5 
Leucosco preninee Se oo ee ee cee ts ee 40°°5 40°°4 
Opthalmometer-readings (for the hot wire)... ..--------------- 6 5 5 
ometer-readings (for the cold wire)_-------- -- 99°-4 «=«.29°5 =~ 29°" 
Movement of the galvanometer during the experiment* - -------- = 
= 0: Wilh 0 Oe rere Pe oe ae ee 90°*1 ©. 
TABLE 
Region 8 on Kirchhoff’s Scale 609°1. 
2 Temp. (°), Observed. Calc. 
0-2: 
13583 9 0-026 +015 | 17596 0623 0°623 -000 
1264 60-020 «= 9-087 «= 4-007 | 190LT «= 4ak aT + 008 
16395 9193 «= 0-145 = 008 | 19327 1760 1959 +7001 
16185 = 9-988 3=— 0-257 = +037 
* 
of An Movement of the spot of light over 1-25 meters corresponded to a change 
de: mperature in the wire sufficient to be detected by the leucoscope. 4°™ 
+ Dra @ negligible decrease in temperature. See : 
’ Per (Philosophical Magazine, xxx, 345) gives 525° U. as the point of 
tempera ible rays begin to r. Granting the accuracy of this 
oS Tement, we tind a long interval of at least 600° within which the intensity lhe 
far the red rays is ex dingly small compared to their intensity at 1900°, So 
8 as the present method i urably small : 
