Pty ie see RTE Pe eee eee eee TL Se ae 
spectrum of a flint prism, I came upon 
cold band whose deviation indicated a (probably) very great 
AMERICAN JOURNAL OF SCIENCE. 
[THIRD SERIES.] 
ArT. XXII.—Experimental Determination of Wave-Lengths in 
the Invisible Prismatic Spectrum; by S. P. LANGLEY. (With 
late V.) 
Note.—The following investigation was made at the expense of the Bache 
fund and is published here by the permission of its trustees. It is the subject of 
a still unpublished memoir presented in April, 1883, to the National Academy 
ences, in whose Transactions the unabridged communication will be found. 
In September, 1881, while engaged upon Mt. Whitney, in 
measuring with a linear bolometer the heat in the invisible 
pon a hitherto unknown 
spectrum. 
The amount of energy in any region of the spectrum, such 
as that in any color, or between any two specified limits, is a 
* Since desi as “2.” 
Am, Jour. ee Series, Vou. XXVII, No. 159.—Marcu, 1884. 
4 
