H. Draper—Diffraction Spectrum Photography. 407 
@ to H, is marked by the presence of bolder groups of lines, 
and most conspicuous are those between 3820-3860, 3705-8760, 
s strikingly shown in the enlarged phen I am not as 
ele 
and could not be comprised in a memoir of this length. 
have also tried to utilize the photographic spectra of the late 
Prof, Wi As Miller, published in the Transactions of the Royal 
Society for 1862, but for some reason, probably insufficient 
manner that is both necessary and attainable. The diffraction 
3% tra of metalline vapors that I have made are not yet ready 
use, 
eg probabilities are that each of these groups will be found 
Thi due to several elements, as is plainly seen 1n the group H. 
'S compound line, which is commonly spoken of as being 
“aused by calcium, iron and aluminum, is in reality much more 
