408 H. Draper—Diffraction Spectrum Photography. 
complex, for there can readily be counted in it more than fifty 
lines in the original negative, and a careful inspection of the 
accompanying paper picture shows a large proportion of them. 
This observation leads us toa more general statement. The 
exact composition of even a part of the spectrum of a metal will 
Le 4 
to 
? 
Bierstadt to state, that without his personal supervision, such 
sharp and fine-grained proofs could not have been obtained, 
and that no other printing-press process that I know of could 
4 this work at all. As an illustration of 
the difficulty of depicting the relative intensity of lines, we 
may examine 3998, which in Angstrém’s chart is shown sed 
and instead of being single, is triple, as is well seen the 
enlarged spectrum. erage 
hen, however, we compare Angstrém’s chart with Pe 
tion of the surprising accuracy of the Swedish philosopher. 
‘< v h prisma- 
iV~ 
many more. 
be 
_ In the earlier part of this memoir, it was stated that the sei 
tive intensities of the lines in the spectrum were correctly TeP 
