Address of Sir William Thompson. 283 
tivation by the labors of many able investigators within the last 
n years. 
To prodigious and wearing toil of Kirchhoff himself, and of 
owe la 
mgs of the British Association is well illustrated by the fact 
that it was through conversation with Pliicker at the Newcastle 
substance gives a continuous spectrum—that an in 
gas under varied pressure gives bright bars across the contin- 
e sharp, hard and fast 
be spectrum, some of which, from th 
