ADDRESS OF PROFESSOR LOVERING. 627 
side to the other, during the last fifty years. The irresolvability 
of many of the nebule, by powerful telescopes, led Herschel to 
espouse the cause of a diffuse primeval matter, out of which 
worlds were fashioned. No wonder that, in particular cases, the 
hegative evidence was sometimes turned into positive evidence on 
the other side, by improvements in telescopes. Although every 
nebula which deserted from the nebular hypothesis strengthened 
the suspicion that the remaining irresolvability was purely optical, 
4 sufficient amount of negative evidence would probably have 
always existed to create more than a doubt in the minds of many 
astronomers. On the discovery of spectrum analysis, observers 
ied around it, in the hope of finding an escape from the 
dilemma: and this new hope has not been disappointed. The 
continuous spectra of some nebulae prove them to be suns, envel- 
oped in more or less of atmosphere. The broken spectra of other 
nebulæ show that they are in the condition of an incandescent 
gas. The classification which the spectroscope makes of the neb- 
ule Corresponds so well with their telescopic appearance as to 
justify the confidence which one class of astronomers had in their 
way of deciding on the truth of the nebular hypothesis. While 
“Ne spectroscope has manifested varieties of material, color, tem- 
perature, and consolidation in nebule and stars, both single and 
composite, beyond anything which the perfected telescope’ could 
ever have revealed, it has at the same time found enough of earth 
aK of them to make man feel at home any where in the visible 
universe, The fact that certain well-known substances on this 
Pass current everywhere in nature leads irresistibly to the 
„asion that all the specimens came originally from the same 
. = It is the legitimate office of science to reduce the more 
__. Pex to the simple: to explain, if possible, the existing state 
of matter by an anterior state. The nebular hypothesis, which 
- Attempts to do this, no longer starts from a conjecture but a 
reality : viz., the existence of diffused incandescent vapor; and 
Science will hold on to it, until a better theory of mechanical 
“evelopment is found.— Concluded in next number. 
