1872.] Notices of Books. 247 
well-attested facts, of equal intrinsic probability, or reject all. I 
cannot believe in Cretaceous fossils as realities, and reject Silu- 
rian as freaks of nature; neither can I accept the facts B. may 
have witnessed, and reject those of the rest of the alphabet. 
Yet if all the main classes of facts are admitted, the spiritual 
theory appears as clearly a deduction from them as the theory of 
extinct animals follows from the facts presented by their fossil 
remains. ‘The position of the Quarterly Reviewer is, that there 
are no facts worth speaking of, and, therefore, no true spiritual 
theory can be founded on them. This is safe ground, as long as 
all the evidence for the facts is carefully denied, misrepresented, 
or ignored. But when there are ten thousand witnesses to these 
facts, of whom say nine thousand are as good and competent as 
A. or B., it is not safe ground for A. or B. to admit just so much 
of the facts as they have witnessed themselves, and reject the 
rest. The problem we have now to solve is—how much of the 
facts are true. ‘Till this is done by some better test than indivi- 
dual experience, it is premature to discuss what theories may or 
may not explainthem. In the meantime, let no one prejudge 
the question till they have studied Mr. Owen’s facts and carefully 
weighed his arguments. 
ALFRED R. WALLACE. 
Spectrum Analysis in tts Application to Terrestrial Substances 
and the Physical Constitution of the Heavenly Bodies. 
Familiarly explained by Dr. H. ScHELLEN. Translated 
from the Second Edition by JANE and CaroLine LassELt. 
Edited, with Notes, by W. Huaains, LL.D., D.C.L., F.R.S. 
Tue first edition of this work, though a valuable contribution to 
the literature of Spectroscopy, was not free from defects, and, 
although published so late as 1870, it failed to give as complete 
an account as could be wished of some of the more remarkable 
applications of spectroscopic analysis. The present edition (we 
refer for the moment to the German editions) has been carefully 
revised, and several of the sections have been enlarged and en- 
riched, more particularly those which relate to observations of 
the sun. The work thus forms a sufficiently complete and tole- 
rably exact synopsis, as well of the phenomena of spectrum 
analysis as of the methods by which they have been applied to 
the interpretration of some of the most recondite problems of 
nature. 
Such a work well merited translation into English, and those 
students of spectroscopic analysis in England and America who 
do not read German owe thanks to the Misses Lassell for under- 
taking the labour of translation, and to Dr. Huggins for editing 
and annotating this excellent treatise. 
The work is divided into three parts. The first deals with the 
artificial sources of high degrees of heat and light; the second, 
