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POPULAR SCIENCE REVIEW. 
extreme credulity. When a Fellow of the Royal Geological Society of 
Ireland proceeds to discuss a geological question, and combines Croll’s 
hypothesis and the acceptance of revelation- visions, we feel for the scientific 
body to which he belongs. 
THE STUDY OF INSECTS.* 
W E have already given a notice of Dr. Packard’s excellent treatise on 
General Entomology {Popular Science Review, January). Since that 
notice was written, the fifth part has been issued, and we hasten to say 
a word or two about its contents. Part V. is fully equal in every respect to 
those which preceded it, both in illustration and typography. It continues 
the account of the Lepidoptera, but does not quite complete it. The de- 
scriptions are, as before, clear and terse, and the woodcuts, many of them 
original, are numerous and good. As might be supposed, the Bomhycidce 
occupy a considerable portion of the part ; but other families, as Spliingidce, 
Rapilionides, Noctualitw, and Phalcenidce, receive due consideration. We 
must repeat our commendation of this excellent treatise. 
DISINFECTANTS.t 
D r. ANGUS SMITH here reprints, with some additions, his report made 
to the Cattle Plague Commissioners. He has dealt with the whole 
subject of deodorisers and disinfectants on broad and scientific grounds j but 
he has hardly given us anything new, and he has not gone into the 
rationale of the action of these substances as thoroughly as is desirable. 
Still his volume will be very useful as a practical handbook and as a work 
of reference, and we think he did well to rescue his observations from the 
oblivion to which all ^^Blue books ” are consigned. 
LARDNER’S OPTICS. J 
rj HE student who desires to study physics in these days has really an 
-F “ embarrassment of riches ” in tlie abundance of manuals from which he 
may clioose a text-book. Some years since Lardner’s handbooks were much 
thought of; but tlic old editions are now beliind tlie age, and therefore the 
♦ (Juidc to tlie Study of Insects.” P>y A. S. Packard, Jun., M.D. 
Part V. Salem, U.S., 1801). 
t “Disinfectants and Disinfection.” Dy Robert Angus Smith, Ph.D., 
F.K.S., etc. lOdin burgh : Edmonston and Douglas, 1860. 
X “ Handbook of Natural I’liilosophy.” Dy Dionysius Lardner, D.C.L. 
“Optics.” Edited by T. Olver Harding, D.A. London: Walton, 1869. 
