402 
POPULAK SCIENCE EEYIEW. 
the book proves a most interesting one ; the records are, in most instances, 
up to date — though in a few this is not so — and in general are well selected^ 
Moreover, the work is well got up, and printed, considering its American 
origin, in very good clear type. We fancy the editor does not receive the 
Monthly Microscopical Journal,” as he records Dr. Hudson’s discovery of 
Pedalion mira as being a novelty taken from another journal ; whereas, as 
histological readers are aware, this very singular and interesting rotifer was 
described nearly a year earlier by Dr. Hudson in a communication to the 
‘^Monthly Microscopical Journal.” We observe also that in.the Report of the 
Royal Commission on Scientific Education, the critic confounds the secretary 
with the members. Withal, the book is interesting and instructive, and we 
wish it every success. 
TYNDALL’S AMERICAN LECTURES.* 
P ROFESSOR TYNDALL is certainly the Helmholtz of England, if not 
something better still. We have often had to give him what might 
appear, to those ignorant of the man, unseemly praise, but which we felt 
we were thoroughly honest in awarding. And often all our encomiums 'were 
modest indeed when contrasted with those ebullitions of kttdos which ^our 
American brethren have very recently indulged in. Dr. Tyndall has seemed 
to electrify them, and we do not wonder at their tendering him the highest 
praise, for now in the work before us we can see the reason of it all. Here 
is a book which gives the words in which the English lecturer indulged, and 
we cannot wonder that the various audiences which he addressed were well- 
nigh enrapturecl with their speaker. For assuredly it would be impossible 
to find within our language a work in which more eloquent word^are em- 
ployed to detail more striking facts, and withal are addressed to an audience 
essentially unscientific it its character, and which can yet appreciate, jta 
a very intense degree, the wonders and the beauty of the principles set 
forth. 
We know of no work in the whole range of natural philosophy which 
deals with its subject in such clear and incisive words as the present one ; 
and furthermore we find in it the difficulties of optics explained in a fashion 
which for clearness and intelligbility stands unrivalled. We may point to- 
one or two portions of the work, in which the style is singularly lucid. And 
in the first place we may take that portion in which its author seeks to- 
explain, to a popular audience, the exact nature of diffraction. This is 
an exceedingly difficult matter to make people comprehend, but we think 
Dr. Tyndall has happily succeeded in making it understood. We can- 
not follow him in his explanation, for it would take us too far and would 
occupy too much space ) and therefore we leave it for the reader himself. 
But what, for instance, could be simpler than the passage in which Dr. 
Tyndall explains the error of the mighty Newton. ^‘Newton,” he says. 
* Six Lectures on Light,” delivered in America in 1872-1873. By John 
Tyndall, LL.D., F.R.S., Professor of Natural Philosophy in the Royal 
Institution. London: Longmans, 1873. 
