188 
NATURE 
[| APRIL 25, 1912 
facts and processes, two-fifths to the applications 
of photography, including photo-mechanical 
methods, while the remaining fifth is devoted to 
the action of light, the correctness of photo- 
graphs, perspective, &c., with a final chapter on 
“Photography as a subject to be taught in art and 
industrial schools.” In this last chapter Dr. Vogel 
makes an earnest plea for the inclusion of photo- 
graphy in the courses of study of technical institu- 
tions, not “to train professional photographers... 
but so far as it is of importance for art and science.” 
He bases his plea, not only on the opinions of 
others, but also on his nine years’ experience as 
professor of photography in the Royal Industrial 
Academy of Berlin. 
This is the book that Mr. Garrett has sought to 
modernise, or “bring up to date,” as the saying 
is. The present author has given the volume a 
new title, transferred Vogel’s name from the title- 
page to the preface, and states that “although the 
present book is of necessity practically a new 
work, it is based upon the lines laid down in the 
original publication.”” The only noteworthy omis- 
sion of the substance of the original volume that 
we observe is the last chapter, that is the plea for 
the consideration of photography as a subject to 
be included in the curriculum of colleges, because 
of the importance and the universality of its 
applications. Perhaps the author is justified, for, 
in this country at least, there is little “advance ” 
to record with regard to this matter. The study 
of photography, even by those who need its aid, 
too often means no more than working from the 
instructions issued by manufacturers, with per- 
haps an occasional question across the dealer’s 
counter. 
The remainder of the volume is rearranged 
somewhat and added to. The chief additions are 
on gelatino-bromide dry plates (which, of course, 
were not in use when Vogel wrote), photography 
in natural colours, Réntgen-ray photography, 
photo-telegraphy, and animated photography. 
These final chapters are interesting, instructive, 
and well illustrated, though they sometimes 
wander rather far from photography, as, for ex- 
ample, in the consideration of the apparatus used 
in R6ntgen ray work. When a matter such as 
this is treated and illustrated so fully, we natur- 
ally expect that the more purely photographic 
subjects will have received at least as much atten- 
tion, but here we are disappointed. Within the 
space of four pages there is all that we can find 
with regard to carbon printing, the gum bichro- 
mate process, ozobrome (ozotype is not men- 
tioned), printing-out papers, toning and fixing, 
phosphate papers, bromide printing, gas-light 
papers, and platinum printing ! 
NO. 2217, VOL. 89] 
Lenses are classified into (1) rapid rectilinears, 
| (2) portrait lenses, (3) wide angle lenses, and, as 
a kind of supplement, telephoto lenses. All that 
we can find about Abbé and Schott, and the optical 
work they carried out which has revolutionised 
the construction of photographic lenses, is that 
when they “undertook to construct a lens suit- 
able for this work,” that is, exact work, “they 
had the very great advantage of having a definite 
aim in view.” 
The author’s style is generally clear, but there 
are some sentences which_need a little expansion 
or explanation, because as they stand they are 
liable to mislead the reader. For example, at p- 
323 we are told that 
“the superiority of apochromatic lenses in micro- 
photographic work is only very apparent when the 
preparation to be photographed is unstained, 
and extremely minute details are required such as 
can only be resolved with light of short wave- 
length. Hence it is that the cheaper achromatic 
lenses are much more frequently used in conjunc- 
tion with stained preparations, autochrome plates, 
or orthochromatic plates and colour screens.” 
The unqualified statement that it is “essential ’” 
to have a stand of “a large type and provided 
with a rotating and centering stage” for the pur- 
poses of photomicrography, appears to us to be 
contrary to general experience. When such 
matters as these are elucidated, the volume will 
be an interesting and useful treatise, though it 
can scarcely claim to be comprehensive. 
Cue 
THE GRAMMAR OF SCIENCE. 
The Grammar of Science. By Prof. Karl Pearson, 
F.R.S. Part i., Physical. Third edition, re- 
vised and enlarged. Pp. xx+394. (London : 
A@vand C! Black, ronr)eerice ‘6s. nets 
HE notices formerly given of the first and 
second editions of Prof. Pearson’s well- 
written ‘Grammar of Science” (see NATURE, 
vol. 46, pp. 97-99, 1892, and vol. 62, pp. 49-50, 
1900) scarcely need to be added to in the way of a 
general review. The main feature of the new 
edition which differentiates it from the others is 
the addition of two new chapters: chapter v., on 
contingency and correlation, and chapter x., 
modern physical ideas. The former chapter is 
particularly noteworthy, presenting as it does in 
a wonderfully small compass the scientific signifi- 
cance of the two terms contingency and correla- 
tion. The general reader, whose mathematical 
symbolism is of the most elementary type, will 
probably find difficulty in appreciating the fulk 
scope of this chapter. A simple concrete example 
might not have proved amiss. 
