May 2, 1912] 
NATURE 
215 
the suspicion would be quite unfounded, and the 
author is merely putting an easily avoidable 
obstacle in the way of a general acceptance of 
his treatise by responsible engineers. 
Mendelism. By Prof. R. C. Punnett. Third 
edition. Pp. xiv+176. (London: Macmillan 
and Co., Ltd., 1911.) Price 5s. net. 
Att who knew Prof. Punnett’s little book entitled 
** Mendelism ”’ in its original form will welcome 
the greatly amplified edition of it which he has 
now published. This edition has been entirely re- 
written, and is illustrated by five coloured plates. 
Prof. Punnett’s book, in its original form, did 
so much to familiarise the public with Mendelian 
phenomena and hypotheses that the present work 
requires no recommendation from ‘‘the old 
shuffling bribed sots, called Reviewers,’’ to use 
the words of William Cobbett. 
The book is especially valuable because it is, 
in the words of the author, ‘‘in some measure 
a record of the work accomplished by the Cam- 
bridge School of Genetics.” If the book were 
a complete record (which, of course, it is not), 
the work of that school would be an achievement 
of which a larger group of investigators working 
over a longer period of time might well be proud. 
The theories which have been put forward to 
explain the new facts may or may not survive 
the test of future experiment and criticism; they 
may be nearer the truth than the more cautious 
of us dare to hope. But whether they survive 
these tests or not, the new facts discovered con- 
stitute a solid advance in human knowledge which 
the carpings of those who criticise the theories 
put forward to explain these new facts cannot 
rob of one iota of its value. 
The attempt to answer the question how far 
the Mendelian theory as held by Prof. Punnett 
approximates to the true explanation (if we may 
make the extravagant assumption that there can 
be such a thing) is a fascinating exercise for those 
who are more interested in the relation 
between the human mind and the so-called objec- 
tive world than in the objective world itself. 
But this is neither the time nor the place to discuss 
the truth of the Mendelian hypothesis. It is 
enough, for the present, that the Cambridge 
School of Genetics has contributed handsomely 
to the capital of our knowledge of hereditary 
phenomena, and that the book before us is an 
admirable presentation of these contributions. 
Boiler Draught. By H. Keay Pratt. Pp. vii+ 
138. (London: Constable and Co., Ltd., 
1911.) Price 4s. net. 
In this little book the author has endeavoured 
to assist those to whom the efficient working ot 
steam plant is of importance by explanations of 
methods of determining whether existing arrange- 
ments are satisfactory. The book opens with a 
number of elementary calculations regarding the 
pressure, volume, weight, and temperature of air, 
and the resistance to flow. Calculations in rela- 
tion to chimney, forced, and induced. draught 
NO. 2218, VoL. 89] 
, follow. 
There are also sections dealing with the 
construction of chimneys, the applications of 
mechanical draught for land and marine purposes, 
and the chemistry of combustion. The treatment 
of the subject is designed to suit those practical 
men whose knowledge of mathematics and. 
science may be scanty. Indeed, the author states 
in his preface that while mathematical investiga- 
tion is well appreciated, the results are likely to 
be greatly misleading if relied on too completely 
to the exclusion of practical experience. ‘‘ It is 
for this reason that men of high scientific attain- 
ments are sometimes at fault when they have 
to tackle a problem in practical work.’’ 
That there may be another side to this question 
is also rendered very clear in the book. Thus in 
chapter vi. are given methods of calculating the 
approximate over-all dimensions of a fan. The 
methods employed can give rough results only, 
yet we find data stated to five significant figures 
and worked into the calculations, including one 
case of the weight of a cubic foot of water taken 
as 62°418 lb. While many valuable results and 
suggestions occur here and there, obtained from 
the author’s practical experience, there is very 
little reference to recent experimental work, such 
as that conducted at the Manchester School of 
Technology and elsewhere. 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
this or any other part of NaturE. No notice is 
taken of anonymous communications. ] 
Burdon Sanderson and Vitalism. 
In his interesting and sympathetic notice, in 
Nature of March 21, of the Memoir of Burdon 
Sanderson, your reviewer discusses Burdon Sander- 
son’s attitude towards ‘“‘vitalism,’ and thinks that 
the editors of the Memoir (my sister and myself) 
have scarcely represented this attitude satisfactorily. 
Our task in this connection was a somewhat difficult 
one, and we may have failed in it; but the grounds 
of the difficulty are of so much general scientific 
interest that it may perhaps be worth while to refer 
to them more fully. We quoted in the Memoir from 
the following letter, written by Burdon Sanderson 
from Algiers in 1904 to Miss Florence Buchanan, 
D.Sc. (who was then assisting him), with reference 
to a general paper which he was endeavouring, in 
the face of ill-health, to prepare on the general results 
of his electro-physiological work. 
“From your pencil notes on my MS. I take it 
that you regard as the result of an investigation of 
the excitatory process the complex of data relating 
to localisation, time-relations, and intensity of elec- 
trical change—all of these being measurements. To 
me it appears that when you have got by measure- 
ment a complete knowledge of what happens elec- 
trically (intensity, localisation, and _ time-relations), 
this knowledge, however exact it may be, is of no 
value unless it enables you to conjecture the nature 
of the excitatory process of which these phenomena 
are the concomitants. 
“The excitatory process can best be defined as a 
sudden transition from less functional activity (the 
