OcTOBER 26, 1916] 
NATURE 
147 
PHYSICS. 
(1) A Student’s Heat. By I. B. Hart. Pp. vii+ 
376. (London and Toronto: J. M. Dent and 
Sons, Ltd., 1916.) Price 4s. 6d. 
{2) Elementos de Fisica Descritiva para a 4° ¢ 
5° Classes dos Liceus. Por. Dr. F. J. Sousa 
Gomes e Alvaro R. Machado. 5° edicdo, 
revista por Alvaro R. Machado. © Pp. 528. 
(Braga: Livraria Escolar de Cruz y Ca., 1915.) 
HART?’S text-book of heat is intended’ 
(1) M R: 
for use in the higher forms of secondary 
schools, for advanced students in technical col- 
leges, and for those taking a pass degree exam- 
ination at the university. The author has included 
in his book descriptions of many modern methods 
of determining thermal constants and results of 
recent experimental investigations. Although the 
calculus is introduced in the section on thermo- 
dynamics, a knowledge of elementary algebra 
and geometry will suffice for the perusal of the 
greater part of the book. The text is furnished 
with a large number of clearly drawn diagrams, 
but the exposition in some parts is open to con- 
siderable criticism. 
In the paragraphs dealing with electrical 
methods of measuring temperature the author 
assumes his reader to have no knowledge of elec- 
_ tricity, and explains the chief points of the simple 
electric circuit with the aid of a diagram showing 
cell, ammeter, resistance, and voltmeter all con- 
nected in series. In connection with the platinum 
resistance thermometer, the compensating leads 
are not made of copper, nor is it usual to stan- 
dardise the instrument in the way described by 
the author. The variation of resistance with tem- 
perature is represented by R;=R, (1+ at+ i’). 
According to the author, B is neglected for approx- 
imate measurements, and a@=0'00366; while for 
more accurate work the constants a and B are 
determined by measuring the resistance at 0° (ey 
roo° C., amd —273° C. At the last-mentioned 
temperature the resistance of a pure metal is known 
to be zero. Again, when describing the thermo- 
couple method of measuring temperature, on p24; 
we have “the difference in temperature at the junc- 
tions induces an electromotive force, and the gal- 
_vanometer registers a kick.”” The formula derived 
for the expansion of a liquid by the weight ther- 
mometer method, on p. 49, is wrong. On p. 86, 
dealing with molecular velocity and temperature of 
a perfect gas, it should be made clear that it is the 
Square root of the mean square velocity of the 
molecules which is proportional to the absolute 
temperature and not their mean velocity. It is 
difficult to see how Charles’s law for unsaturated 
vapours is verified by the experiment described on 
P. 131, since the vapour will be subjected to vary- 
ing pressures. On p. 182 we have the statement 
that Newton’s law of cooling is an approximation 
to Stefan’s law. This is wholly erroneous, since | 
the law of Stefan refers to loss of heat by radia- 
tion alone. Each chapter is furnished with a 
large number of questions selected from the papers 
of various examining bodies. 
NO. 2452, VOL. 98] 
(2) As its title implies, this text-book is purely 
descriptive in character. The subjects dealt with 
are mechanics of solids and fluids, light, heat, 
sound, electricity and magnetism. The ground 
covered is only elementary, and upwards of 200 
pages are devoted to introductory mechanics and 
properties of matter. No mathematical proofs of 
the formule employed are given, the idea being 
that the statements are to be regarded as laws to 
be verified experimentally. While there is nothing 
novel in the treatment of the subject, the text is 
accurate, concise, and amply illustrated. 
BIRDS AND THE POET. 
The Birds of Shakespeare. By Sir Archibald 
Geikie-> Pp. x+121. (Glasgow: James Macle- 
hose and Sons, 1916.) Price 3s. 6d. net. 
“THIS volume—one of the company of books 
which owe their existence to the tercen- 
‘tenary of Shakespeare—consists of an address 
delivered by the distinguished author to a country 
natural history society, and as such it must have 
served its purpose admirably. Beyond this it 
makes no pretensions, but it is all:that it claims 
to be, and will fill a vacant place on the shelves 
of those who do not possess Mr. J. E. Harting’s 
standard work. 
In his opening pages the author lays stress on 
the development of man’s feeling towards Nature 
from Chaucer to Shakespeare, from the simple, 
unreflective delight in the sights and sounds of 
the open air to the dawning of a sense of “the 
mystery of things ” and its influence on the human 
mind; and again, at the close of the lecture, he 
passes to the further development of reflectivity 
manifest in the poems of Wordsworth, Keats, and 
Shelley, where the birds are not merely talked 
about, however poetically, but actually talked to, 
as being, like ourselves, “travellers between life 
and death.”” The main body of the volume is taken 
up with the passages in the plays and poems 
relating te the several birds, linked together by 
pertinent observations. Some half-dozen pages 
are deservedly devoted to that “pleasure for high- 
mounting spirits”—the sport of hawking, to 
which the birds of prey owed such consideration 
as they enjoyed ; for, apart from this, Shakespeare 
shares the depreciatory attitude towards them 
current in his day and long after, including even 
the “mousing owl”; but then, as Waterton long 
ago remarked, from the time of Ovid downwards 
this useful bird has always been in ill odour with 
the poets. Passing on to the game birds, we get 
a too brief account of the various methods of 
taking them, and the sportsman to whom the 
“Diary of Master William Silence” is still an 
undiscovered treasure might have welcomed a 
footnote sending him to. that invaluable work. 
Here are one or two points which might receive 
attention when the book is reprinted. ‘The 
Passionate Pilgrim” and “The Phoenix and the 
Turtle” are drawn upon without any hint that 
these réchauffés are by no means wholly the work 
of Shakespeare. Loon, “a diver,” and loon, “a 
