Marcu 7, 1907 | 
NATURE 
aI 
(5) The revised and enlarged edition of Stewart's 
‘Light’ contains a very full treatment of the 
elements of geometrical optics. The inclusion of a 
large number of simple practical experiments enhances 
the value of the volume considerably. Dispersion 
and spectrum analysis receive a fuller treatment than 
in the previous edition. The book will prove distinctly 
useful. 
(6) An introductory text-book of theoretical physics, 
the subject-matter having been selected with refer- 
ence primarily to its value as part of a general educa- 
tion. Problems are interspersed at frequent intervals, 
and some of these are well designed to make a student 
think. A great deal of care has been exercised in 
the compilation of this book. 
(7) This text-book of physics, which includes 
mechanics, heat, light and sound, electricity and 
magnetism, has been written for pupils in the 
American high schools. The statements are concise, 
and the diagrams clear. It is thoroughly up to date, 
and will prove a very suitable introductory course, 
especially if, as the author intends, laboratory work 
is carried out at the same time. 
(8) The author in his preface intends this book for 
that class of technical students who are ignorant of 
the rudiments of algebra, geometry, trigonometry, 
and mechanics. The book includes three introductory 
exercises, six exercises On magnetism, and twenty-six 
on current electricity and its applications. There is 
very little in the method of treatment to distinguish 
it from other elementary text-books of practical elec- 
tricity and magnetism. It is doubtful whether a 
student will draw a correct idea as to what deter- 
mines a sparlx in air from the statement on p. 30 :— 
“Join 1 ft. of copper wire to one terminal (of a 
Leclanche cell) and brush the other terminal with 
the free end of the wire. No spark is seen because 
the E.M.F. of the cell is only about 1.3 volts and the 
resistance is high, so the maximum current is very 
small.’’ 
And on p. 32 (repetition with storage cell) :— 
“The E.M.F. is about 2 volts, and the resistance 
is very small, so the maximum current is large. 
Sparking is abundantly shown.”’ 
No thoughtful teacher would instruct a student to 
count the number of vibrations a magnet makes in a 
given time, as in the experiment described on p. 13. 
Elementary electrostatic experiments are omitted, as 
these are thought to be relatively unimportant and 
difficult. There is little to recommend this book when 
compared with some excellent introductions which 
have appeared in recent years. 
OUR BOOK SHELF. 
Animal Artizans and other Studies of Birds and 
Beasts. By €. J. Cornish. Pp. xxxiv+274; 
illustrated. (London: Longmans, Green and Co., 
1907.) Price 6s. 6d. net. 
Tue late Mr. Cornish was a constant contributor of 
articles bearing upon natural history matters to the 
columns of the Spectator and Country Life, and the 
present volume, which is edited by his widow, con- 
sists mainly of a reprint of articles from those 
NO. 1949, VOL. 75 | 
journals, with such modifications as the course of 
time has rendered necessary or advisable. In some 
cases the articles had been revised with a view to 
publication in book form by Mr. Cornish himself, 
but where this had not been done in the author’s 
lifetime the task devolved upon the editor. 
The volume opens with a brief account of the life 
of Mr. Cornish, which will no doubt be welcome 
to the numerous readers who find entertainment or 
instruction in his works. Following this are several 
articles, upon which the title of the volume is 
evidently based, some of these dealing with the works 
of such birds as the South American oven-bird and 
our own woodpeckers, while *‘ road-making animals ”’ 
and “ landscape-gardeners’’ form the subjects of 
others. Several of these articles display a lament- 
able want of knowledge of scientific zoology on the 
part of the author. We are told, for instance, on 
p- 34, that ‘‘the musk-ox, the ovibos, is as 
much akin to the sheep as to bovidae, and 
in habits more like what we imagine the un- 
descended great wild original of our sheep was than 
are the wild sheep of to-day.’”? In regard to the 
first half of the sentence, it is now accepted that 
the musk-ox is not a near relative of either sheep or 
oxen, while the whole group is included in the 
Bovide. As to the meaning of the second half of 
the sentence, we are altogether in the dark. Again, 
on p. 48 we notice the astounding information that 
the pampas stag is the only large ruminant on the 
plains of South America, which, by the way, are 
stated to be formed of clay. Other similar cases 
might be cited, but in the case of a posthumous work 
criticism must not be too trenchant; and, after all, 
the volume is perhaps sufficiently accurate to suit 
the requirements of the readers to whom it is likely 
to appeal. 
Rubber in the East. Being the Official Account of 
the Ceylon Rubber Exhibition held in the Royal 
Botanic Gardens, Peradeniya, in September, 1906. 
Edited by Dr. J. C. Willis, M. Kelway Bamber, and 
E. B. Denham. Pp. 269; illustrated. (Colombo: 
H. C. Cottle, Government Printer.) 
Tuts interesting and up-to-date work is the official 
account of the Ceylon Rubber Exhibition held in the 
Royal Botanic Gardens, Peradeniya, in September, 
1906 (see NaturE, December 27, 1906, p. 209). The 
duration of the exhibition allowed of its being a 
Rubber Congress, lectures being given upon the 
various branches of the subject from cultivation to 
vulcanisation. These lectures, discussions, judges’ 
reports, &c., have been brought together in the 
present volume and arranged in a logical order with 
the hope of making this account a standard treatise 
upon the rubber industry as it at present exists. 
The chapters dealing with the cultivation of rubber 
in Ceylon and other countries, treatment of diseases, 
tapping knives, machinery for the treatment of latex, 
and the shipment and marketing of rubber, should 
prove valuable aids to the practical rubber grower. 
Some idea of the rapid growth of the industry is 
gathered when we see that five years ago there were 
only 2500 acres under rubber in Ceylon, and to-day 
104,000 acres, the Hevea brasiliensis being the species 
most extensively planted. This tree produces the 
well-known Para rubber, which, prepared in the 
ordinary way, possesses 90 to 95 per cent. of caout- 
chouc. The Hevea appears to stand tapping operations 
even when of a very drastic nature. 
High tapping has been tried on some plantations 
up to 3oft. and soft., and this system gives in some 
cases 12lb. to 14lb. of rubber per tree; but there is 
