332 



NATURE 



[November 26, 1914 



sociation-curve of the haemoglobin as an indicator 

 of the reaction of the blood, and contains a wealth 

 of interesting observations on the effects of diet, 

 exercise, residence at high altitudes, and finally, 

 certain pathological conditions associated with 

 acidosis. The author is to be congratulated on 

 the production of a book interesting not to 

 physiologists only. The lively personal note of 

 the narrative is a happy novelty in a physiological 

 monograph, and will enable those of his readers 

 who have not worked with him to appreciate and, 

 in a measure, to partake of the genial optimism of 

 the author. E. H. S. 



GYROSCOPIC MOTION. 



An Elementary Treatment of the Theory of 

 Spinning Tops and Gyroscopic Motion. Second 

 edition. By H. Crabtree. Pp. xv + 193. 

 (London: Longmans, Green and Co., 1914.) 

 Price '^s. 6d. net. 



IN this, the second edition of Crabtree 's 

 admirable book, the text and paging of the 

 first edition have been followed, but additions 

 have been made where necessary, so that more 

 recent developments may be dealt with. The first 

 edition was noticed in Nature (August 12, 1909, 

 p. 182), so that it is not necessary to do more 

 now than refer to the additional matter. The two 

 monorail systems of Brennan and Schilowsky are 

 illustrated and described. It may be mentioned 

 that each of these derive their stability from a 

 gyrostatic system, the action of which is inde- 

 pendent of the forward motion of the car, so that 

 the stability exists whether the car is moving 

 forwards or backwards or is at rest, and in this 

 respect differs entirely from the systems more 

 recently invented by Dr. Gray. 



There is a full discussion of the Anschiitz gyro 

 compass, but this is the same as that which is 

 given in the manual published by Messrs. Elliot 

 Bros., having been translated for them by the 

 author and his colleagues. The writer of this 

 notice hoped to have found also a description of 

 the Sperry gyro compass, which differs in certain 

 respects very materially from its forerunner, the 

 Anschutz. A discussion by the author of the 

 relative merits of the two systems where they differ 

 would have been very illuminating. Unfortun- 

 ately, this instrument is not mentioned. Other 

 matters ably dealt with in the appendices are the 

 swerving of golf-balls and the drifting of rifled 

 projectiles, both subjects on which amazing non- 

 sense is often written. 



There is a statement in the earlier part of the 



book on the skidding of motor-bicycles, with which 



the present writer does not agree. Seeing that 



the back tyre is being constantly impelled to slip 



NO. 2352, VOL. 94] 



longitudinally on the ground by successive explo- 

 sions in the cylinder, more especially where a 

 rigid chain drive is employed, or where the fly- 

 wheel of the engine is insufficient, and that a 

 longitudinal slip will start a side slip, there is 

 abundant cause for the side-slipping capacity of 

 these machines, without looking to more subtle 

 causes. Briefly, the author explains that in con- 

 sequence of the gyrostatic action of the flywheel 

 a transverse couple must be applied in order to 

 make the flywheel's plane of rotation change when 

 the machine is describing a curve. In order to 

 apply this, the rider and machine must lean over 

 to a very small extent more than would be neces- 

 sary otherwise. So far so good ; the transverse 

 couple is caused by the weight of the whole com- 

 bination of machine and rider acting vertically 

 downwards, and a corresponding reaction at the 

 road acting vertically upwards, and the arm of 

 the couple is the excess of the horizontal distance 

 between the centre of gravity and the wheel base 

 due to the extra leaning. The transverse force 

 on the road, which alone gives rise to side slip, 

 is unchanged. 



It is satisfactory to find that there is a suflficient 

 demand for a book of such thoroughness as this 

 to have called for a second edition in a compara- 

 tively short time. C. V. Boys. 



BRITISH FLOWERING PLANTS. 

 British Flowering Plants. Illustrated by Three 

 Hundred Full-page Plates, reproduced from 

 Drawings by Mrs. Henry Perrin. With 

 Detailed Descriptive Notes and an Introduction 

 by Prof. G. S. Boulger. Vol. i. Pp. xlv + 

 plates. (London : Bernard Quaritch, 1914.) 



MRS. PERRIN 'S book, of which the first 

 volume is before us. is essentially a book 

 for the use of ladies and those who take a dilet- 

 tante interest in botany and flowers. It is un- 

 fortunate, therefore, that it is of such a weight 

 that its presumed readers may scarcely have the 

 strength or energy to handle the bulky tomes. 



Not only are the plates heavily loaded with 

 plaster of Paris, but the large quarto pages of 

 text are of almost equal solidity. If the contents 

 of the book were of any scientific interest or 

 formed a real addition to knowledge, the great 

 bulk of the volume would be a matter of sincere 

 regret ; we cannot, however, foresee any particular 

 use for the book, except that its handsome back 

 may adorn the shelves of an expensive library, and 

 can only deplore that the money expended on this 

 production could not have been put to some object 

 of definite botanical value. 



The paintings, which afford the raison d'etre 

 of the book, are on the whole good, though in 



