May 8, 191 3] 



NATURE 



241 



to the testing' of engines, and reference is made to 

 the author's accelerometer ; we should like to have 

 found a more detailed account of this very in- 

 genious and useful instrument. Examples are 

 introduced in various portions of the work for the 

 student's exercise on points of theory, and answers 

 to many of these are given at the end of the 

 work, which concludes with a useful index. Both 

 in matter and style the book is much better than 

 many of the small elementary treatises that have 

 already appeared, while the printing and illus- 

 trations leave nothing to be desired. Altogether 

 this forms an attractive and useful little work 

 which will prove of real assistance to the student 

 in the earlier portions of his course. 



(3) In this tract of 78 pages are conveniently 

 collected data as to the physical properties of 

 special interest to the engineer of several liquid 

 substances, including alcohol, chloroform, carbon 

 tetrachloride, ether, ammonia, sulphur dioxide, 

 acetone, and carbon disulphide, together with 

 steam tables. The collection should prove useful 

 for purposes of reference ; the author uses British 

 thermal units and Fahrenheit degrees of tempera- 

 ture, and his figures will thus be immediately 

 available to the great majority of British engineers 

 to whom it is still difficult to think in metric and 

 centigrade units, notwithstanding the theoretical 

 advantages claimed for the metric system. 



In appendix i. the formula for chloroform 

 (CHC1 3 ) is incorrectly given as C 2 H0 3 , and 

 "carbon chloride" is used for carbon tetra- 

 chloride ; as there are several carbon chlorides it 

 seems desirable to distinguish clearly which is 

 referred to. 



The work is well got up, and contains numerous 

 tables and diagrams relative to the substances 

 dealt with, together with a discussion of the 

 limits of efficiency attainable theoretically with the 

 several liquid fuels considered. 



OUR BOOKSHELF. 

 Percentage Compass for Navigators, Surveyors, 

 and Travellers. By J. C. Fergusson. (London : 

 Longmans, Green and Co., n.d.) Price, un- 

 mounted, 2S. 6d. net ; mounted on linen, 

 35. 6d. net. 

 Mr. Fergusson' has apparently just discovered 

 what everyone knew before, viz., that at the angle 

 of 45 the natural sine is equal to the natural 

 cosine, or the one is 100 per cent, of the other, 

 and, being obsessed with the idea that the one 

 great object in life is to work out percentages, he 

 has taken the trouble to find the values of the 

 natural cosines when the natural sine has any per- 

 centage from 1 to 100 to those natural cosines. 

 He then divides the compass circle into octants, 

 and each octant into 100 unequal parts, or per- 

 NO. 2271, VOL. 91] 



centages, and states that by the use of these per- 

 centages Traverse tables are no longer required. 



What Mr. Fergusson has really done is to make 

 a new Traverse table where the natural cosine, 

 arranged in percentages in a circle outside the 

 compass, has to be multiplied by the percentage 

 course steered to obtain the natural sine. 



At present both natural cosine (diff. of latitude) 

 and natural sine (departure) can be obtained from 

 the ordinary Traverse tables for every degree of 

 the compass and for any radius between 1 and 300. 



Not only does Mr. Fergusson give a roundabout 

 way of obtaining a result which can be readily 

 extracted from the Traverse tables, but he also 

 seems to think that the natural cosines and sines 

 on a circle, the zero of which points to the mag- 

 netic north, will give the difference of latitude and 

 departure by utilising the percentages of the 

 octants on a compass card marked by his method. 

 These, it is scarcely necessary to point out, can 

 only be ascertained when the zero of the circle 

 points to the true north, or each course steered 

 has been corrected for the magnetic variation and 

 any local disturbance caused by a vessel's mag- 

 netism. 



An Essay on Hasheesh. Including Observations 

 and Experiments. By Victor Robinson. Pp. 

 83. (New York : " Medical Review of Re- 

 views," 1912.) Price 50 cents. 

 It is difficult to regard this booklet as a serious 

 contribution to medical literature. It consists 

 of about four score small, narrow pages, 

 about half of which are occupied by an account 

 of the hallucinations and rhapsodies experienced 

 by the author when under the influence of the 

 drug Cannabis sativa. What the precise value 

 of these observations is it is impossible to dis- 

 cover. It is no more practicable to subject them 

 to rational or systematic analysis than to attempt 

 to find reason or method in the incoherent ravings 

 of delirium. The particular manifestations in- 

 duced by Indian hemp must, of course, largely 

 depend upon idiosyncrasy, temperament, ante- 

 cedent and accidental conditions, and a host of 

 predetermining and fortuitous causes, and must 

 therefore vary from individual to individual and 

 differ, too, in different circumstances even in 

 the same individual. 



The only valuable section of the book is the 

 short digest of the little that is known from prior 

 work concerning the therapeutics and chemistry 

 of hasheesh. 



Life and Evolution. By F. W. Headley. Pp. 

 xx + 272. Second edition. (London: Duck- 

 worth and Co., 1913.) Price 5s. net. 

 The present does not differ greatly from the first 

 edition, which was reviewed in the issue of Nature 

 fur March 7, 1907 (vol. Ixxv., p. 434). Mr. 

 Headley has re-written a few pages, corrected 

 occasional inaccuracies, and replaced several un- 

 satisfactory illustrations by better. He has also, 

 in the light of new facts which have become avail- 

 able since the book appeared first, modified some 

 of his views. 



