NATURE 



[September i, 1921 



the species whence these timbers are derived. 

 Thanks to the labours of Sir \V, Schlich and Mr. 

 W. R. Fisher, whose " Manual of Forestry " was 

 published between 1889 and 1896, he is in a posi- 

 tion to apply the principles of forest management 

 with success under Indian conditions. But a gap 

 was left in his equipment. He was without a 

 systematic guide to the life-histories of those 

 forest essences the products of which it is his 

 business to dispose of to the best advantage. 

 The importance of the factors that govern repro- 

 duction and condition the growth and survival of 

 seedlings is now as fully realised in scientific 

 forestry as it is in scientific agriculture. 



Turning to account his own long and varied 

 Indian experience, Prof. R. S. Troup has 

 endeavoured to fill this gap by placing at the dis- 

 posal of his former colleagues a comprehensive 

 treatise on "The Silviculture of Indian Trees," 

 now published under the authority of the Secre- 

 tary of State for India by the Clarendon Press. 

 Modestly regarding his work as an incentive to 

 further study rather than an exhaustive presenta- 

 tion of his subject, Prof. Troup has fortunately 

 taken a broad view with regard to the species 

 dealt with. That a difficulty should have been 

 felt may easily be appreciated. The area ad- 

 ministered by the Indian Forest Department is of 

 wide extent and is diversely conditioned as re- 

 gards both soil and climate. It includes dry 

 plains, where the rainfall may be negligible, and 

 wooded escarpments with an annual precipitation 

 that may exceed 400 in. It contains tropical up- 

 lands well under the normal cloud canopy of the 

 rainy season, and temperate mountain valleys 

 swathed in mist for weeks at a time. It extends 

 from the mangrove forests at the outfalls of 

 Indian rivers to the upper limits of Himalayan 

 trees. The number of arboreal species met with 

 is necessarily great. Not all of these, however, 

 yield useful products ; many of those that do are 

 limited in distribution or occur but sparingly, so 

 that their timbers, though often employed locally, 

 are little known, if known at all, in commercial 

 circles. The decision to deal in this work with 

 most of the species the wood of which is known 

 to be of value will meet with the approval of all 

 who may use it, as will the further decision to 

 deal with the life-histories of exotics like those 

 Australian "gums " and American "mahoganies " 

 the cultivation of which has become definitely 

 established in India. But in dealing with the 

 trees thus included the author has shown a due 

 sense of proportion, for while the accounts of 

 elements so important as sal and teak, chir and 

 deodar constitute veritable monographs, trees of 

 NO. 2705, VOL. Io8"| 



minor consequence are discussed with commend- 

 able brevity. 



The illustrations with which the work has been 

 provided deserve especial notice. The series of 

 coloured plates in which seeds, germinating seed- 

 lings, and young plants are displayed are of great 

 interest and value ; the remaining drawings and 

 the photographs are well chosen, carefully repro- 

 duced, and always instructive. 



Prof. Troup will doubtless prove justified in 

 his hope that this work may induce further re- 

 search in what is a fascinating and important 

 field. Meanwhile it is possible to say that, as a 

 complement to those of his distinguished pre- 

 cursors, his work is worthy of the aegis under 

 which it has been produced, and will prove as 

 indispensable to the Indian forest officer as that 

 of Gamble on "Indian Timbers" and that of 

 Brandis on "Indian Trees." 



The Works of Cavendish. 



The Scientific Papers of the Honourable Henry 

 Cavendish, F.R.S. Vol. i : The Electrical Re- 

 searches. Edited from the published papers 

 and the Cavendish manuscripts in the possession 

 of his Grace the Duke of Devonshire, K.G., 

 F.R.S., by Prof. J. Clerk Maxwell. Revised 

 by Sir Joseph Larmor. Pp. xxviii-h452. 

 Vol. 2 : Chemical and Dynamical. Edited from 

 the published papers and the Cavendish manu- 

 scripts in the possession of his Grace the Duke 

 of Devonshire, K.G., F.R.S., by Sir Edward 

 Thorpe, with contributions by Dr. Charles 

 Chree and others. Pp. xii-f496-i-6 plates. 

 (Cambridge: At the University Press, 192 1.) 

 61. net 2 vols. | 



HE Cambridge edition of the scientific papers j 

 of Henry Cavendish is much more than a 1 

 mere reprint. In 1879 an edition of the electrical 

 researches was published, a 'work to which Clerk 

 Maxwell, the first Cavendish professor of experi- 

 mental physics, devoted the last five years of his 

 life. This long period was required because 

 Cavendish had left behind, in addition to his 

 papers in the Philosophical Transactions, a manu- 

 script record of many experiments which were 

 not published, but were sufficiently precise to 

 prove that he was familiar with the theory of 

 divided currents ; had made a most extensive series 

 of experiments on the conductivity of saline solu- 

 tions in tubes, compared with wires of different 

 metals ; and had found out the inductive capacity 

 of glass, resin, and wax. These manuscripts 

 occupy 255 pages of the present edition as com- 

 pared with sixty-six pages which are covered by 



T" 



