124 



NATURE 



[December 6, 1894 



their various opinions. The chapter on the Chaldaean 

 civilisation is interesting, and is full of curious infor- 

 mation. The volume is concluded by an appendix treat- 

 ing of the Pharaohs of the Ancient and Middle Empires, 

 and by a useful index. M. Maspero is fortunate in 

 having found so careful a translator as Mrs. McClure, 

 who introduces her work in a preface which is at once 

 business-like and to the point. The editor's remarks 

 are, however, somewhat rambling, and in professing to 

 criticise M. Maspero's knowledge of matters Egyptian or 

 Babylonian, we think greatly out of place. 



THE TRAXSMISSION OF POWER. 

 On the Dei'tlopment and Transmission of Power. By 

 William Cawthome Unwin, F.R.S. (London : Long- 

 mans, Green, and Co., 1S94.) 



IT is well known that the author of this work has had 

 special opportunities for studying the subject of 

 transmission of power by all the various methods which 

 have, at different times, been adopted, and the engineering 

 world is to be congratulated on having received from his 

 pen a summary of the principles utilised in this class of 

 work, and of the possibilities of the future, as well as 

 very complete and authentic information about the 

 principal work that has been done In the past. This book 

 is ihe outcome of a course of " Howard' lectures de- 

 livered before the Society of Arts in 1893. It deals with 

 the generation, storage, and transmission or distribution 

 of power. The methods of transmission and distribution 

 Include water under pressure, compressed air, wire ropes, 

 steam, gas and electricity. The author recognises the 

 fact that transmission of power to distances has not been 

 so fully developed in the past as it is likely to be 

 shortly, and that the electrical transmission and distri-. 

 bution of power has more to claim in the way of promises 

 for the future than large achievements in the past. 



The first chapters deal with the generation and the 

 cost of generating power by steam or hydraullcally. 

 One of the most valuable parts of the book is found in 

 those chapters where the economy of steam engines is 

 considered. These chapters deal with the losses in 

 boiler and engine In a very complete manner. The author 

 has realised very fully the fact that In any case of 

 generating power in large quantities, and distributing it 

 to small consumers, the cost of the horse power depends 

 largely upon the load curves at different times of the day, 

 and he draws attention to the very large excess of cost 

 per horse power of electric lighting stations over those 

 which are delivering power at a constant rate. Even in 

 a pumping station where the work is continuous, he finds 

 that about 35 per cent, more fuel is required than in a 

 careful trial, but in a station from which electric light or 

 power is distributed, the losses due to banking of boilers 

 and to engines working a portion of their time at an out- 

 put which is not economical, are such that the quantity 

 of fuel used per indicated horse power rises from \\ lbs. 

 per hour in a test trial with a condensing engine, to 

 3'3 lbs. under the special circumstances. The relative 

 advantages of the condensing and non-condensing 

 engines of the simple, compound, and triple expansion 

 engines, of the slcam-jacketing and superheating, are all 

 discussed admirably. Some pages also are devoted to 

 NO. I 3 10, VOL. 51] 



the utilisation of house refuse as a fuel, and the Halpin 

 system of thermal storage receives some attention. 



Some of the most important cases of utilising water 

 power are also discussed. It will surprise many readers 

 to find that even in 1876, 70,000-horse power was gene- 

 rated for manufacturing purposes from waterfalls in 

 Switzerland, and that in the United States in 1880,36 

 per cent, of the power used in manufacturing was water 

 power, and only 64 per cent, steam power. 



Among the chapters devoted to transmission of power, 

 the most important, as pertaining more especially to the 

 author's experience, are those on hydraulic and com- 

 pressed air transmission. But in all branches of the 

 subject, not only are the general principles dealt with, but 

 there is to a pretty full extent a recapitulation of what 

 has already been done. The London Hydraulic Power 

 Company is taken as the best example of hydraulic 

 transmission, but Liverpool, Birmingham and Manchester 

 .ire also referred to, whilst most interesting accounts of 

 the hydraulic supply at Zurich and Geneva are given. 

 The principles of pneumatic distribution are very com- 

 pletely described, and the author has certainly made out 

 the case that when these principles are properly applied, 

 this system of distribution deserves more consideration 

 than is generally accorded to it. Naturally the Paris 

 distribution by this method is dealt with very fully, but 

 other examples of Interest are added. With regard to 

 the distribution of power by steam, the most important 

 case is that of New York, which Ur. Emery started In 

 1 88 1. Eight pages upon gas distribution for power 

 purposes are well worth some study, whether with regard 

 to manufactured gas, or the natural gas supply in Penn- 

 sylvania. Whilst compressed air receives the author's 

 attention to the extent of forty-eight pages, electrical 

 distribution is by no means so well favoured ; but the 

 author explains that, in the first place, it is not his own 

 speciality, and, in the second place, there are at the 

 present moment few cases of electrical transmission 

 combined with a complete system of distribution in a 

 town. A chapter is at the end devoted to the great 

 work which is now approaching its full development at 

 Niagara Falls. 



This short review cannot pretend to give an adequate 

 Idea of the contents or value of Prof. Unwin s book. 

 Regarding the merits of the work generally, it is sufficient 

 to say, first, that throughout it is written with the utmost 

 fairness and impartiality ; and secondly, that if any 

 engineer were planning a system of transmission and 

 distribution of power in any special case, he would be 

 labouring under very considerable disadvantages if he had 

 not first consulted this latest and most complete work on 

 the development and transmission of power. G. F. 



OUK BOOK SHELF. 



A Treatise on Hygiene and Public Health. By Thomas 

 Stevenson, M.D., F.R.C.P., and Shirley F. Murphy. 

 (London : J. and A. Churchill, 1894.) 



This volume is devoted to the subject of sanitary law, 

 and it well maintains the all-round excellence of the two 

 volumes that preceded it. Health officers will welcome 

 the appearance of such a lucid and comprehensive digest 

 of the law relating to the public health in England and 

 Wiiles, Ireland and Scotland. 

 iJuring comparatively recent years an immense amount 



