March 17, 188 7 J 



NA 7 URE 



461 



not quite easy of reference). Five of these treat of 

 general subjects, and the rest of particular machines or 

 details. 



The work opens with a well-written summary (i6 pp.) 

 of what is known of the flow of water under pres- 

 sure, including a statement of the formuku from Torricelli 

 down to our own day, with a short account of some o 

 the more recent experiments. Then follow some 

 " General Observations," in which it is explained that 

 the fears entertained on the first introduction of high- 

 pressure water-power that accidents would bo frequent 

 from the bursting of pipes, especially in frosty weather, 

 have proved groundless. The " relief-valves " necessary 

 to avoid the shock from suddenly stopping or changing 

 the motion of a non-elastic fluid like water are described 

 and drawn. In another chapter the author describes the 

 mode of "packing" so as to produce joints tight under 

 high water-pressure, explains the use of "cupped leathers" 

 to form a self-tightening joint, and shows the necessity of 

 clear water, since dirty or gritty water causes rapid wear 

 of the leathers. 



The advantages of " power co-operation " all over large 

 towns are considered in a short chapter (6 pp.), and 

 illustrated by its successful application at Kingston-upon- 

 Hull. Much more space might have been given to this 

 now very important branch of the subject. A short 

 chapter (6 pp.) details the cost of water-power in various 

 places : it seems to vary from ^ of a perny, to nearly id. 

 per ICO foot-tons. 



There are three chapters (covering only 7 pp. in all) 

 on water-wheels, turbines, and centrifugal pumps. These 

 chapters are too short to be of any practical use. 

 The remaining 37 chapters are almost entirely devoted 

 to the description of the appliances necessary for the use 

 of high-pressure water-power, and to the very varied 

 machines which may be thereby worked : inany of these — 

 especially the larger and more recent machines — are very 

 fully illustrated. All this part of the work is of great 

 interest. The pressure required for various purposes is 

 stated to be 700 lbs. per square inch for ordinary hydraulic 

 machines, 1500 to 2000 lbs. for shop-tools, and up to 

 20,000 lbs. for compressing iron and steel ; and the ad- 

 vantages in the use of high-pressure are explained. The 

 conditions to which this hydraulic power is suitable are 

 shown to be those in which great power is to be exerted 

 at scattered points for a short time only, and at irregular 

 intervals. The machines and appliances described and 

 illustrated are very numerous and diversified — far too 

 many to enumerate here. Among the more interesting 

 may be mentioned cranes, riveters, dock-gear, swing- 

 bridge-gear, steering- and ship-gear, gun-lifts, and hoists 

 of all sorts. 



The practical part of this work is excellent : it is, in 

 fact, a short monograph on the use of high-pressure 

 water-power. But the theoretical part sadly needs re- 

 vision. The term "power" is loosely used, sometimes 

 meaning "force " (say in pounds), sometimes " work " (say 

 in foot-pounds), sometimes " horse-power " (of 33,000 foot- 

 pounds per minute). It is not surprising, therefore, to 

 find the following mistakes: (i) a factor, 60 {i.e. 60 

 seconds in a minute), omitted in computing " horse- 

 power " on p. 24 ; {2) a factor, 33,000, omitted in computing 



" horse-power " on p. 27, also the units (feet and pounds) 

 not mentioned in same place ; (3) a result on p. 35, which 

 seems to be inch-pounds -^ 33,000 {i e. -r-by foot-pounds 

 per minute) marked as H.P. ; (4) the following on p. 98, 

 " the power (or foot-pounds) transmitted through a high- 

 pressure water-main is determined by multiplying the 

 fnumber of pounds of water flowing per second by the 

 pressure." From a numerical example lower down it may 

 be seen that the " power" referred to in this sentence is 

 to be estimated (not in foot-pounds, but) in foot-pounds 

 per second, and that by "pressure" is meant head of 

 pressure, in feet, 



Allan Cunningham, Major, R.E. 



OUR BOOK SHELF 



TheStatesmaii's Ycdr-Book for liZ-]. Edited by J. Scott 

 Keltie. (London: Macmillan and Co., 1S87.) 



This work is so well known and so generally appre- 

 ciated that it is necessary merely to note the appear- 

 ance of the volume for 18S7. The editor has made 

 every effort to bring the statistics up to the latest date, 

 and those who have been in the habit of referring to the 

 book will find that its value has been considerably in- 

 creased by important additions and modifications. An 

 adequate account of the smaller British colonies has 

 been introduced, and much new information is given 

 with regard to the various systems of land-tenure in 

 India. The leading facts brought out by the new 

 censuses in Germany and France are embodied, and 

 Mr. Keltie has been careful to show the precise 

 results of the recent colonial enterprises of these two 

 countries. 



Joint Scientific Papers of James Prescott Joule, F.R.S. 

 Published by the Physical Society of London. (Lon- 

 don : Taylor and Francis, 1887.) 



Among the contents of this volume are some elaborate 

 papers on " Atomic Volume and Specific Gravity," pre- 

 pared by Mr. Joule in association with Sir Lyon Playfair. 

 Mr. Joule took the principal part in the experiments on 

 the expansion of salts, the maximum density of water, 

 i.S:c. ; but the important theoretical results arrived at with 

 regard to atomic volume he attributes almost entirely to 

 his colleague. Another valuable series of papers were the 

 joint work of Mr. Joule and Sir William Thomson. The 

 subjects are : " The Thermal Efl'ects experienced by Air 

 in rushing through Small Apertures," and " The Thermal 

 Effects of Fluids in Motion." In the year 1S43, Mr. 

 Joule read a paper on "The Caloric Effects of Magneto- 

 Electricity and the Mechanical Value of Heat," to the 

 Chemical Section of the British Association assembled at 

 Cork. The subject did not excite much general attention, 

 so that, when he brought it forward again at the meeting 

 in 1847, the Chairman suggested that he should not read 

 his paper, but confine himself to a short verbal descrip- 

 tion of his experiments. "This," says Mr. Joule, "I 

 endeavoured to do, and, discussion not being invited, the 

 communication would have passed without comment if a 

 young man had not risen in the Section, and, by his 

 intelligent observations, created a lively interest in the 

 new theory. The young man was William Thomson, 

 who had, two years 'previously, passed the University of 

 Cambridge with the highest honours, and is now pro- 

 bably the foremost scientific authority of the age." The 

 work they afterwards did together, the results of which 

 are here recorded, was chiefly experimental, performed 

 in Manchester and the neighbourhood. 



