November 15, 1900] 



NA TURE 



57 



saving effected in raising the coal. At one mine where 

 three of Watt's engines were erected the proprietors en- 

 gaged to pay 800/. a year for each engine as a compromise 

 for the third part of the saving in coal. 



It was with the Cornish engine that the principles 

 governing steam engine economy were first grappled 

 with ; and with the engines used for all purposes on 

 land, pumping engines, even at the present day, are 

 worked with the greatest economy of fuel, examples 

 being given where the engines are worked with an ex- 

 penditure of less than 2 lbs. per I.H.P. It is interest- 

 ing to note the change of pressure at which steam is 

 worked now, reaching to 150 lbs. on the square inch, as 

 compared with the 5 lbs. used in many of the old Boulton 

 and Watt engines. These engines were not confined to 

 pumping water from mines, but were applied to reclama- 

 tion purposes, many of the Boulton and Watt engines, 

 made a century ago, being still in use in the fens .of 

 Lincolnshire and Cambridgeshire. These machines 

 were noted for their massive construction and the ex- 

 cellency of the workmanship, as attested by the number 

 of years during which they have done good service. 



The other fourteen chapters into which the book is 

 divided deal with descriptions of the various types of 

 pumping engines in use ; pumps and pump valves ; pit 

 work ; shaft-sinking ; hydraulic transmission of power in 

 mines ; valve gears ; waterworks engines ; trials of 

 pumping engines ; centrifugal and low lift pumps, with 

 descriptions of some of the scoop wheels in use in Holland; 

 hydraulic rams and pumping mains. 



Elements of Hydrostatics. By S. L. Loney, M.A. Pp. 

 viii -f- 248 4- xii. (Cambridge: University Press, 

 1900.) 

 "Elements of Hydrostatics" is a subject the limits 

 of which are sufficiently well known to require little de- 

 finition. In the present instance it includes a fairly com- 

 plete treatment of centres of pressure of rectilinear areas 

 and circles by what used to be called, at Cambridge, 

 " three-day methods " — also sections on rotating liquids 

 and on tensions of vessels and curves of buoyancy. The 

 book will do admirably for the ordinary run of students pre- 

 paring for examinations in this subject, and the copious 

 problems and examples should commend it to science 

 students ; but there are one or two points in which im- 

 provement is desirable. " Whole pressure " has been too 

 long a fetish of the third-rate schoolmaster, who " thinks 

 he is wise when he is not." But instead of banishing 

 this misleading idea to a few lines of small print (or, 

 better, omitting it altogether), and replacing the term 

 " whole pressure " elsewhere hy " resultant thrust on a 

 plane area," Prof Loney makes confusion worse con- 

 founded by speaking, so far as we can make out, indis- 

 criminately of " whole pressure," " whole pressure or 

 thrust " and " whole thrust." Again, there is no reason 

 why we should be left in the dark as to the precise dis- 

 tinction between a perfect fluid and an ordinary fluid, or 

 the reason why the principles of hydrostatics apply with 

 sufficient approximation to the latter ; these points are 

 hinted at, but might with advantage be stated more 

 explicitly. The usual figure of the air-condenser, with 

 its valves hanging in an impossible position, is once 

 more reproduced. 



There are, to our knowledge, many highly successful 

 teachers who, in their ignorance, persist in their prefer- 

 ence for misleading methods of dealing with such notions 

 as "whole pressure," the "parallelogram of velocities," 

 the "binomial theorem" and the like. There are i&^N 

 writers better qualified to prove that scientific accuracy is 

 not incompatible with a successful text-book than Prof. 

 Loney, whose name alone is sufficient to ensure a large 

 circulation for his works. Why, too, does not the 

 Cambridge University Press rise superior to pandering 

 to the fancy of those mathematical masters who know no 

 better ? 



NO. 1620, VOL. 63] 



Min^ralogie Agricole. By F. Houdaille. Pp. 299, avec 

 107 figures dans le texte. (Paris : F^lix Alcan, 1900.) 



The object of this little work is to provide agriculturists 

 and others with a knowledge of the properties, physical 

 and chemical, of the minerals important to man, either 

 as constituents of rocks and soils, as fertilisers or as- 

 sources of materials used in the arts. The author 

 assumes ignorance of physics, chemistry and crystallo- 

 graphy on the part of the reader, and as the descriptive 

 portion of the book would be unintelligible without some 

 knowledge of these subjects, he attempts to give the 

 necessary smattering in an introduction of eighty-nine 

 pages. The laws of crystallography and modern views 

 of crystal structure are dealt with in forty pages, illus- 

 trated by a number of indifferent figures, some of which,, 

 notably the rhombohedron of Fig. 8, entirely fail to 

 produce on the eye the effect which the author presum- 

 ably intended. In the chemical section the old 

 equivalent notation is preferred to that usually accepted 

 at the present day ; thus, sodium carbonate receives the 

 formula NaO,C02-f- loHO ! A considerable portion of 

 the space devoted to analysis is occupied by a picture of 

 an elegant gentleman puffing languidly with a blow-pipe 

 at a long candle fixed in an equally tall candlestick. 

 The rest of the book contains a selection of facts about 

 minerals which can be found in any treatise on descrip- 

 tive mineralogy, together with some useful information 

 as to methods of determining the permeability of soils 

 and the percentage of calcium carbonate contained in 

 them. We fear, however, that the work will hardly be 

 found readable by any one who has not already had an 

 extensive training in chemistry and mineralogy. It is 

 therefore unlikely to be of much value to the class for 

 whom it appears to be intended, nor can it be recom- 

 mended to the serious student. 



Engine-Room Practice. A Handbook for the Royal 

 Navy and Mercantile Marine. By John G. Liver- 

 sedge, R.N. Pp. xi. -f 292. (London : Griffin and Co., 

 Ltd., 1899.) 



Mr. Liversedge's handbook will be found by all en- 

 gineers to be a very useful supplement to the more 

 technical treatises of Mr. Seaton and of Messrs. Sennet 

 and Oram. It lays down the whole duty of a marine 

 engineer, and more particularly of a naval engineer, from 

 the day when he receives notice of his appointment ; and 

 it is throughout well-written, full, and admirably to the 

 point. The running of the main engines and the care of 

 the boilers are, of course, the chief concerns of the book ;. 

 but the auxiliary machinery is also well looked after, and 

 there are separate chapters on the electric light, the 

 hydraulic, the refrigerating and the air-compressing 

 plants. The chapter on adjustments and repairs seems 

 to us of especial value, for while a successful repair at 

 sea is often the outcome of what seems an inspiration, 

 its success may at any time be assured by a knowledge 

 of what has been done in similar cases. 



We could wish, especially in the present season of 

 divergent opinion on the matter, that the water-tube 

 boiler had received somewhat greater attention. A i&w 

 pages at the end of the book are specially contributed by 

 Fleet Engineer Edwards, of H. M.S. Powerful, and per- 

 haps it were unwise to do more until fuller experience 

 has been gained ; but we may expect to see the matter 

 thoroughly taken up in later editions, for no unprejudiced 

 observer can doubt that the water-tube boiler, in one form- 

 or another, has come to stay. 



While Mr. Liversedge's book is primarily a professional- 

 handbook, it will be found, at the same time, to interest 

 all who have any acquaintance with the engineering side 

 of naval life, even though they may have but a superficial 

 knowledge of the ordinary equipment of a ship's engine- 



