March i i, 1909] 



NA TURE 



paration of salt cake is dismissed in a single equation 

 (which is arithmetically incorrect) as if it took place in 

 one stage only ; not a word is said about the forma- 

 tion of acid sulphate, or about the reverse action of 

 hydrochloric acid on sodium sulphate, nor is the matter 

 dealt with under either sodium chloride or the sodium 

 sulphates. Then there is a discrepancy between the 

 statement here, regarding the reduction of sodium 

 sulphate, and that on p. 270; according to the former, 

 the action is represented by the equation 



Na„SO, + 2C = Na„S + 2CO,, 

 and the formation of carbonic oxide is due to the later 

 interaction of coke and calcium carbonate; according 

 to the latter, the reduction of sodium sulphate produces 

 carbonic oxide, though the action is complicated by 

 the formation of some carbonic anhydride. 



In connection with the description of processes for 

 manufacturing soda, a curious slip of quite a different 

 kind is made. On p. 298 there occurs the statement : — 



" Es ist daher wohl nur eine Frage der Zeit, wann 

 dieses \'erfahren [ammonia process] den Leblanc- 

 Prozess vollstandig verdriingt haben wird." 



.And then, three lines further down : — 



" In neuester Zeit endlich wird auch das .Solvay- 

 \'erfahren durch die direkte Sodagewinnung aus 

 Koclisalz mittels des olektrischcn Stromes in den 

 llintergrund gedrangt. " 



There is an undesirable lack of precision about 

 statements such as that on p. 4^2, that rubidium per- 

 sulphate has been prepared " by electrolytic oxidation 

 of a saturated solution of the sulphate in presence of 

 sulphuric acid." Here and there, also, there is room 

 J'or criticism regarding inconsistency in the formulae 

 used to represent elements in some of the equations. 

 On p. 681, in connection with the action of chlorine 

 on silver nitrate, the chlorine appears in the equation 

 as 3CI2, but on p. 6go, in the equation for the precisely 

 analogous action of bromine, this appears as 6Br. 

 In equations to represent actions which involve 

 •' nascent " hydrogen, it would be better to avoid 

 using the molecular formula H„,. which appears on 

 p. 91. 



Throughout the whole book, however, the occasions 

 for criticism are gratifyingly few in number. 



MECHAMi AL EXGIKEERIXG. 

 (i) Lathe Design for High- and Low-Spccd Steels. 

 By Prof. John T. Nicolson and Dempster Smith. 

 Pp. X-I-402. (London : Longmans, Green and Co., 

 190S.) Price i8i. net. 



(2) Meehaitics of Engineering. By Prof. Irving P. 

 Church. Revised edition, partly re-written. Pp. 

 xxvi + 854. (\ew York: John ^^'iley and Sons; 

 London : Chapman and Hall, Ltd., 190S.) Price 

 2^s. 6d. net. 



(3) .Motor-car Mechanism and Management. Part ii. 

 Electric and Petrol-electric Vehicles. By W. 

 Poynter Adams. Pp. .\-(-202. (London : Chas. Grittin 

 and Co., 1908.) Price 55. net. 



(i) 'T'HIS treatise is based largely upon two impor- 



-I- tant pieces of research work carried out by 



the authors at the Manchester Municipal School of 



NO. 2054, VOL. 80] 



Technology — the one on the durability of tool steel, 

 the other upon the cutting forces acting upon lathe 

 tools ; these researches have been published already in 

 the form of reports ; the practical side of the book is 

 also based upon data and particulars furnished to the 

 authors by machine-tool makers. 



The book is, therefore, a successful attempt to 

 supersede the empirical rules which have hitherto 

 governed the design of these machine tools, and to 

 substitute for them methods based upon experiment- 

 ally ascertained facts ; the general adoption of high- 

 heat steel had, in fact, rendered obsolete much of the 

 accumulated data of the tool-maker, and some change 

 in methods of design was therefore essential, and, in 

 offering a solution of this problem, the authors have 

 fully realised that the economic or commercial side 

 of the question must be taken into account as well as 

 the scientific. 



The first few chapters are devoted to an account 

 of the authors' experiments, already alluded to, the 

 results being given in tabular form and in the form 

 of curves ; the experimental results so obtained are 

 then applied to the design of lathes for high-speed 

 cutting and for low speeds, and fgr what the authors 

 term compromise lathes also ; such problems as 

 greatest and least spindle speeds, number of speeds, 

 and the belt drive are fully discussed. 



In chapters xix. to xxi. the principal designs of 

 the fast hcadstock and its gear arrangements are 

 described, both when the cone is mounted on the 

 spindle and when it is off it, and also when the 

 cone is replaced by a single pulley, and all variations 

 of speed are obtained by gearing. Then follow 

 chapters devoted to the general principles which 

 underlie the choice and design of such fast head- 

 stocks, the chapter devoted to the design of power 

 gears and their teeth being an especially valuable 

 one for the designer of machine tools. To the main 

 spindle and its design three chapters are assigned, 

 and every important feature in regard to their con- 

 struction is fully discussed, especially in regard to 

 frictional losses and the means for reducing them. 

 The feeding mechanism to the saddle, and reversing 

 mechanism for feed motions, are dealt with in a suc- 

 cession of chapters, in which a perfect store of in- 

 formation has been brought together; for a general- 

 purpose lathe, the authors state that four to six turn- 

 ing feeds meet all ordinary practical requirements ; 

 this section of the book is followed by that which 

 treats of the feeding mechanism on the saddle, a 

 special chapter being devoted to the problem of such 

 feeds in heavy lathes; all this section of the book is 

 well illustrated with reproductions of photographs of 

 complete lathes, and of working drawings, often fairly 

 fully dimensioned, of the particular part of the 

 mechanism under discussion. 



In chapter xxxiv. the application of the experimental 

 data obtained by the authors to the problem of feed 

 mechanism design is fully explained. The design of 

 saddles and rests, the loose headstock, and the lathe 

 bed are all discussed in detail, and in connection with 

 the lathe bed it is shown that the proper form to give 

 the section is the box or circular, the lathe beds of 



