June 14. 1906] 



NATURE 



149 



problem of conditioned observations, in which no set 

 of values can be assumed to satisfy approximately 

 the observation equations which does not exactly 

 satisfy some a priori conditions. 'Hiis problem may 

 not necessitate any fresh method of treatment, but the 

 applications are somewhat unusual, and, again, it is 

 of very great importance to know what is done in 

 actual practice. The authors have given us a valuable 

 treatise, prepared with care, and generally free from 

 errors. There is some confusion in the numbering of 

 the figures after p. 193, but this, if annoying, is of 

 less importance than any error in the formulae. 



W. E. P. 



OUR BOOK SHELF. 

 Modern Milling Machines. By Joseph G. Horner. 



Pp. ix + 304. (London : Crosby Lockwood and 



Son, 1906.) 124-. 6d. net. 

 A .MODERN .nachine shop in any large works would 

 be very incomplete indeed without a full comple- 

 ment of milling machines. The proportion of ii'i 

 class of machinery very largely depends upon the 

 class of work dealt with. For instance, in a sewing- 

 machine, cycle, or motor-car factory the milling 

 machine would predominate, being in many specialised 

 forms, each machine designed for some particular 

 function. On the other hand, in a general engineer- 

 ing establishment any milling machines installed 

 would be of the universal type, and capable of deal- 

 ing with many different operations, such as the uni- 

 versal machines made by Brown and Sharpe, of 

 U.S.A., and many others. 



It is only during recent years that milling 

 machinery has come prominently to the front, prin- 

 cipally due to the fact that designers of such machines 

 have grasped the fact that they must be made 

 of ample weight with large bearing and wearing 

 surfaces, so as to ensure steady running without 

 spring of the machine and consequent vibration. 

 Another very important consideration is the possi- 

 bility of obtaining suitable material for the cutters 

 used. The cost of making a milling cutter is in- 

 finitely more than the value of the cast steel used. 

 It is evident, therefore, that when once completed 

 the cutter should have a long life. This desideratum 

 has been rendered possible by the introduction of 

 high-speed tool steel, the results obtained being of 

 a most satisfactory nature, particularly those from 

 the " Air-hardened " steel manufactured by Edgar 

 Allen and Co., of Sheffield. The cost of the material, 

 therefore, is a secondary consideration. 



In the volume under notice the author describes 

 very fully many different types of machines, and 

 probably one of the best chapters is that dealing with 

 the design and manufacture of the cutters. The 

 power required very largely depends on the design 

 of cutter used, other things being equal ; to use a 

 cutter in any degree dull is also poor economy. 



Another valuable assistant to the milling machine 

 and its cutters is the introduction of special cutter 

 grinding machines, which, T believe, emanated from 

 the Brown and Sharpe Manufacturing Company. 

 Many of these machines are described and illus- 

 trated, the author having gone very fully into the 

 subject. This is as it should be, since a good cutter 

 is of the utmost importance in milling work. 



Chanter xi. is too short, though very interestinsr ; 

 it deals with the subject of feeds and speeds. On 

 these constant worries of a machine-shop manager 

 our author has much to say, and sensible advice to 

 give, and we cordially agree with him where he 



NO. 191 I. VOL. 74] 



points out how easy it is to get wonderful results 

 by means of a sharp tool running for short periods 

 by comparison with work done under ordinary shop 

 conditions. Such work, as a rule, does not pay. 



We can recommend this volume to all interested 

 in machine-shop practice. The machines dealt with 

 are of the latest type, and much useful inform.aion 

 will be found scattered through its pages. 



N. J. L. 



Lectures on the Method oj Science. Edited by T. B. 



Strong, Dean of Christ Church. Pp. viii-l-24g. 



(Oxford : Clarendon Press, 1906.) Price 7s. f>d. net. 

 TiiESR lectures formed i)art of a course on scientific 

 method delivered at the University Extension summer 

 meeting at Oxford last August. The discourses are 

 intended to illustrate the forms taken by scientific 

 method in various departments of research. Prof. 

 Case deals with scientific method as a mental oper- 

 ation ; Prof. Francis (iotch, F.R.S., treats of various 

 aspects of the method; Prof. C. S. Sherrington, 

 F.R.S., describes the scope and method of physiology; 

 the lecture by the late Prof. \\'eldon discusses inherit- 

 ance in animals and plants ; Dr. W. McDougah ex- 

 plains the psychophysical method; Dr. A. H. Fison 

 applies the method to the question of double !,tars, 

 Sir Richard Temple to the evolution of currency and 

 coinage, Prof. W. M. Flinders Petrie, F.R.S., to 

 archaeological evidence, and the Rev. Dr. Strong to 

 history. 



From the nature of the case, the arguments are 

 such as to appeal to persons of general culture rather 

 than to specialists. If Oxford were as energetic in 

 the prosecution of scientific research as she is in 

 popularising knowledge by means of extension lec- 

 tures, men of science would probably be disposed 

 to think her activities better and more suitably 

 directed. The omission of an index can never be 

 justified in the case of a scientific book, but that a 

 work devoted to scientific method should be deficient 

 in this respect is an irony which cannot be overlooked. 



The Secrets .of Dog-Feeding. By "Great Drne." 

 Pp. ix-l-58. (Southampton: Toogood and Sons, 

 1906.) 

 The mere fact that this little work has reached 

 its second edition within less than a year of the 

 date of its first appearance may be taken as a_ suffi- 

 cient guarantee that it has obtained the verdict of 

 approval from dog-owners, and is therefore a success. 

 The author is of opinion that the nature of the food 

 is a matter of prime importance in the case of valu- 

 able, highly-bred dogs, and one which too often 

 receives but insufficient attention on the part of their 

 masters. While advocating a mixed diet, he depre- 

 cates the use of green vegetables, which has of late 

 years come much into fashion amons; many dog- 

 owners; and he adds tha't to a dog which has been 

 kept largely upon farinaceous food the change to 

 a meat diet in later years will often produce highly 

 satisfactory results. The constituents of nearly all 

 the foods 'referred to are given, so that readers can 

 iuds-e for themselves as to their nutritious value. 

 ^ R. L. 



In My Garden. A Little Summer Book for Nature 

 Lovers. Pp. 72. (Wellingborough : The Laven- 

 der Press; London: Philip and Tacey, Ltd., 1906.) 

 Price IS. net. 

 This dainty little memorandum book, with its blank 

 pages for notes on experiments in gardening and 

 other observations of natural objects, will please_ all 

 students of country life. The well-selected quotations 

 and the hints on table decoration should appeal to a 

 wide circle of readers. 



