I/O 



NATURE 



[June 20, 1895 



say that this was a mistake, and that the fact has now- 

 long been recognised that many persons are unable to 

 distinguish red and green, though the true physiological 

 explanation is still unknown. 



We must now turn to a brief consideration of the chief 

 subject of Ualtons scientific investigations. In connection 

 with the histor>- of the evolution of the atomic theorj', 

 Sir Henrj- Roscoe has been so fortunate as to make an 

 interesting discover)-. .Among the " Dalton Papers " in 

 the possession of the Manchester Literar>- and Philo- 

 sophical Society, he has found the manuscript notes pre- 

 pared by Dalton for the course of lectures delivered at 

 the Royal Institution in the winter of 1S09-10. In these 

 notes he gives an account of the train of thought which 

 led him to adopt the atomic hypothesis for the explanation 

 of chemical phenomena. Contrary to the commonly re- 

 ceived account, which appears to ha%e originated with a 

 statement by Dr. Thomas Thomson in his " History- of 

 Chemistr)-," the atomic theor)- did not first occur to him 

 during his investigation of defiant gas and carburettcd 

 hydrogen gas. From the newly-discovered manuscript it 

 appears that Dalton's atomistic ideas arose in the course 

 of his study of the atmosphere, and in speculating as to 

 how a mixture of two or more clastic fluids could con- 

 stitute a homogeneous mass. .-V reader of his " Chemical 

 Philosophy " would perceive how thoroughly he was im- 

 bued with the Newtonian doctrine of particles, and in 

 Henn-'s " Life" this is clearly pointed out. 



By whatever process Dalton arrived at the adoption 

 of the atomic hypothesis, it is certain that his great 

 merit consisted in the application of a commonly 

 accepted (see " Chemical Philosophy," part i. p. 141), but 

 vaguely conceived, notion to the explanation of che- 

 mical phenomena. It was ''for the development of the 

 chemical theory of definite proportions, usually called the 

 "Atomic Theory," more especially, that he received the 

 first awarded Royal Medal in 1826. This is the point 

 upon which emphasis was particularly placed by the 

 president. Sir Humphry Davy, in presenting the medal. 



In the course of reading this little book we have met with 

 only one passage which seems to require correction. The 

 statemcnt'fp. 153) that Dalton's " great achievement was 

 that he was the first to introduce the idea of quantity into 

 chemistry" is not only erroneous but is inconsistent with 

 the writeHs own text, which on p. 161 contains a reference 

 to the names of Wenzel and Richter. 



We shall look forward with pleasure to the other 

 volumes of the series. W. A. T. 



HYDRAULIC AND OTHER POWERS. 



Hydraulic Motors, Turbines, and Pressure Enginct. By 

 (",. R. Bf)dmer, A.M.Inst.C.E. Pp. 540. (London: 

 Whiltakcr and Co., and George Bell and Sons, 1895.; 



Motive Powers and their Practical Selection. By 

 Reginald Bolton, .A.M.Inst.C.E. Pp. 250. (London 

 and New York : Longmans, Gtecn, and Co., 1895.) 



THE first of these works is a second and enlarged 

 edition of an excellent treatise on a subject seldom 

 dealt with in English text-books. The question of the 

 applicatitm of water-|)ower to useful purposes is becoming 

 more and more of importance, and the study of the 

 NO. 1338, VOL. 52] 



design and construction of the necessary machinery 

 naturally follows. Continental engineers are in advance 

 of us in this matter, they having long studied the problem 

 successfully. This difference, however, is rapidly dis- 

 appearing, and will be greatly assisted by the issue of 

 this work. 



The author has consulted to a greater or less extent 

 many works and publications, and appears to have 

 brought together much valuable information ; this, com- 

 bined with his own experience, makes the work an 

 important one. Historical matter has been purposely 

 avoided, as well as descriptions of obsolete forms of motors. 

 The author rather jocularly observes in his preface that 

 he is sure to be criticised, one way or the other, as to the 

 use of mathematics in his work. On the question of the 

 free use of mathematical methods we arc entirely of his 

 opinion, \iz. that formuUi; afford the readiest means of 

 accurately stating facts which in the simplest cases can 

 only be \erbally defined in elaborate phraseology. The 

 desciiption of the Niagara Falls installation is concise and 

 to the point. This installation is designed for utilising 

 10,200 cubic feet of water per second, with an available 

 head of 140 feet, which is equivalent, with an assumed 

 eflSciency of turbine of 75 per cent, to about 120,000 horse 

 power. The turbines were designed by Messrs. Faesch 

 and Piccard, of Geneva, and made by the I. P. Morris Com- 

 pany of Philadelphia ; each of these wheels is to develop 

 5000-horsc power, with a mean head of 136 feet. Other 

 interesting descriptions of recent installations arc added, 

 but we miss an account of the Worcester Electric Lighting 

 Station. This is to be regretted, because the installa- 

 tion is an example of a considerable application of 

 water-power under somewhat adxerse conditions. The 

 yround covered in this book, both theoretical and 

 practical, is of considerable extent. The author handles 

 the subject in a sensible manner, and arranges it in such 

 a way that the student can ha\e little diflficult\ in master- 

 ing it. For the engineer who looks for theoretical con- 

 siderations, there is ample food for reflection. The 

 descriptions of the general theor)' of various turbines are 

 remarkably clear, and are assisted by diagrams and 

 woodcuts. To those engaged in the design of turbines 

 the volume must be invaluable. 



Mr. Bolton's book on "Motive Powers" is of a very 

 diflfcrent nature, and belongs to that large number of text- 

 books written under the impression that a mere stringing 

 together of "facts, formuhe, and data " is of service to the 

 non-technical reader. The choice of a motor for any 

 particular duty, of course, largely depends on various 

 circumstances, and these must be considered by a quali- 

 fied engineer. It is questionable whether any amount of 

 study can qualify a non-technical man to niake a suitable 

 choice in such a matter. The book, however, contains a 

 large store of information suitable for engineers, and it is 

 arranged in a way that easy reference is possible, which is 

 an important consideration. The author \cxy properly falls 

 foul of the term " nominal horse-power," a useless term, 

 and one very likely to mislead. It is quite time that steam 

 and other engines were sold as representing tlie available 

 power, or " brake horse-power." Under the head of power 

 defined and compared, the author might \\:\\ii been more 

 explicit in his definition of the relation between "the 

 wall" and the "horse-power"; 746 watts are et|iial lo 



