December 5, 1895] 



NATURE 



101 



r 



metallurgical processes by diagrammatic schemes such 

 as the author has" adopted ; see p. 198, for instance. 

 The one given for the blast furnace (p. no) is certainly 

 instructive. 



The illustrations, of which there are nearly one hundred, 

 are clear, but some of them are very old friends, while 

 others are perspective drawings ; and for a book like 

 this, the reviewer would have preferred to see sugges- 

 tive outlines and sketches, which the student could have 

 transferred to his note-book with a few strokes of the 

 pencil. W. R.-A. 



OUR BOOK SHELF. 

 Milky its Nature and Composition; a Handbook on the 



Chemistry and Bacteriology of Milk, Butter, and 



Cheese. By C. M. Aikman, M.A., D.Sc. Crown 8vo. 



Pp. 173. (London : Adam and Charles Black, 1895.) 

 The design of this little work is to give a short, popular 

 statement of the more important facts concerning the 

 chemistry and bacteriology of milk ; and Dr. Aikman has 

 succeeded admirably. A great deal of most valuable 

 information is conveyed in a simple and eminently read- 

 able form, and it is a volume which is not only suitable 

 for students in our recently started dairy-schools, but 

 might well find a place in the library of any country- 

 house. The general public is only very slowly awaken- 

 ing to the dangers which surround the consumption of 

 dairy produce, and it requires the pressure of enlightened 

 public opinion to produce the requisite reforms in the 

 hygienic management of dairies. Dr. Aikman's volume, 

 together with Dr. Freudenreich's " Bacteria in their 

 relation to the Dairy," recently reviewed in these 

 columns, should help a great deal in bringing about such 

 reforms, which are not only of hygienic but of com- 

 mercial importance to this country. In the section on 

 the pasteurisation of milk. Dr. Aikman has overlooked 

 an important fact, upon which the subsequent keeping 

 power of such milk so largely depends, i.e. the immediate 

 chilling of the milk after pasteurisation to a temperature 

 below the point most favourable for germination. We 

 think, in view of the recent valuable experiments, made 

 in America and elsewhere, on the production of pas- 

 teurised milk on a commercial scale, and the importance 

 of our adoption of a practice which has already gained 

 considerable ground on the continent. Dr. Aikman might 

 with advantage have entered more fully into this branch 

 of the subject. Doubtless in a second edition Dr. 

 Aikman will also expand somewhat the part devoted to 

 cheese, and include some of the important and interest- 

 ing results obtained by Bondzynski on the chemical 

 composition of some varieties of cheese, published in the 

 Landw. Jahrbuch der Schweiz last year. The illustra- 

 tions accompanying the text are carefully chosen and 

 well executed. 

 Elementary Physics. By John Henderson, B.Sc. (Edin.). 



Pp. 128. (London : Longmans, Green, and Co., 1895.) 

 It maybe well to remark at once that this is not a text- 

 book of physics, but the first volume of a series of manuals 

 designed solely for use in physical and electrical engineer- 

 ing laboratories. The present book is a general introduc- 

 tion to practical work in physics, and future volumes will 

 be devoted to more advanced experiments. Altogether, 

 eighty experiments are described, and are arranged in 

 sections having the following succession : general physics, 

 magnetism, electricity, heat, light, and sound. No 

 serious attempt seems to have been made to connect the 

 experiments in any particular order, so that, with few 

 exceptions, they are independent of one another. A 

 slight knowledge of physics is necessary before the 

 student can understand and carry out the course of work 

 described. This information may, however, be obtained 



NO. 1362, VOL. 53] 



from lectures given concurrently with the laboratory 

 work, though the order of the practical course is not 

 what most teachers follow in their lectures. 



The experiments can be performed without any very 

 elaborate apparatus, and we have no hesitation in saying 

 that the student who works through them will by so doing 

 obtain a sound knowledge of many important physical 

 laws. The knowledge thus gained by direct observation 

 is far and away better and deeper than that obtained by 

 reading text-books. 



Practical Trigonometry. By H. Adams, M.LM.E.. 



(London : Whittaker and Co., 1896.) 

 The author of this small book is careful to point out 

 that it is not a text-book ; but it will be found useful to- 

 practical men, in enabling them to undertake the perusal 

 of other than elementary works where a knowledge of 

 trigonometry is essential. 



The book is so arranged as to gradually disperse the 

 difficulties to beginners in trigonometry, and it cannot 

 but prove an incentive to further study. As an aide- 

 memoire, however, the absence of proofs, to secure 

 brevity, will diminish its value for examinations where 

 trigonometry is a special subject. W. S. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. "l 



Remarkable Sounds. 



With reference to Mr. McKenny Hughes' letter on this sub- 

 ject, which appears in your issue of the 14th ult., and to his 

 suggestion that it " would be of great help if we would get some- 

 exact data as to the distance at which the sounds of great guns, 

 of blasting, or of waves, can be proved to have been heard," I 

 would ask permission to be allowed to cite my experience on 

 the north coast of Spain at the fishing village of Comillas, about 

 twenty-four miles west of Santander. The bay which eives 

 rise to the port is relatively small, and of inconsiderable depth 

 inland ; the south-east part of it is limited shoreways by cliffs of 

 limestone, which rise to a height of about 120 feet, and some- 

 what overhanging the base or water-line. When the ground- 

 swell — so characteristic of the Bay of Biscay — comes in to this 

 bay, the breakers are very remarkable, and dangerous for small 

 fishing-boats, being relatively high, and succeeding one another 

 with great regularity. They break against the cliff mentioned 

 with a thundering noise, and such that I have frequently heard 

 them at eight miles' distance inland, although high and uneven 

 ground lay between me and the coast, and the weather was 

 relatively calm, so that the sound could hardly be favoured in its 

 transmission by the wind. In stormy weather, and when the 

 weather has been bad seaward, then the waves are even more 

 terrible, and the sound heard still farther away. 



Dublin, November 27. J. P. O'REILLY. , 



It is a pleasure to me to see Prof. Darwin's note on curious 

 sounds, in Nature for October 31 , since I have often been puzzled 

 by what is obviously precisely the same phenomenon along the 

 Bay of Fundy coast of New Brunswick, particularly about 

 Passamaquoddy Bay, where I have been a great deal in the 

 summer. Locally it is explained as the reports of the guns of 

 Indians shooting porpoises off the islands of Campobello and 

 Grand Manan ; but, for several reasons, I never believed this : 

 in fact, I have always been sure it must be due to some other 

 ! cause, though I could think of no explanation. It is heard most 

 often in summer, in rather still and warm weather, on those days, 

 when the heat-haze hovers upon the ocean, and appears to come 

 from seaward. W. F. Gano.ng. 



Smith College, Northampton, Mass., U.S.A. 



The " humming in the air," to which Mr. Tomlinson calls- 

 attention in your last number, is noticed in White's *' Selborne." 

 " There is a natural occurrence to be met with upon the 



