146 SCIENCE PROGRESS 



read ; a book which will appeal to the general reader by its simplicity and 

 clarity as much as it will those familiar with its subject matter by the many 

 curious facts that it contains. The lectures were intended for a juvenile 

 audience, and very rarely indeed does the treatment pass beyond their 

 understanding, a fact which, in itself, is no small triumph for the author. 

 The whole production, with its attractive cover and little pencil insets by 

 Miss Audrey Weber, strikes a new note for a work on a physical subject ; 

 it appears, indeed, to have been modelled on the books of Dr. Seton-Thompson 

 and other writers of animal biographies. 



The first two chapters contain an account of the elements of the subject, 

 i.e. a study of wave motion in general and of the vibrations which produce 

 sound in particular. These rather forbidding matters are dealt with in a 

 most interesting manner by frequent appeals to the evidence of the ripple 

 tank, and by many ingenious and strildng experiments as, for example, the 

 five springs, maintained in vibration by an electric current, which render 

 visible the mode of vibration of the air in closed and open pipes. The rest 

 of the book is divided by a happy inspiration into chapters on the charac- 

 teristic sounds of the town, the country, the sea, and of war ; the sub- 

 ject-matter under each heading serving as a means of introducing many 

 fundamental phenomena in novel dress. Thus, among the sounds of the town 

 is the familiar " plop " of water as it drips into a bath or bucket. Sir Richard 

 Paget has measured up the cavities in the water made by the falling drops 

 and constructed models of them in plasticine. The noise of the drops can 

 then be reproduced by blowing across the mouth of the model cavity so that 

 the source of this sound is made quite clear. Again, there is an account of 

 the novel phenomenon which underlies the use of the ocarina, namely, that 

 with similar vessels of the same size that which has the widest opening gives 

 the note of highest pitch. There is also, in this chapter, a discussion of 

 the Doppler effect, of architectural acoustics, and of singing flames whose 

 note is more familiar as the roar of the fire up the chimney. 



In the next chapter we are told of the sounds of the insects and of the 

 trees ; of the grasshopper's tambourine, of the cricket's bow, and of the 

 knockings of the " Death-watch " beetle. We learn the secrets of aeolian 

 tones and of the difference between the sounds made by the leaves of the 

 trees ; why the poplars rustle, and why the sound of the wind in a pine 

 wood is high-pitched and soft. The sea does not provide so many striking 

 examples, for its depths are silent and outside our experience ; but in the 

 fish we find the crudest form of ear, and the author traces for us the develop- 

 ment of this organ and tells us something of its amazing powers. The last 

 chapter on " Sounds in War " contains an account of some of the devices 

 used for the detection of submarines and for the location of guns and mining 

 galleries. It is remarkable that, while before 19 14 sound had been a par- 

 ticularly " pure " science, yet in the next five years almost everything that 

 had previously been discovered found some useful application. 



In conclusion, we can only advise those who have not yet placed this 

 book on their shelves to fill the gap at the earliest opportunity. 



D. O. W. 



Laboratory Projects in Physics. By Frederick F. Good, A.M., Instructor 

 in the School of Practical Arts, and in the School of Education, 

 Columbia University, New York City. [Pp. xiv + 267, with 104 

 figures.] (New York : Macmillan & Co., 1920. Price 9s. net.) 



Here is a course in practical physics of the every-day kind which has been 

 worked out to the smallest detail by the author for the use of beginners — both 

 boys and girls — in a modern " High School." It is not clear from the preface 

 that the course has actually been used in its entirety, but it is clearly of a 



