6o2 



NA TURE 



[October 19, 1905 



with some simple mechanical contrivances such as 

 the wedge, screw, lever, and pulley ; another on 

 simple harmonic motion, in which the pendulum is 

 rather fully dealt with ; and then follows a chapter 

 devoted to the mechanics of fluids, and comprising an 

 examination of the stability of floating bodies. The 

 book concludes with a chapter on units and 

 dimensions. 



Sets of examples arc given, the numerical answers 

 being collected at the end of the volume. Specimens 

 of recent intermediate science examination papers of 

 University College in connection with the Universitv 

 of London are appended. Some will regret that the 

 author does not assume a slight acquaintance with the 

 Calculus such as must be possessed by most readers 

 of the book. But taken altogether the subject is 

 dealt with very thoroughly, and developed naturallv 

 and logically, and the book deserves a wide circula- 

 tion. 



-l/f/57r 0¥ SIXGJXG-HIKDS. 

 field Book of Wild Birds and their Music. Bv F. 



Schuyler Mathews. Pj). xxxv-(-26.'. (New York 



and London : G. P. Putnam's Sons, 1904.) Price 



2 dollars. 

 HTHLS is a very pretty little book, with m.inv charni- 

 -L ing illustrations of .American singing-birds, and 

 numerous attempts to represent their songs in our 

 musical notation. It would seem as if the songs of 

 .Vmerican birds lent themselves more readilv "than 

 those of our European species to such notation, for 

 this is by no means the first attempt of this kind 

 which has recently been made on the other side of 

 the water. The present reviewer is under the dis- 

 advantage of not having heard these birds in tlicir 

 native land, and is quite ready to believe tlinl Mr. 

 Mathews's musical notations mav give nn .American 

 some vague idea of what his birds sing; at the same 

 time, as one whose knowledge of music is even older 

 than his knowledge of birds, he must emphaticallv 

 express a hope that British ornithologists will not 

 imitate their American brethren in trying to render 

 our familiar songs on this system. Our music is a 

 highly artificial product, subject to strict limitations 

 w^hich have gradually been placed upon it as the art 

 has developed in the course of many centuries; and 

 to attempt to catch and (so to speak) to tame the 

 songs of wild birds, bringing them forcibly under 

 conditions which entirely deprive them of their natural 

 freedom in regard to pitch, scale, time, and rhythm, 

 is in almost all cases to do them cruel violence. A 

 very few of our birds — the cuckoo, for example, and 

 the song-thrush — have vocal utterances which can be 

 expressed on our musical scale ; but by far the greater 

 number can only be represented in the amusing way 

 in which Mr. Mathews has noted the song of the 

 bobolink on pp. 50 and 51— by a cloudy jumble of 

 notes and lines above the stave, which suggests a 

 llute-player gone mad. 



The sentence which he lias prefixed to this curious 

 bit of notation really explains his object and method, 

 and forbids us to take him too scientifically. He 

 says, " If one prefers not to interpret bird-music, 

 but to take it from Nature exactly as it comes, this 

 NO. 1877, VOL. 72'j 



bit that follows may prove acceptable." What he 

 has reailv been trying to do, it seems, is to interpret 

 bird-music, by which he means that he has listened 

 to it with a musical mind, and has gained from it 

 certain musical impressions, which he again interprets 

 to us in the language of our musical art, not only in 

 the form of melody confined in the fetters of our 

 musical scale, but in many cases enriched with 

 ingenious accompanving harmonies. The reader will 

 find a good illustration of this method in the treat- 

 ment of the song of the American song-sparrow, 

 pp. 110 foil. It is the method pursued by all who 

 seriouslv attempt to transfer the notes of birds to 

 music-paper, though it may- be doubted whether they 

 would all acknowledge this as frankly as Mr. 

 Mathews. It follows that our knowledge of bird- 

 music is not really increased by these efforts, charm- 

 ing and interesting as they often are to the musician ; 

 for what is put upon paper is not the song of the 

 bird, but an interpretation of it by an artistic inind. 

 Taken in this light, this little book may give much 

 pleasure, and may add a good deal to our knowledge 

 of some delightful .\merican songsters. 



U". \\\ F. 



OUR BOOK SHELF. 

 Stiidicn iieber Hautelektricitiit und Hautmagnei- 



ismus des Meiischen. By Dr. Erik Harnack. Pp. 



65. (Jena : Gustav Fischer, 1905.) Price 1.60 marks. 

 The author takes a pocket-compass, about the size of 

 a lady's watch, with metal case and watch-glass top, 

 and having placed it on a level surface lightly rubs the 

 g'lass with the tip of his finger. The needle is imme- 

 diately deflected from the magne'ic meridian, remain- 

 ing so for a minute or more, and then returning to 

 its original position. That magnetism has nothing 

 to do with it is shown by the fact that the same 

 phenomenon occurs when for the magnet there is 

 substituted a needle cf nickel, platinum, zinc, bis- 

 muth, or ivory, although the absence in such cases of 

 a directive force makes it more difficult to observe. 

 Static charges, apparently much stronger, are with- 

 out efl^ect. Some people can influence the needle 

 much more than others, and the author's power is 

 not always equally strong. 



Quantitative experiments were undertaken bv the 

 author to measure the E.M.F. induced bv rubbing a 

 glass plate of the same size and shape in the same 

 manner. Using a Braun electrometer gniduated up 

 to 1500 volts, the maximum value obtained b\' him 

 was 1300 volts. It seems evident that a strong 

 electric charge is developed on a part of the glass sur- 

 face by the friction of the finger upon it, and that the 

 needle being free to move, and, moreover, in metallic 

 connection with the case, is attracted by the charged 

 surface. 



This is not disputed bv the author, his contention 

 being that the magnitude of the effect is out of all 

 proportion to the force expended, and that, there- 

 fore, it is not due to physical but to physiological 

 causes set in action by the slight friction of the finger- 

 tips. In the present writer's opinion this contention 

 is certainly not substantiated. The total energv of the 

 charge of a condenser composed of a compass-needle 

 and a square centimetre or so of glass with a P.D. 

 of a thousand or, for that matter, of ten thousand 

 volts is trifling, and since the work actuallv done 

 consists in the mere turning of the needle through 

 C)0°, one is driven to ask whether if a cocoon fibre 

 were attached to the end of the needle and to the 



