244 



NATURE 



[April 20, 191 1 



ably carry on the campaif^n of the German geoiogists 

 Uvc a more general understandiiifj of the earth. After 

 indicating that an oceanic and nuxlerately cold i limale, 

 rather than a contincntally extreme one, will provide 

 the conditions for an Ice a>,'e, the author appeals to 

 the scenic features of a country where glacrers have 

 worked their way. lie supports the view of the over- 

 deepcninjf of valleys by glaciers, .ind clearly points 

 out the effects of differences of pressure in different 

 regions of a complex ice-stream. Prof. Heim would 

 doubtless remark that the U-form indicated in the 

 picture of the Lauterbrunnen valley (p. 21) is obviously 

 due to taluses ; but little fault can be found with the 

 author's account of the variety of characteristic out- 

 lines traceable in all regions that have undergone an 

 Ice age. 



The etching out of cirques primarily by frost-action, 

 as on the margin of melting snow, rather than by 

 the glaciers that ultimately occupy 

 them, is surely sustainable, in spite 

 of what is said on p. 37; but we 

 agree with the author that the 

 erosive |X)wer of glaciers has been 

 very freely underrated. The study 

 of moraines and outwashed mate- 

 rials is used to explain the 

 phenomena of the North German 

 plain, and the lost freshwater lakes 

 of Bolivia are introduced as 

 evidence of the universality of the 

 Ice age. New interest is aroused 

 by the account of pre-Glacial and 

 Glacial man with which the book 

 concludes. G. A, J, C. 



piece of music — indeed, by an effort of attention, I have 



so trair'-' ■•" *'"■' ' ■ '" hear one without h'--"-;n < ih- 



othfT. 11 thff *ar there is a 



f<,r thf: - of high pitch as di- 



ordinary musical tcuieji. It occurred to mc that by < 

 the sounds to pass through numerous narrow ch.' 

 freely rommuniratind with each other, the noise-»ouno- 

 presumably raused by short waves of high pitch, mij^t b>- 

 damp«'d off by interference, while lh<; longer waves, rr..-r,.. 

 sponding to musical tones, might pass through un;i' 

 except as regards loss of energy from friction. My pi , 

 was attained by filling a segment of the tin tube, say, from 

 4 to 8 fret in length, with a mixture of hard peas and 

 beans, corrugated by age or drying. The experimer. 

 ceeded. The friction noises were damped down, wli 

 musical tones, although rather " dulU^d " in quality, ;..... 

 is to say they lacked brilliancy, were purer, and, to my 

 ear, much more natural. 



Other substances were tried— -glass balls, marbles, small 

 fir cones, gravel, shreds of tin — but the best effect was 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself re- 

 sponsible for opinions expressed by 

 his correspondents. Neither can he 

 undertake to return, or to correspond 

 with the writers of, rejected manu- 

 scripts intended for this or any other 

 part of Nature. No notice is taken 

 of anonymous communications.] 



Further Experiments with the Gramophone. 



In Nature of April 15 and October 21, 1909, 1 described 

 various experiments with the gramophone. Since then 

 I have made many efforts to get rid of the hissing and 

 grating noises that detract so much from the instrument 

 as a reproducer of musical sounds, and at last I have had 

 an encouraging measure of success. The gramophone, as 

 will be seen in the accompanying figure, is enclosed in a 

 wooden cloth-lined box, and a tube passes tightly through 

 a hole in the wall of the box from the end of the taper 

 arm that carries the sound box of the instrument. When 

 the sound box is tightly closed by raising and locking the front 

 lid, as seen in the figure, the sounds of the machinery, and 

 also the vibrations from the free side of the diaphragm of 

 the sound box, are completely damped off. The noises, 

 caused by the friction of the needle point on the hard disc 

 of the record, pass, of course, along with the musical 

 sounds, through the taper arm to the tube that escapes 

 from the box. This tube is suitably connected with 

 lengths of tin tubing, ij inch in diameter, and the sounds 

 are thus conveyed through as many feet of tubing as may 

 be found necessary. I have found the most efficient length 

 of the entire tube, until it reaches the horn or resonator 

 (the attachment of which is seen in the figure), to be, say, 

 .<;4 feet. The effect of the long tube, while empty, is to 

 increase the volume of the tones, but, of course, the noises 

 are also intensified. 



I have always been struck by the fact that the friction 

 noises seem to be quite separate and distinct from the 

 musical tones, either when a voice is singing with an 

 accompaniment, or during the reproduction of an orchestral 



NO. 2164, VOL. 86] 



Gramophone arranged to get rid of friction no'uei. 



obtained with the peas. Brilliancy was obtained by using, 

 as suggested and made by Mr. Ernest De la Rue (who 

 has been much interested in these researches), zinc tubes 

 filled with fragments of corrugated zinc, and the use of 

 these has been protected by patent by Mr. De la Rue. 

 By a combination of the zinc fragments with the peas and 

 beans, I get delightful effects, so that the gramophone- 

 music is so immensely improved that I cannot listen with 

 any pleasure to the " naked " gramophone sounds, as 

 the attention is not now disturbed by the " frying-pan " 

 noises. 



.As listening to music so reproduced is a kind of auditorv 

 illusion, any contrivance that will heighten the illusion 

 may be expected to give more pleasure if the illusion is 

 of the right kind. Usually one feels a sense of unreality 

 in the music apparently rising from the bottom of the 

 " horn," more especially in listening to a human voice. 

 To get rid of this, I angle the horn, as shown in the 

 figure, so as to reflect the sound waves from a tin reflector 

 (parabolic in character) so placed as to send the sounds to 

 the other side of the room. One then ceases, while listen- 

 ing, to think of either the gramophone or the horn, as 

 the sounds come from the reflector, and the effect is much 

 more real and natural. 



I believe the application of this method of " acoustical 

 filtration " may be applied by ingenious mechanics in such 

 a way as to do away with the necessity of building up 

 such an array of tubes as is seen in the figure. The 

 method enables one, in a room of moderate size, to listen 

 to pure music. One cannot help obser\ing how it mellows 

 a voice that, heard in the ordinary wav, sounds harsh 



