182 ANNUAL OF SCIENTIFIC DISCOVERY. 



best chance of attaining the general assent of contemporary musicians. 

 Though higher than the pitch of 51:2, the Philharmonic pitch, or the diapason 

 normal, the Stuttgard pitch is but a few vibrations higher than the last two 

 of these, one of which experience has proved to be a good pitch for instru- 

 mental music. It is a quarter of a tone below the present pitch, by general 

 consent voted intolerably high. Its adoption would involve little, if any, 

 inconvenience or pecuniary loss to instrumental performers or makers of 

 musical instruments. It would, therefore, be likely to meet the support of 

 the majority of those interested in the question of pitch. 



INTENSIFICATION OF SOUND: THE PHONOSCOPE AND HYDRO- 

 PHONE. 



Dr. Scott Alison has read to the Royal Society a paper "On the Intensifica- 

 tion of Sound through Solid Bodies by the interposition of water between 

 them and the distal extremities of Hearing-Tubes." The author gives an ac- 

 count of various experiments which he has recently made on sounds proceed- 

 ing through solid bodies. He has found that sounds which are faint, when 

 heard by a hearing-tube applied directly to solid sounding bodies, become 

 augmented when water is interposed between these bodies and the distal 

 extremity of the hearing-tube. He has been able, by the employment of 

 water, to hear the sound of a solid body, such as a table, which without 

 this medium has been inaudible. Experiments have been made upon water 

 in various amounts and in different conditions. Thus a very thin layer, a 

 mere ring round the edge of the hearing-tube, masses of water in larger or 

 smaller vessels, and a bag of water, have been employed. The results have 

 been the same as regards augmentation. The degree of augmentation was 

 greatest when the hearing-tube was immersed freely in water. In experi- 

 menting upon water in vessels, it was found necessary to close the extremity 

 of the tube to be immersed, by tying over it a piece of bladder or thin India- 

 rubber; for the entrance of water into the interior interfered greatly with 

 the augmentation. 



The effect of water in augmenting sound is materially reduced if even a 

 small amount of solid material be interposed between the water employed 

 and the mouth of the hearing-tube. A piece of wood, not much thicker 

 than a paper-cutter, materially interferes with the augmenting power of 

 water. The augmentation of sound thus obtained by water seems to be due 

 to the complete fitting of the liquid on the solid body, and also round the 

 mouth of the hearing-tube, whereby the column of air is thoroughly en- 

 closed; also to the less impediment to the vibrations of the instrument when 

 held in contact with water than when held in contact with a solid body, the 

 water yielding in a greater degree than a solid. 



The mode of judging of the augmentation was twofold: first, one sensa- 

 tion was compared with another perceived by the same ear, the one sensa- 

 tion following immediately upon the other; second, the differential stetho- 

 phone was employed, by which two impressions are simultaneously made 

 upon the two ears; in which case, if one impression be materially greater 

 than the other, sound is perceived in that ear only on which the greater 

 impression is made. To obtain the advantage of the differential stetho- 

 phone, or " Phonoscope," as it might here perhaps be more correctly desig- 

 nated, when sounds at some distance from the ear were being examined, its 

 length was increased by the addition of long tubes of India-rubber. 



