EDITOR'S TABLE. 



625 



they yield ; plants, for example, being 

 poor witnesses in such a case, and the 

 higher vertebrates the best. Geologists 

 will be interested in the researches of 

 the author, the results of which are 

 also given, into the origin and succes- 

 sion of the Tertiary fresh-water lakes 

 of the Rocky Mountain region ; a sub- 

 ject upon which but little accurate in- 

 formation has been hitherto attainable. 

 The portion of the paper printed in the 

 present Monthly includes the fishes, 

 amphibians, reptiles, and birds; and 

 the second part will be devoted to the 

 mammals, which will be discussed more 

 in detail. Prof. Marsh has kindly pre- 

 pared for us a geological section of the 

 earth's crust, revised so as to illustrate 

 the present aspect of the subject of the 

 introduction and succession of verte- 

 brate life on this continent, and which 

 the reader will find valuable for refer- 

 ence in studying the address. 



SOME TEACHINGS OF TEE TELE- 

 PHONE. 



We commend to those who persist in 

 ventilating the ancient prejudice against 

 the material medium of which all things 

 around us are constituted, as " dead 

 matter," " gross matter," " brute mat- 

 ter," etc., a little meditation on the 

 remarkable powers manifested by the 

 telephone. 



In another part of the Monthly 

 will be found an excellent explanation 

 of the mechanism and mode of work- 

 ing of this remarkable contrivance. 

 But, to appreciate its deeper meaning, 

 we must recall some of the characteris- 

 tics of sound and the conditions of the 

 production of voice. The brain, the 

 spinal centres, the nerves, and the mus- 

 cles, have all to be coordinated in that 

 expulsion of air through the apparatus 

 of speech which results in the utterance 

 of words. The vocal cords are thrown 

 into vibration by the air-current which 

 sets up wave-motions that are trans- 

 mitted in all directions. To appreciate 



what here goes on in this light, invisi- 

 ble medium, we must strive to keep in 

 mind the behavior of the air-particles. 

 In the propagation of sound, a stream 

 of thrills is shot out from its source, at 

 the rate of about eleven hundred feet 

 per second, and the series of air-waves 

 is simply a succession of condensations 

 and rarefactions of the elastic medium, 

 in which the aerial particles successive- 

 ly take up and pass on the motions of 

 the original impulse. According to the 

 extent and complexity of these molecu- 

 lar motions is the intensity and quality 

 of the noise. The size of the waves 

 varies with the pitch of the sound ; the 

 first A of the bass in a piano producing 

 air-waves about forty feet in length, 

 while the waves of the last A of the 

 treble are not quite four inches long. 

 But these sound-waves are far more 

 complex than at first seems, so that 

 the motion of the air-particles involves 

 something else than a mere backward- 

 and-forward movement. A stretched 

 string, vibrating its whole length, gives 

 its fundamental tone, but while it thus 

 swings as a whole, its different parts 

 are thrown into separate and quicker 

 vibrations, which are executed in har- 

 monic ratio 2, 3, 4, 5, 6, 7, or 8 times 

 during the vibration of the whole string. 

 These over-vibrations produce what are 

 called overtones, which are, so to speak, 

 drowned in the fundamental note, but 

 which, nevertheless, serve to give it a 

 peculiar character. It is thus that 

 sounds from all sources acquire distin- 

 guishing marks, by which they are iden- 

 tified. It is by the effects of these frills, 

 or fringes, of the larger waves, that dif- 

 ferent musical instruments, and differ- 

 ent human voices, are distinguished 

 from each other. The infinite varieties 

 of sound are thus due to the subtile ca- 

 pacity of complex motion possessed by 

 the air-particles. They always move 

 exactly in the same way in the produc- 

 tion of the same effects, and differently 

 in yielding different effects. If we could 

 see the dance of the air-particles when 



VOL. XII. 40 



