April II, 1878] 



NATURE 



471 



of the compound sound are made to strike on the 

 membrane at different periods of their swings. 



For example, if the compound sound is formed of six 

 harmonics, the removal of the source of the sonorous 

 vibrations, from the membrane to a distance equal to \ 

 of a wave-length of the first harmonic, will remove the 

 second, third, fourth, fifth, and sixth harmonics to dis- 

 tances from the membrane equal respectively to \, |, 

 I, I4, and i^ wave-lengths. The consequence evidently 

 is, that the resultant wave-form is entirely changed by 

 this motion of the source of the sound, though the 

 sonorous sensation of the compound sound remains 

 unchanged. 



The above facts are readily proved experimentally by 

 sending a constant compound sound into the cone of 

 Konig' s apparatus, while we gradually lengthen the tube 

 between the cone and the membrane next to the flame. 

 This is best done by the intervention of one tube sliding 



in another, like a trombone. These experiments I have 

 recently made with entire success, and they explain the 

 discussions which have arisen between different observers 

 as to the composition of vocal and other composite 

 sound, as analysed by means of Konig' s vibrating flames. 



These facts also show how futile it is for any one to 

 hope to be able to read the impressions and traces of 

 phonographs, for these traces will vary, not alone with 

 the quality of the voices, but also with the differently- 

 related times of starting of the harmonics of these voices, 

 and with the different relative intensities of these 

 harmonics. 



It is necessary to give to the cylinder a very regular 

 motion of rotation while it receives and reproduces the 

 vibrations made in singing ; for even slight irregularities 

 in the velocity of the cylinder destroy the accuracy of the 

 musical intervals; and cause the phonograph to sing 

 falsetto. Even the reproducing of speech is greatly 



^ • •• «» 



/^^VU^^VL^VU^^' 



Fig. 3. 



improved by rotating the cylinder by mechanism which 

 gives it uniformity of motion. If you make the machine 

 talk by giving it a more rapid rotation than it had when 

 you spoke to it, the pitch of its voice is raised ; and by 

 varying the velocity of the cylinder the machine may be 

 made to speak the same sentence in a very bass voice, or 

 in a voice of a pitch so high that its sounds are really 

 elfish and entirely unnatural. 



Recent experiments seem to show that the nearer the 

 diaphragm A approaches to the construction of the drum- 

 skin of the human ear by "damping" it, as the hammer- 

 bone does the latter, the better does it record and repeat 

 the sonorous vibrations ; for the motion of a membrane 

 thus damped is ruled alone by the aerial vibrations falling 

 on it. 



Mr. Edison has just sent me the following notes of the 

 results of recent experirhents : — 



" That the size of the hole through which you speak has 

 a great deal to do with the articulation. When words are 



spoken against the whole diaphragm, the hissing sounds, 

 as in shall, fleece, last, are lost ; whereas, by the use of a 

 small hole provided with sharp edges, these words are 

 reinforced and recorded. Also, teeth aroimd the edge of 

 a slot, instead of a round hole, give the hissing consonants 

 clearer. 



"That the best reading is obtained when the mouth- 

 piece, B F B (Fig. 2), is covered with several thicknesses 

 of cloth, so that the snapping noise on the foil is rendered 

 less audible. 



" I send you a sheet of copper-foil upon which I made 

 records in Ansonia, Connecticut, that could be read 275 

 feet in the open air, and perhaps farther, if it had been 

 tried." 



Mr. Edison also states that impressions of sonorous 

 vibrations have been made on a cylinder of soft Norway 

 iron, and from these impressions have been reproduced the 

 sonorous vibrations which made them. 



Alfred M. Mayer 



THE OLD RED SANDSTONE OF WESTERN 

 EUROPE"- 



Part I. 



IN a historical introduction the author gives an outline 

 of the progress of research into the history of the 

 Old Red Sandstone of the British Area. This system is 

 at present regarded as composed of three sub-divisions. 

 Lower, Middle, and Upper, each characterised by a 

 distinct suite of organic remains. From the absence of 

 unequivocally marine fossils and from lithological charac- 

 ters, it has been inferred by Mr. Godwin Austen, Prof. 

 Ramsay, Prof. Rupert Jones, as well as other observers, 

 and is now very generally admitted that the Old Red 

 Sandstone, as distinguished from the " Devonian " 

 rocks, probably originated in inland sheets of water. 

 The object of the present memoir was to endeavour 



» Abstract of paper by Prof. Geikie, F.R.S., read before the Royal 

 ociety o£ Edinburgh on April i, 1878. 



to trace out in that geological system of deposits the 

 changes of physical geography which took place over 

 Western Europe during the interval between the close 

 of the Upper Silurian and the beginning of the 

 Carboniferous period. 



After a sketch of the probable conditions of the region 

 previous to the commencement of the Old Red Sand- 

 stone, the author proceeds to show how the shallow- 

 ing Silurian sea was converted here and there into salinas 

 or inland seas, by a series of subterranean movements 

 which have left their indelible traces upon the upturned 

 Silurian rocks. He divides his memoir into two parts, 

 the first dealing with the Lower and the second with the 

 Upper Old Red Sandstone. The present paper deals 

 only with a portion of the first of these sections. It 

 traces out the limits of the different basins in which the 

 Old Red Sandstone of the British Islands were deposited, 

 and for the sake of convenience as well as briefness of 

 reference, proposes short geographical names for these 

 basins, which are arranged as follows : — 



