Sept. 23, 1880] 



NATURE 



50c 



rotation of the disk interrapted wliat was then an invisible beam, 

 which passed over a space of about twelve feet before it reached 

 the lens which finally concentrated it upon the selenium cell. A 

 faint but perfectly perceptible musical tone was heard from the 

 telephone connected \\ith the selenium. This could be inter- 

 rupted at w ill by placing the hand in the path of the invisible 

 beam. It would be premature, without further experiments, to 

 speculate too much concerning the nature of these invisible rays ; 

 but it is difficult to believe that they can be bent rays, as the 

 effect is produced through tn o sheets of hard rubber containing 

 between them a saturated solution of alum. Although effects 

 are produced as above shown by forms of radiant energy which 

 are invisible, we have named the apparatus for the production and 

 reproduction of sound in this way "the photophone," because 

 an ordinary beam of light contains the rays which are operative. 



It is a well-known fact that the molecular disturbance pro- 

 duced in a mass of iron by the magnetising influence of inter- 

 mittent electrical current can be observed as sound by placing 

 the ear in close contact with the iron. It occurred to us that 

 the molecular disturbance produced in crystalline selenium by 

 the action of an intermittent beam of light should be audible in 

 a similar manner without the aid of a telephone or battery. 

 Many experiments were made to verify this theory without 

 definite results. The anomalous behaviour of the hard i-ubber 

 screen suggested the thought of listening to it also. This ex- 

 periment was tried with extraordinary success. I Ijeld the sheet 

 in close contact with my ear, while a beam of intermittent light 

 was focussed upon it by a lens. A distinct musical note was 

 immediately heard. We found the effect intensified by arrang- 

 ing the sheet of hard rubber as a diaphragm, and listening 

 through a hearing-tube. We then tried the crystalline selenium 

 in the form of a thin disk, and obtained a similar, but less in- 

 . tense effect. The other substances which I enumerated at the 

 beginning of my address were now successively tried in the form 

 of thin disks, and sounds were obtained from all but carbon and 

 thin glass. We found hard rubber to produce a louder sound 

 than any other substance we tried, excepting antimony, and 

 paper, and mica to produce the weakest sounds. On the whole 

 we feel warranted in announcing as our conclusion that sounds 

 can be produced by the action of a variable light from sub- 

 stances of all kinds, when in the form of thin diaphragms. We 

 have heard from interrupted sunlight very perceptible musical 

 tones through tubes of ordinai-y vulcanised rubber, of brass, and 

 of wood. These were all the materials at hand in tubular form, 

 and we have had no opportunity since of extending these 

 observations to other substances. 



I am extremely glad that I have the opportunity of making the 

 first publication of these researches before a scientific society, for 

 it is from scientific men that my work of the last six years has 

 received its earliest and kindest recognition. I gratefully re- 

 member the encouragement which I received from the late IVof. 

 Henry at a time when the speaking telephone existed only in 

 theory. Indeed, it is greatly due to the stimulus of his appre- 

 ciation that the telephone became an accomplished fact. I can- 

 not state too highly also the advantage I-received in preliminary 

 experiments on sound vibrations in this building from Prof. 

 Cross, and near here from my valued friend Dr. Clarence J. 

 Blake. When the public were incredulous of the possibility of 

 electrical speech, the American Academy of Arts and Sciences, 

 the Philosophical Society of Washington, and the Essex Insti- 

 tute of Salem, recognised the reality of the results and honoured 

 me by their congratulations. The public interest, I think, was 

 first awakened by the judgment of the very eminent scientific 

 men before whom the telephone was exhibited in Philadelphia, 

 and by the address of Sir William Thomson before the British 

 Association for the Advancement of Science. 



At a later period, when even practical telegraphists con- 

 sidered the telephone as a mere scientific toy, Prof. JohnPeirce, 

 Prof. Eli W. Blake, Dr. Channing, Mr. Clarke, and Mr. Jones, 

 of Providence, Rhode Island, devoted themselves to a series of 

 experiments for the ■ purpose of assisting me in making the 

 telephone of practical utility ; and they communicated to me 

 from time to time the result of their experiments with a kindness 

 and generosity I can never forget. It is not only pleasant to 

 remember these, things, and to speak of them, but it is a duty 

 to repeat them, as they give a practical refutation to the] often 

 repeated stories of the blindness of scientific men to unaccredited 

 novelties, and of their jealousy of unknon-n inventors who dare 

 to enter the charmed circle of science. I trust that the scientific 

 favour which was so readily accorded to the telephone may be 

 pxtendcd bv y-u to this new claimant — the photophone. 



SCIENTIFIC SERIALS 



The Quarterly Journal of Microscopical Science, July, con- 

 tains— F. M. Balfour, on the structure and homologies of the 

 germinal layers of the embryo (with woodcuts), — On Hubrecht's 

 researches on the nervous system of nemertines (with a plate) 

 abstract of.— A. G. Bourne, on the structure of the nephridia of 

 the medicinal leech (with two plates).— Prof. Ray Lankester, 

 on intra-epithehal capillaries in the integument of the medicinal 

 leech (with a plate) ; and on the connective and vasifactive 

 tissues of the same (with two plates).— Dr. H. Gibbes, on the 

 use of the Wenham binocular with high powers. — On the 

 structure of the spermatozoon. — P. II. Carpenter, on some 

 disputed points in Echinoderm morphology. — Prof. Pouchet, on 

 the origin of the red-blood corpuscles (translated from the Revvc 

 Scientifique). — Prof. Ray Lankester, on Limnocodiuin so^werbii, a 

 new trachomedusa inhabiting fresh water (with woodcuts and 

 two plates) [for an abstract vide Nature, vol. xxii. p. 147]. — 

 Notes and memoranda. — Proceedings oi the Dublin Microscopical 

 Club for November and December, 1879. 



3 ' Reinie d' Antltropologie, tome iii. fascic. 3 (July). — Prof. J. 

 Delbos, of Nancy, gives a brief report of the discovery, made 

 in 1S69, of a number of human skeletons in the loam beds of 

 Bollwiller (Haut-Rhin). His paper, which describes the general 

 geognostic character of the soil in which these remains were 

 found, is followed by a detailed description, by Dr. Rene Col- 

 lignow, of each of the seven distinct skeletons that have been 

 recovered. Of these, five were a.lult males, two females, and 

 one a child of about seven. In general characteristics they 

 resemble the Cannstatt remains. — Dr. Bc'renger-Feraud, whose 

 position in Senegal as Medecin-en-chef de la Marine gave him 

 favourable opportunities of studying the habits of the natives, 

 has drawn up an interesting report of all that is known on the 

 spot in regard to the mysterious sect of the Simos, which exer- 

 cises an important influence on the tribes of the west coasts of 

 Africa, from Cape Vert as far as the Gabon settlements on the 

 equator. The Simo of these regions is the dreaded Mombo- 

 Yombo of other races. — Di-. Gustave Lagneau's paper, " De 

 quelques Dates reculees," is a scholarly dissertation on the com- 

 munity of race traceable in the Belga?, Galli, and Germani, and 

 on the evidence supplied in reference to the period of their 

 immigration into Keltic lands by the introduction of a dolicho- 

 cephalic character, in addition to the purely brachycephalic type 

 observable in the skulls of Keltic and Kimmerian races. In dis- 

 cussing the question of the occupation of Western Europe by 

 Iberians, M. Lagneau enters at length into the historical and 

 anthropological grounds for accepting the testimony of Plato 

 and others as to the defeat of those tribes by a powerful race, 

 the Atlanta;, and the existence of a great western continent, or 

 archipelago, the submerged Atlantis, from which the latter 

 peoples made their inroads on West Africa and West Europe. — 

 M. Martinet's enumeration of the prehistoric monuments of 

 Berry deserves special notice for the interesting information 

 it supplies in reference to the so-called " Mardelles," a kind of 

 conically shaped excavations, the purport of which has not been 

 determined, and which, although found elsenhere, as in Nor- 

 mandy, Provence, cite, is of exceptional frequejyjy in Berry, 

 where between 300 and 400 have been explored." In diameter 

 they vary from 20 to 100 metres, in depth from 50 centimetres 

 to S metres. Traces of ashes, calcined animal bones, and coarse 

 potsherds, with a few broken flints, have been found at the 

 bottom of these depressions, of which several are generally 

 ranged in a line near natural or artifically constructed caverns. 



yournal de Physique, August. — Experimental researches on 

 rotatory polarisation in gases, by M. H. Becquerel. — Magnetic 

 ro'atory power of liquids and of their vapours, by M. Bichat. — 

 Experiments on flames, by M. Neyreneuf. 



Journal of the Franklin Institute, August. — The limitations 

 of the steam-engine, by W. D. Marks. — Economical cut-off in 

 steam-engines, by S. W. Robinson. — The involute of the cir- 

 cumference of a circle, by J. J. Skinner. — Holman's new com- 

 pressorium and moist chamber, by J. A. Ryder. 



Rii'ista Scientifico-Induslriale, No. 15, August 15. — Periodic 

 spontaneous movement of the stamens of Rula bracteosa, D.C., 

 and of Smyrniiin rotundifolitim, by Dr. Macchiati. — Synthesis 

 of meteorological observations in Modica and .Syracuse on the 

 fall of meteoric powders, from the end of 1876 to April 16, 

 1880, by Prof. Lancetta. 



No. 16, August 31. — On type:; of rocks, by Prnf. de Stefani. 



