2IO 



NATURE 



[June 20, 1878 



portion of the sonorous wave in conipre sion from that in ex- 

 tension, the result is that we have a variation in the resistance of 

 the line. Now this variation in resistance depends upon the 

 compression and dilatation of the molecules. They depend upon 

 the tone of the voice, and the result is the resistance of the 

 current varies with its variation of pressure, and at the distant 

 end we have currents varying exactly as the voice varies, and 

 reproducing on the telephone all the effects which we have seen. 

 Hence follows the action of the microphone, and the action of 

 the transmitter is one which depends upon the variation produced 

 in bodies by the sonorous vibrations of the voice. As I am 

 now speaking at that telephone, all the molecules of that trans- 

 mitter are thrown into this elaborate series of CDmpressions and 

 dilatations. The current is varied ; it goes to the room below, and 

 is reproduced upon the telephone, as we have heard. Hence 

 the effect is due to the difference of presfure, as is proved by 

 using atmospheric pressure, and applying heat ; and any large 

 increase of pressure results in sound bemg reproduced. 



No one has ever been nearer a great discovery than Mr. 

 Edison. His telephone is based on the variation of resistance 

 due to pressure. He used carbon and finely divided matter, 

 but he worked on the idea that the difference in pressure was 

 produced by the vibrations of a diaphragm. Hcd he thrown 

 away his diaphragm he would have forestal'ed Prof. Hughes in 

 this respect, and found that the sonorous vibrations themselves 

 produced this difference of pressure. The great secret of Prof. 

 Hughes's discovery is that sonorous vibrations and electrical 

 waves are to a certain extent synonymou*. 



Now as to the uses to which this instrument is capable of 

 being applied. It has been applied to surgical purposes in the 

 form of the stethoscope. Though it does not show very 

 markedly the beats of the heart, because they are more 

 mechanical thumps than sonorous vibrations, yet it will show 

 the injection and ejection of air in the lungs, and for many other 

 surgical purposes it must become a valuable instrument. It 

 admits us to some of the mysteries of insect life, and by its 

 means we can hear sounds emitted by insects which have never 

 been heard before. Going further it has enabled the deaf to 

 hear ; deaf persons who never heard a telephone before have 

 been able to hear distinctly. It has enabled us to hear the 

 physical operation which goes on in the process of crystalliza- 

 tion of bodies and other things which before were wholly in- 

 audible ; and in fact it is impossible to say to what uses it may 

 not be put. 



It is rather remarkable that in an excellent paper read before 

 the American Electrical Society, the author, Mr. Pope, makes 

 these curious remarks : — 



" The most striking results are to be looked for in the direction 

 first pointed out by Mr. Gray, for the reason that if an effectual 

 method of controlling the resistance of the circuit by means of 

 atmospheric vibrations can be discovered, the source of power, 

 which in this case is the battery, may be augmented to any re- 

 quired extent. It is not to be denied that the problem thus 

 presented is one of exceeding mechanical difficulty, but there 

 is no reason to suppose that it may not be successfully solved. 

 It is to the development of this variety of the speaking telephone 

 rather than to that of the magneto instrument that inventors will 

 find it most advantageous to turn their attention, for I hazard 

 little in saying that the latter has already reached such a 

 surprising degree of efficiency, as to leave comparatively little 

 more to be done within the necessary limitations which have 

 been pointed out." 



Mr. Pope throws out what has been done with the exception 

 of the supposed mechanical difficulty, and that has been got 

 over by a halfpenny money-box. 



Now one very pleasing and gratifying circumstance attaches 

 to this discovery of Prof. Hughes : he has thrown it open to the 

 world, and by that means he has no doubt checked that species 

 of immorality — I don't know what else to call it— connected 

 with the infringement of the patent law, as regards the tele- 

 phor.e. He allows us all to manufacture microphones for our- 

 selves, Vut even he has been subjected to rather a peculiar inci- 

 dent. One impulsive and active gentleman who was present at 

 the Royal Society the other night when Prof. Hughes first 

 described his invention, went home and made himself a micro- 

 phone, wrote a description of it and sent it off post haste to 

 Paris. A short time afterwards Prof. Hughes himself with 

 great care prepared a paper to be read before the French 

 Academy, but to his great surprise he found that he had been 



forestalled, a description of his instrument had already appeared 

 in the Paris prints from the gentleman in question. 



There are lessons to be learnt from this discovery, and the 

 principal lesson is — we can all of us with the means at our 

 disposal cross-question nature and find out her secret?, and there 

 are many secrets which yet remain to be divulged. We learn 

 the wonderful connection which exists between all the physical 

 forces : heat, and light, and electricity, and magnetism, are all 

 CO -related, and it has come to this, that what boys have said in 

 joke has come to pass in earnest. We have been able to con- 

 vert electricity into light, and light into electricity. We are 

 now able tO' convert electricity into sound, and sound into 

 electricity, and thus we are enabled to see the thunder and to 

 hear the lightning. 



THE SCIENTIFIC AIMS AND ACHIEVE- 

 MENTS OF CHEMISTRY^ 



A/TORE than a generation has passed away since my predc 

 ^^ cesser in the chair of Chemistry, Prof. Bischof, who was 

 so full of merit in the domain of chemical geology, held the high 

 office which the friendly confidence of my colleagues has entrusted 

 to me for the ensuing university year. Since that time chemistry 

 has undergone important changes, and its position upon the 

 German high schools has also become an essentially different one. 



At that time a general discouragement had takei root 

 amongst the most eminent chemists. It was believed that all 

 speculation had to be dismissed from the field of chemistry, and 

 particularly that all atomistic considerations had to be discon- 

 tinued, because whole categories of facts could not be made to 

 agree either amongst each other, nor with the general theoretical 

 views of that time. 



At our high schools at that tima chemistry was only taught 

 from the chair ; very often by teachers who were essentially 

 appointed for other subjects. At most of the universities the 

 students could be admitted to practical work only by favour of 

 the teachers, and even Liebig's laboratory at Giessen, the first 

 of all educational laboratories, only just then received its interior 

 arrangement. 



How different now ! Well aware of its task and its aim?, 

 scientific chemistry, in close connection with physics, advances 

 slowly, it is true, but with self-reliance and a certain confidence. 



Each university has its special chair of chemistry, many indeed 

 have several. Richly furnished laboratories, and very often 

 luxurious edifices, are at the disposal of chemical students in 

 nearly all German universities, and the chemical lectures are the 

 best frequented ones almost everywhere. 



All this and also the circumstance that it is just a chemist who 

 is able to day, as a representative of the entire university, to speak 

 to the entire university from this place, proves, doubtless, that our 

 science is now generally recognised to the extent it merits. But 

 as on many sides it is over-estimated, it is yet more frequent, on 

 the other hand, that its scientific right of existence is doubted. 

 While outsiders who may occasionally have seen a chemical experi- 

 ment, or may have heard of the grand applications of chemistry 

 to practice, declare chemistry to be the finest science of all, 

 although they may not be able to form an idea concerning its 

 scientific aims, other one-sided representatives of so-called 

 humanistic studies, who also mix up the applications of 

 chemist(y with its scientific task, tend towards the unjustifiable 

 view that chemistry ought really to be taught only at polytechnic 

 schools, but not at the "universitas litterarum." 



The propagation of such erroneous conceptions renders it the 

 duty of the chemi.t to appear as the defender of the science be 

 represents, and it will doubtless be considered fully justified if 

 to-day I try to explain to you the scientific position of chemistry 

 and its participation in the great progress of universal science. 



Chemistry has often been designated as the sister of physics, 

 and both subjects are in reality so nearly related, their dornains 

 are so contiguous, that the layman cannot understand the differ- 

 ence, and that even the scientific man can hardly fix the limits. 



Chemistry and physics together form that group which may 

 be designated as general natural science, inasmuch as the occur- 

 rence of their materials of study is unessential, and the laws 

 recognised by them are valid everywhere. Astronomy, geo- 

 graphy, geology, botany, and zoology (the latter including those 

 more special subjects treating of man, and which form the scientific 

 part of medicine), all these, which ought to be comprised under the 



I Address delivered on a'sum'ng the Rectorate of the Rhenish Friedr.'ch- 

 Wjlhelms University of Bjnn, October 18, 1877, by Prof. Aug. KeKule. 



