Adriano de PAIVA,
La téléscopie électrique basée sur l'usage du sélénium,
TELEPHONY, TELEGRAPHY, & TELESCOPY (by Adriano DE PAIVA)
TRANSLATION OF AN ARTICLE WHICH APPEARED IN THE INSTITUTO OF COIMBRA,
IN MARCH 1878 BY MR. WILLIAM MACDONALD SMITH
[Original en portugais
The scientific activity of our country, little sensitive as a rule, was, in the latter part of last year, unusually excited at the news of the recent discovery of magneto-electric telephone by Prof. Graham Bell, a native of Edinburgh, lately naturalized american. Our public took an interest in the first experiments made with the new instrument which is rarely seen here. Superintended by some of the most distinguished members of our telegraphic staff, these experiments assumed an almost offirial character: the king even consented that some of them should be made in his presence, deigning himself to take part in the performance, and the newspapers, spreading the report of the result obtained, and explaining the multifold appliances which could be made of the instrument, wakened curiosity in places most indifferent to the progress of science. At the same time, thanks to the extreme simplicity of the instrument, it began to be constructed by our artists ; its sale was advertised at very moderate prices and more than one patent for ifs perfection was taken out. (1)
The remarkable enthusiasm created among us by the american professor's discovery cannot however be called excessive, if we compare it with that which it produced in most scientific countries where men of science considered it the last word of electrical telegraphy. Thus it was that in Sir W. Thomson at the Congress of the Royal British Association at Glasgow, in Sept. 1876, when giving an account of the telephone he had seen in the Philadelphia Exhibition and under recent impression, said: "This marvel, gentlemen, is certainly the greatest of telegraphy ; I heard entire sentences which my collegue Watson spoke at the other end of the Philadelphia palace. His voice was carried to me clearly and distinctly, so that I could imagine him distant only a few steps". It was in the same way that in France, Mr Breguet, in an excellent article entitled "Telephonic Telegraphs" did not hesitate to declare openly : - "The discovery of telephony has now filled up the only gap which still existed in the rapid correspondence of the telegraph" (Revue des Deux Mondes, Tome XXV, p.240).
In many articles we have read upon the same subject we have always found the same manner of considering it. The Telephone has been compared exclusively to the Telegraph. It is a Telegraph without any battery, and which realizes a great progress, for instead of transmitting written words, it transmits them under the oral form. It is on this account frequently designated "The speaking Telegraph", an improper term, if we attend to the etymology of it.
Without disputing the existence of incontestable analogies between Bell's telephone and the electric telegraph, it was always our individual opinion, since we began the study of this quesion, that between that chapter of physical science which may be called Telephony, and Telegraphy, there exist essential differences, as also between these two branches of the science and the chapter of Optics which treats of telescopes. And as this way of looking at it led us to direct our attention to a study, which, till a little while since, we had supposed entirely new, permit us to develope our ideas on the subject.
When we meditate a little on the way in which communication between man and surrounding nature is established, two of the organs of our senses appear to reveal a superior importance. These are - the eye and the ear; - the two organs whose functions originated two of the most momentous branches of physics, Optics and Acoustics. And these being the organs specially destined for distant observation, it is not surprising that ever since he began to use them, man should have endeavoured to increase their sphrere artificially. Thus was invented in its most rudimentary form, the first Telescopy, and also the first Telephony, or rather a special branch of it, wich we might call Teleacoustics.
For the relations between men nature destines especially organs which permit of vocal articulations. Words are thus originated, and these obtained subsequently a most useful form, when made permanent by writing. The voice, however, only being intelligible to a limited distance, and the transmission of writing requiring a post, always tardy in the accomplishment of its object, it became necessary to give the voice a more extended reach, and to be able, in the absence of it, to carry on a conversation at a distance by means of conventional signs. Hence another branch of Telephony, which we may call Telelogy, and hence also the first Telegraphy.
It appears to us, therefore, that Telephony comprehends two essenrially different branches ; in one the auditory power is to be increased, in the other the vocal power. The first man who listened attentively, placing his hand behind his ear, realized a rudimentary telephone of the first kind, and the second kind was realized by the man who, to speak at a distance, first hollowed his hands in front of his mouth, or used a porte-voix.
If, however, from the primitive phase we pass to ulterior inventions we find apparatus which can unite in themselves the functions of both species of telephone. Such is the acoustic tube, which even now is employed advantageously up to a distance of 150 metres, and such is the modern Bell's telephone, which, if on one hand may be said to transmit the vocal vibrations of one of the interlocutors to very near the ear of the other, may, on the other hand, be considered as realizing the transport of the concha of the ear to the spot where the sound is produced. We can conceive the possibility of giving this artificial concha such a degree of sensitiveness, that from the centre of a populous city one might listen to the songs of the birds in a forest many miles off ; marvellous result, but which we must consider attainable ever since, with the intent of accomplishing it, the use of electric currents was thought of. What we ought to greet principally in Bell's Telephone, as in the experiments which proceded it, is not the discovery of new telegraphs, the so called speaking telegraphs, but an application, never before made, of electricity, the creation of electric Telephony.
Ever since the preceding considerations were clearly depicted on our mind, we could not help thinking that soon another scientific invention would appear ; the application of electricity to Telescopy, or the creation of electrical Telescopy.
Its realization seemed to us in no wise impossible. In the same way as in the electric telephone, the concha of the ear is, so to say, transported to the point where the sound is produced, and there, uniting the vibrations in a diaphragm, these are transformed into electric currents, which recompose the sound in the receiving apparatus - all which, if internal resistances dit not exist, proportional to the lenght of wire, would be effected without apparent loss of live force - such we imagined ought to be the mechanism of the telescope which we predicted. A camera obscura, placed on the site of the observations, would represent in a way the ocular camera. Upon a plate at the bottom of this camera the images of exterior objects would be depicted, with their respective colors and particular accidents of illumination, affecting thus diversity the different portions of the plate. All that is wanting therefore, here, is the discovery of the method of operating the transformation, by no means impossible, of this energy absorbed by the plate, into electric currents, which should subsequently reproduce the images.
The importance of the discovery of an instrument of this order is manifest. However, it is not perhaps useless to say, that this electric telescope, when realized, would fill up a gap which actual telescopy, notwithtanding all its progresses, never could think of doing. The impotence of catadioptric telescopy is seen when one reflects that astronomical observation being possible at almost infinite distances, the law of rectilinear propagation of light, both direct and reflected, or refracted in homogeneous mediums, prevents our being able to observe any object on the surface of the earth, although the distances are incomparably less, whenever it is below the apparent horizon of the observer. With the new telescope, however, this obstacle would diasappear ; transformed into electric currents, the luminous movement would pursue its way with docility for a distance as extensive as the wire we choose to apply, and from any point of the globe it would be possible to survey any other spot.
We must confess that we thought it strange, in the face of the manifest importance of these reflections, and from circumstance of their being a very natural consequence of the discovery of electric telephone, that nothing at all like them had appeared in any of the many articles we had read upon the subject. For this reason we were led to thinking of the practical mode of resolving the question wich occupied us, and we even imagined several experiments. We communicated our ideas to some friends and colleagues, and they having incited us to publish these thoughts, for the purpose of calling the attention of practical scientists to the resolution of so momentous a problem, we began to write an article on the subject, when a very recent publicationn came into our hands, and there we had the satisfaction of meeting for the first time with something about the instrument, which for the reasons mentioned we called Electric Telescope, and which is there designated the Telectroscope. We saw then that of which the other articles we had consulted, did not speak, though of distinguished physicits, had not escaped Professor Bell, to whom humanity will always be grateful for this marvel.
"The Telectroscope, we read in the book referred to, is an apparatus based, as the telephone, upon electrical transmission. It is composed of two cameras placed, one at the point of departure, and another at the point of two cameras placed, one at the point of departure, and another at the point of arrival. These cameras are united by metallic wires conveniently combined. The anterior inner face of the camera of departure bristles with imperceptible wires, whose apparent extremities form a plane surface -. If any object be placed before this surface, and if the luminous vibrations corresponding to the pecularities of form and colour of this object after being received by each of the conducting wires, are transformed into an electric current, they will be reproduced identically at the ends of these wires. The Boston newspapers affirm that the experiments made in that city were crowned with success, but it is necessary to receive exact descriptions of the apparatus, before crediting this notice." (Figuier, An. sc.)
On our part, we should add nothing on the subject, had we not seen the words of the paragraph we have just transcribed, but on seeing them we may say that the experiments we intended to make, and which we shall still attempt to realize, consisted in the employment of selenium as the sensitive plate of the camera of the telectroscope. This body possesses the remarkable property, recently discovered, of - when interposed in an electric circuit which passes through a galvanometer, - making the needle of the latter deviate sensibly whenever a luminous ray incides on the selenium, and this deviation varies with the color of the light. The following figures indicate the deviations of the galvanometer for different colors.
These results were obtained by Dr. Werner Siemens of Berlin who, having prepared small circular plates of selenium, cooled after having been subjected to a temperature of 210°, which gave them an extreme sensitiveness, succeeeded in constructing a photometer, of very great sensitiveness, as also a curious instrument, a kind of artificial eye, of which his brother, William Siemens, gave a curious description in London, at one of the Soirées of the Royal Society.
We very much wish that selenium applied to the end which we have indicated, should produce the desired effect, if not in our hands, in those of more able professors. It would be a day of the greatest happiness for us to see the electric telephone perfected, and the telectroscope in operation. Respecting the telephone, we think with mons. Breguet, that it will not give all that is expected of it, till a battery is adapted to it, till the voltaic telephone substitutes the present magneto-electric one. In the latter the force which produces every thing is only the force the experimenter calls into action by his own vocal impetus ; we may compare it to a vehicle, in which the motor were simply the strength of the person transported. Not so in a voltaic telephone, in which the battery would be a real reservatory of force, which could be easily disposed of, in the sameway as it is easy to give the desired velocity to a locomotive, because there is always an enormous excess of force in reserve. These reasons appear to us to indicate the fitness of voltaic currents for future telectroscopy.
With these two marvellous instruments, fixed on one spot of the globe, man will be able to extend to the whole of it, his visual and auditory faculties. Ubiquity, from having been utopian, will become perfect reality.
Then, conducting wires charged with all important missions will cross and recross at the surface of the earth ; they will be the mysterious duets which will bring to the observer the impressions received by artificial organs, which human genious has made to compass any distance. And, just as the complexity of nervous filaments can give an idea of the superior perfection of an animal, those metallic filaments, nerves of another order, will testify to the high degree of civilization of the monster organism, - humanity.
O PORTO FEB. 20th 1878.
Signed - Dr. ADRIANO DE PAIVA
Professor of Physics at the Polytechnic of Oporto.
[Ici se termine la brochure de Adriano DE PAIVA, La télescopie électrique basée sur l'emploi du sélénium, Porto, 1880.]
(1) The first notice which appeared in Portugal on the telephone was as we suppose, that in the Secu1o of Coimbra N° 2, 2.d Series Dec.1876, but we wi1l observe that that notice refers to the instrument as it appeared in the Philadelphia exhibition, which is very different to the present one used. It was to the same that Sir W. Thomson referred to the G1asgow Congress in Sept., of the same year (Revue Scientifique of 20th Jan. 1877). The new magneto-electric telephone of Bell was only sent to England in the month of July 1877 and then tried in public meetings. After this it was sent to Paris to the physical constructor, Mr. Breguet, and presented by him to the Academie des Sciences in October 1877. (Comptes rendus hebdomadaires, 1877); the description of it had however already appeared in the Revue industrielle of Messrs. Fontaine and Buquet (8th year n°43, Oct. 24th 1877)., which also contains, in n° 17 and 48, articles upon the subject. At the session of the Paris Académie des Sciences on 26th Nov. 1877, fresh observations were made about the telephone (Comptes rendus, tome LXXXV, n°22). In Portugal the first experiments took place in Nov. 7, 1877, with German apparatus, and afterwards with other made by M. Hermann, of the Telegraphic staff. The experiments which the king attented took place on 21 Dec. 1877 between the observatories of D. Luiz and that of Ajuda ; and on the 25th of the same month the Progresso of Lisboa published an interesting notice on the subject, transcribed we believe from that given by Mr W.H. Preece, C.E. at Plymouth, in a conference of the Royal British Association (Revue Scientifique, 10 Nov. 1877).