570 



NATURE 



[April \ $, 1880 



a steel magnet can be approached at will. The receiver is an 

 ordinary Bell telephone. It is claimed that the voice is trans- 

 mitted with less alteration of timbre than is usual with other 

 telephones, and that there is a remarkable absence of the scraping 

 noises that are almost inseparable from the employment of 

 carbon transmitters. 



If rumour speaks truly, we are to hear shortly of another 

 scientific invention worthy to stand beside the telephone or the 

 phonograph in point of interest. Announcements of a mysterious 

 tehphote or diaphote, the discovery of two rival American 

 inventors, have lately appeared in the paragraph columns of the 

 non-scientific press, the instrument or instruments in question 

 being declared capable of transmitting light as the telephone 

 transmits sound. The rumour to which we allude, however, 

 and of the truth of which we have authoritative information, is 

 based upon the fact that Prof. Graham Bell has deposited in the 

 Smithsonian Institution a sealed package containing the first 

 results obtained with a new and very remarkable in-trument first 

 conceived by him during his sojourn in England in 1S78. 



M. Marcel Deprez has recently described two important 

 instruments to the Physical Society of Paris. The first is a 

 galvanometer adapted for measuring very strong currents of 

 electricity, and consists of a series of soft iron needles placed 

 between the limbs of a steel horseshoe magnet of great directive 

 force. Parallel to the plane of the=e needles and of the poles of 

 the magnet are wound a few coils of stout wire to carry the 

 current. The needle sets itself almost instantly in the position 

 of equilibrium ; hence it is suitable to measure currents which 

 exhibit rapid variations in strength. The second invention of 

 M. Deprez is an apparatus adapted for continuously registering 

 the total amount of energy developed by a current ; an industrial 

 problem of great importance. The current is parsed through an 

 electrodynameter, being, however, bifurcated ; the larger portion 

 traversing the outer coils, the smaller portion traversing a wire 

 of high resistance and then passing through the movable inner 

 coils. The product of these two partial currents is proportional 

 to the energy of the current ; and as the mutual action of the 

 two coils is also proportional to the product of the two partial 

 currents, nothing more is needed than an appropriate registering 

 apparatus to integrate the various portions of the total amount 

 of energy. In this manner the amount of energy expended in 

 the production of an electric light under any particular circum- 

 stances may be determined. 



At a recent lecture before the Society of Arts Dr. Heaton 

 exhibited a large number of applications of Balniain's luminous 

 paint, a substance based upon the famous "phosphorus" of 

 Canton, and upon the phosphorescent powders investigated by 

 Becquerel. Amongst other interesting matters it was shown 

 that a can of hot water placed upon a shilling surface of the 

 paint dims its brilliance, though it recovers on cooling. The 

 application of a lump of ice produces a contrary effect. A tube 

 of "Canton's phosphorus," prepared more than a century ago 

 by Canton himself, was shown still to possess phosphorescent 

 properties. 



With regard especially to the spectra and composition of 

 nsbuloe, M. Fievez, of the Brussels Royal Observatory, has 

 recently, following the example of Huggins, experimented as to 

 whether an alteration in the luminous intensity of a gas, without 

 modification in the temperature or the pressure of this gas, may 

 involve disappearance of one or several lines in the spectrum. 

 The method he adopted was that of projecting, by means of a 

 lens, on the slit of a spectroscope, a real image of the luminous 

 body (part of a Flucker tube), and then altering the intensity of 

 this image, either by reducing the aperture of the projection-lens 

 or by displacing a diaphragm pierced with a circular opening 

 between the lens and the image projected. Hydrogen and 

 nitrogen were the gases. With the former, as the brightness 

 diminished the line II disappeared first, then the line C, the 

 line F remaining last. The lines which disappeared did so by 

 gradually diminishing in length. Nitrogen gave like results, and 

 the following additional experiment was of a confirmatory 

 nature : — If, at a moment when most of the lines are extinguished, 

 the aperture of the slit be increased without changing the p >-i- 

 tion of the screen, the lines that had disappeared return. It 

 seems, then, well established that a gas, though possessing several 

 spectral lines, may be manifested in the spectroscope by presence 

 of a ;ingle line, the others remaining invisible by reason of the 

 little brightness of the luminous body. On this ground certain 

 nebuta showing the lines of nitrogen and hydrogen which longest 



resist extinction are considered by M. Fievez (with Dr. Huggins) 

 to contain those gases, and the relative invisibility of the other 

 lines (relative because they might probably be perceived with 

 more powerful telescopes) is attributed to an absorption in space 

 acting equally on rays of any refrangibility. 



Some experiments byM. Ziloff on the magnetisation of liquids 

 are described in the Journal de Physique for March. It appears, 

 inter alia, that the magnetic coefficient of the aqueous solution 

 of perchloride of iron is not constant, but that it is a function ot 

 the magnetising force. As the latter is increased the magnetic 

 coefficient increases, reaches a maximum for a determinate value 

 of this force, and then diminishes, at first rapidly, and then 

 slowly. 



The action of salts on water-absorption by roots, as studied 

 by Sennebier, Sachs, and Burgerstein, having been left in sume 

 doubt, M. Vesqne has recently made fresh experiments, and 

 on the following plan : — First, the influence of salt and salt 

 mixtures was tried on the absorption of water by the roots 

 if uninjured plants whose aerial parts were subject to un- 

 changed atmospheric conditions. Then their influence on water 

 absorption by a severed branch, then on that of severed roots. 

 M. Yesque's conclusions from the first series of experiments are 

 as follows : — I. Under ordinary conditions, i.e. the plant! 

 suffering no lack of mineral nutriment, distilled water is better 

 absorbed than solutions of salts and nutritive liquids. 2. When 

 plants have been exposed a longer or shorter time to the influence 

 of distilled water they absorb better the solutions of salts and 

 nutritive liquids than pure water. 3. Even a short contact of 

 the roots with distilled water acts favourably on the absorption 

 of salts, and conversely a temporary contact of the roots with a 

 salt solution on that of distilled water. 4. The influences are 

 greater the more concentrated the solutions of the salts and the 

 nutritive liquids. 5. There is no qualitative difference between 

 absorption of the solution of an isolated salt and a nutritive 

 liquid. The experiments with severed roots and branches yielded 

 similar results. These also absorbed more distilled water when 

 they had previously been in salt solution, and took up more 

 ■all' si Union when they had stood for more or less time' in 

 distilled water. 



At a recent lecture at the Conservatoire des Arts et Metiers, 

 on the Industrial Applications of Artificial Refrigeration, M. 

 Raoul Pictet produced a veritable sensation by coining a 

 medallion in frozen quicksilver of the weight of fifteen 

 kilogrammes. 



GEOLOGICAL NOTES 



Devonian Rocks of Belgium. — We have just received the 

 first descriptive memoir issued by the Geological Survey of 

 Belgium. It is a quarto pamphlet of some seventy pages by 

 Prof. Malaise, containing an account of fossiliferous Devonian 

 and Cretaceous localities. The author has been at work collect- 

 ing his materials for more than twenty years, and he now pub- 

 lishes a list of 173 places in Belgium from which Devonian 

 fossils have been obtained. These places are arranged stratigra- 

 phically, and the names of the fossils found at each are given. 

 As a contribution to the local geology of Belgium the pamphlet 

 will doubtless prove of service. It is evidently a piece of labo- 

 rious and painstaking work, of the kind that ought to precede 

 the broad generalised summaries which the Survey will eventu- 

 ally be able to present for the information of the world. There 

 is attached to it an index map, on which each of the fossiliferous 

 localities is marked with a coloured spot, to which is attached a. 

 symbol indicating its geological horizon. Though the map is 

 not, in the ordinary sense, a geological one, it tells its story 

 clearly, and will be a convenient guide to those who purpose to 

 visit the fossiliferous sites among the Belgian Devonian rocks. 

 Prof. Malaise prefixes to his statistics a short introduction, in 

 which he traces the history of Devonian classification in his own 

 country and gives the subdivisions of the Devonian system which 

 his ou'n labours have led him to adopt. He modifies Prof. 

 Go selet's arrangement, taking the Couvin shales and limestone 

 with Calceola out of the Inferior and placing it in the Middle 

 Devonian group, together with the Givet limestone, but leaving 

 the shales with Spit ifer cultrijugattis in the Lower. These shales 

 he regards as containing a fauna transitional between that of the 

 Lower and that of the Middle division of the Devonian system. 

 Prof. Gosselet has observed that if the Couvin limestone is 



