8o 



NA TURE 



[XoVE.MliER 24, 1S98 



Bridge, he was created a Baronet in 1890. He was president of 

 the Institution of Civil Engineers in 1866, and delivered from 

 the chair a very memorable address on the requirements of a 

 complete engineering education. In 1S90 he received the 

 honorary degree of LL.D. from Edinburgh University. 



Prof. Chari.f.s-Michel Brisse, whose death occurred on 

 October 13, was born in Paris on September 8, 1843, and lived 

 a life of activity and usefulness. He was professor of mathe- 

 matics at the lycee Condorcet for twenty-four years, and he 

 also held the posts of tutor at the F.cole Polytechnique, 

 supplementary professor at the Conservatoire des Arts et Metiers, 

 professor at the ficole Centrale, and professor at the Ecole des 

 Beaux-Arts. He was the author of papers on the displacement 

 of figures and on the general theory of surfaces, and he trans- 

 lated into French several English and German works on the 

 higher branches of mathematics. He also published numerous 

 memoirs on actuarial subjects. In collaboration with M. Andre 

 and M. Riviere, he published two editions of a " Course de 

 Physique " for use in classes of mathematical physics. He was 

 connected with ihe Journal de Physiijue for many years, and an 

 appreciative note upon his services to the journal and to science 

 appears in the November number. 



The temperature-entropy or " thela-phi " diagram of a 

 substance, in thermodynamics, has been made well known to 

 engineers through the writings of Mr. J. Macfarlane Gray. 

 Those who wish to become familiar with an actual theta-phi 

 diagram, or to study the properties of steam by its aid, will be 

 glad to know that a diagram for one pound of steam at tem- 

 peratures from 100° to 400°, designed by Captain Sankey, is 

 now published by Messrs. Albert Frost and Sons, of Warwick 

 House, Rugby. The basis of the chart is the water line and 

 saturated steam line, and the space between these is closely 

 divided by constant pressure and constant volume lines, which 

 are extended into the superheated steam field ; lines of constant 

 drj'ness-fraction are also given. There are scales giving total 

 heat, water-heat, and internal energy, from which these quan- 

 tities can be read oiT without interpolation. 



Mr. Philip E. Bf.rtrand Jourhain sends us several 

 notes reprinted from the Journal of the Royal Microscopical 

 Society, 1898, pp. 395-400, dealing with improvements in micro- 

 scopic lenses, with especial reference to photo micrography. In 

 the first of these notes he describes and figures an apochromatic 

 objective and projection-ocular without fluorite, computed by 

 Prof. Charles S. Hastings ; but no information as to the precise 

 nature of the glasses seems to be divulged by the makers. In 

 a second note Mr. Jourdain describes a method of adjusting the 

 sizes of the coloured images yielded by the Cooke lens ; while a 

 third note is devoted to a description of the planar lens recently 

 computed by Dr. Rudolph, which, on account of its large 

 aperture and wonderfully perfect astigmatic corrections, is 

 admirably adapted for low-power micrography. 



A SHORT article on the colours of lakes and seas, by Prof. 

 Richard Abegg, of Giittingen, has been reprinted from the 

 Natiirwissenscha/tlk/ie Rundschau, xiii. 14. The author 

 upholds the theory of Bunsen to account for the connection 

 between the blutness of water and its purity : namely, that 

 water itself absorbs red and yellow rays in preference to blue, 

 and the purer the water the greater distance has the light to 

 travel before being reflected by suspended particles, and there- 

 fore the greater the preponderance of blue. Hunsen's theory of 

 selective absorption, combined with Soret's application of 

 Tyndall's theory of the colours of the sky to water, arc regarded 

 by Prof. Abegg as affording a satisfactory qualitative solution 

 of the question ; but a number of interesting problems of a 

 quantitative character still remain to be solved, and in this 

 NO. 1517, VOL. 59] 



1 



hi 



connection M. Springs investigations are criticised at some 

 length. 



Some remarkable facts with regard to the electrical trans- 

 mission of power in mining were brought forward by Mr. W. B. 

 Esson in a paper read at the Institution of Civil Engineers on 

 November 15. It was shown that the disadvantages attendant 

 upon expensive transport of ore have been to a large extent 

 neutralised by the electrical transmission of power. By using 

 electrically-transmitted power the crushing-mills can be placed- 

 at the mine, and the serious expense of transporting the ore to 

 the site of the water-power can thus be saved. Generally, 

 electricity furnishes the only practicable means for transmitting 

 power for mining operations, and the ease with which a copper 

 wire can be carried over any kind of country, together with the 

 plastic nature of the material, renders the electrical conductor 

 the simplest and most trustworthy of all vehicles for power 

 transmission. The plant erected at the Sheba Gold Mining' 

 Company's mine for the electrical transmission of power to the^ 

 crushing-mills, five miles distant, was described by Mr. Esson, 

 and the cost of milling was shown to be \s. %d. per ton of ore, 

 as against 6i. \d. per ton when aerial ropeway transport was 

 used, and i/. I2.t. 61/. per ton during the time of ox-waggoi 

 transport. The water-power is obtained by a dam across the| 

 Queen's River, two miles above the generating station, to which 

 the water is conveyed partly in open race and partly in tunnel. 

 The maximum head derived is 32 feet. The turbines are of the 

 Victor horizontal type, driving a countershaft of 300 revolutions 

 per minute by ropes, and are together capable of developing 

 396 horse-power. The generating plant consists of three alter- 

 nating-current dynamos supplying current at 3300 volts. The 

 current is transmitted by cables to the mine, and at the re- 

 ceiving-house the pressure is reduced to 100 volts for driving 

 motors and lighting the workings. The crushing-mill at Sheba 

 works night and day ; and in one year, of the possible 365 

 days of 24 hours each, the pressure cut off the conductors was 

 only 4 days, 8 hours, 22 minutes, which were chiefly occupied 

 in inspecting the water-race, overhauling the belts, ropes, &c., 

 and in executing general repairs to the machinery. The 

 efficiency of the plant from the turbine shafts at the generating 

 station to the motor shafts at the mine may be taken as 70 

 per cent. 



" It is now some eighteen years since Mr. George Eastman, 

 as an amateur photographer, began experimenting in a dark 

 room in his own house with the intention of manufacturing 

 photographic dry plates. . . . This was the modest beginning 

 which blossomed in 18S1 into the Eastman Dry Plate Company." 

 So writes " Hermes " (C(;w»«t'nv, October 26, p. 785) in his 

 interesting article under the heading " Every one his own 

 photographer." Most of our readers have practised the art of 

 photography at some time or other, and many have, without 

 doubt, been users of the well-known Kodak and Eastman's films 

 and papers. It is with these that the writer of the above- 

 mentioned article deals ; in fact, he gives an interesting digest of 

 the history of this big firm since its commencement. So great 

 and rapid has been the growth of this company, that in addition 

 to their large manufactories in Rochester, New \ork, an equally 

 large establishment has grown up in England, having its chief 

 works at London and I larrow. The latter send their photo- 

 graphic materials over the whole world, with the exception of 

 America, which is suiiplied from Rochester. Users of these 

 materials will therefore read this article with interest, for not 

 only will they be made acquainted with the numerous buildings 

 and show-rooms by means of excellent reproductions, but the 

 workshops and other manipulating sections are interestingly 

 described by " Hermes," who has made a lour of all the 

 company's premises. 



