Sept. II, 1879] 



NATURE 



461 



Prof. A. H. Church commences a course of ten lectures on 

 the Chemistry of Food next Monday, tlie isth inst., at five 

 o'clock, at the National Training School for Cookery, Exhibition 

 Road, South Kensington. Mr. Church has been appointed 

 Professor of Chemistry at the Bedford College (for ladies), York 

 Place, Portman Square. 



The sixth Congress of Russian Naturalists promises to be 

 very interesting, not only as to the scientific communications 

 expected, but also as to its practical results. It is proposed to 

 form a permanent Commission of representatives of all Russian 

 scientific .societies for the exploration of little-known parts of 

 Russia as to their natural history and geology, with the special 

 aim of the applications of science to agriculture and mining 

 industry. Another Commission will be nominated for the diffu- 

 sion of science among the masses of the people by means of a 

 series of systematical lectures. A group of Russian explorers of 

 the North proposes to form at the Congress of Naturalists a 

 special section for all questions connected with the exploration 

 of the North of Russia and Siberi.i. 



The Couriei- de Tlemcen (near Algiers) describes an interesting 

 if somewhat fabulous discovery. It states that some miners 

 occupied in blasting rocks in the vicinity of the picturesque 

 cascades, discovered the entrance to a cave, the floor of which 

 was covered with water. They ventured upon the subterranean 

 river on a raft, and followed it for some 60 metres' distance, when 

 it disappeared in a vast lake. Here the vault of the cave was very 

 high and covered with stalactites. In many parts the miners had 

 to steer their raft between colossal stalactites which reached down 

 to the surface of the water ; eventually they reached the end of 

 the lake, where they noticed a canal extending towards the south, 

 and into which the waters of the lake flowed. The workmen 

 estimate the length of the lake to be 3 kilometres, and the 

 breadth about 2 kilometres. They brought out a quantity of 

 fish, which, they say, surrounded the raft, and which were found 

 to be blind. 



The optical structure of ice forms the subject of a recent 

 paper by Herr Klocke, in the Nates Jahrbuih fiir Mineralogie 

 (•879, p. 272). He confirms M. Bertin's observation, that in 

 formation of ice the optic axis of the crystal is placed at right 

 angles to the surface whence the cooling proceeds ; and this was 

 the case with water at rest in a freezing mixture. Only the ice- 

 flowers which first cover the sides of the vessel have their princi- 

 pal axis parallel to these. M. Berlin affirmed that the first thin 

 ice-layer forming on water which freezes in an open vessel in 

 cold air has a confused crystallisation, and only after thickening 

 takes a determinate orientation. Herr Klocke differs from him 

 here. He shows that the first needles shooting over the surface 

 are formed parallel to the principal axis, and that then ice-plates 

 are added to their sides, whose optic axis is at right angles to the 

 surface of the water. In the enlargement of these lateral plates 

 to the table of ice extending over the whole water surface, this 

 orientation is preserved from the commencement. Tables of ice 

 quickly formed under disturbing influences or in great cold, as 

 also various plates of sea-ice, showed, on the other hand, aggre- 

 gate polarisation. Various other observations are described. 



We hear that the preliminary operations for opening the coal- 

 mines in the Kaiping department of the Chinese province of 

 Chihli, to which we have before referred, are proceeding satis- 

 factorily. From borings made last winter it would appear that 

 six seams of good coal can be reached, and the construction of 

 two shafts has been commenced. Good clay has been found 

 close at liand, from which bricks will be made for lining the 

 lower ports of the shafts, the upper portions being faced with 

 stone already prepared for tlie jiurpose. Machinery and some 

 miners were shortly expected to arrive from Europe, and the 

 work would then be rapidly pressed forward. 



The temperature of the polar extremities of carbons giving 

 the electric light has been recently investigated by M. Rossetti 

 (jfourn. de Phys., August), using the same method and instru- 

 ments as he used in measuring the temperature of the stm. (The 

 face of a thermo-electric pile is placed at suitable distance to 

 receive rays from a radiating surface of determinate size, and the 

 thermal effect is measured by a very sensitive Wiedemann re- 

 flecting galvanometer ; the temperature is deduced by means of 

 a formula previously established.) We give, briefly, the author's 

 conclusions : — (i) The positive carbon pole, at the moment of 

 production of the light, has always a higher temperature than 

 the negative. (2) These temperatures vary according to variation 

 of the current's intensity. (3) They are higher the smaller the 

 radiating surface, provided, of course, it comprises the extremity 

 of the point. (4) For the negative pole the minimum tempera- 

 ture was 1,910° C, the radiating surface being large and, in 

 part, of small brilliancy ; the maximum 2,532° C, the radiating 

 surface being half the preceding. (5) For the positive pole, the 

 minimum temperature was 2,312°, the carbon being very large 

 and the radiating surface very extensive ; the maximum 3,200° 

 when the carbon was thin and the radiating surface nearly a 

 quarter of that corresponding to the minimum temperature. (6) 

 We may consider the temperature of the extreme negative polar 

 point as equal to 2,300* at least; that of the positive polar 

 extremity is not less than 3, 200°. 



On Saturday last a system of telephonic communication 

 highly promising for the convenience of business men and 

 others was successfully inaugurated in London. The tele- 

 phone used is that of Edison (the loud speaking telephone), 

 with the nature of which our readers are acquainted. A central 

 station called the Telephone Exchange, 'in Lombard Street is 

 put in connection at present with ten private oflices furnished 

 with telephones in various parts of the city. The switch- 

 board at the central ofiice might be connected with twenty- 

 four different stations, this being the most that can be attended 

 to by one person. Any number of switch-boards, however, 

 might be added in the same room, and any station on one board 

 connected with any one on another board. An attendant, who 

 may be a boy, sits in front of the board. Supposing No. 2 

 wishes to speak with No. 6, the person at No. 2 calls the atteni 

 tion of the central attendant by means of an electric bell, while a 

 falling shutter on the switch-board shows the number of the 

 appUcant. The attendant responds, and No. 2 then says, 

 "Connect me with No. 6." The shifting of a pin effects 

 this, and Nos. 2 and 6 are left to communicate with 

 each other. When the conversation is closed, No. 2 signals 

 by the bell that he has finished, and the attendant, removing 

 the pin, separates the two stations. And so with any other 

 numbers. Of course only one station can be connected with 

 another at the same time, but the process of coupling and 

 uncoupling is effected very quickly. Edison's instrument, 

 though known as the loud-speaking telephone, is also suited for 

 conversation almost in whispers, and this was tested on Saturday 

 with very satisfactory results. The telephone is said to have 

 been worked in America without difficulty between stations 100 

 miles apart. It is considered that up to about five miles distance 

 there is no loss of power ; and in practice of the above system 

 even five miles would probably be found an exceptional distance. 

 The utility of the system seems fully demonstrated, and we may 

 look for an extensive application of it in our large towns. 



The common form of speaking telephone relies for its action 

 on currents of electricity developed in helices by the varying 

 strength of magnetic induction when an armature moves in the 

 magnetic field. A second genus of telephone is that which 

 Edison has developed out of his motograph, and which depends 

 solely on the varying friction between two surfaces, one of which 

 is an electrolyte, when a varying current is passed between them. 



