358 



NATURE 



\Aug. 24, i87«j 



conferred, has presented the Association with a gift of 

 10,000 francs. The Association has been able to distri- 

 bute assistance to those engaged in scientific research to 

 the extent of 7,000 francs during the past year ; of this 

 sum S,ooo francs was accorded to Dr. Janssen as a con- 

 tribution to the expenses of his recent voyages, and 2,000 

 francs to M. Chapelas-Coulvier-Gravier, to enable him to 

 continue his researches on shooting stars. M. Cornu 

 referred to the great importance of the Puy-de-D6me 

 Observatory, of which we have frequently spoken, and 

 the formal opening of which had been deferred in antici- 

 pation of the present meeting. He concluded by eloquently 

 urging the Association to continue to be animated by the 

 spirit in which it was begun in the days of France's sore 

 distress, to keep free from all party spirit, and to seek to 

 be spoken of only and always as the friend of science and 

 of the country. 



The treasurer, M. Masson, gave an account of the 

 state of the funds, which is very satisfactory. The Asso- 

 ciation is prosperous, numbering 2,200 members, including 

 200 ladies. The receipts for the Nantes meeting were 

 greater by 400/. than the expenses. The funds of the 

 Association amount this year to 7,000/. 



In the evening a reception was held at the Hotel de Villa 

 by the mayor, which was perfectly successful. 



On Saturday, at two o'clock, the several sections met 

 to appoint their officers. Among the strangers present 

 were Lord Houghton, Dr. Gladstone, the Rev. S. J. Perry, 

 Mr. Eaton, Prof. Boyd Dawkins, and several other 

 Englishmen. 



M. de Mortillet, the sub-director of St. Germains 

 Museum, has been nominated the president of the section 

 of Anthropology. He delivered an address on the origin 

 of superstitions. He showed that the present superstitions 

 must be mostly connected with old Celtic populations. — M. 

 Tchebycheff, the Russian geometer, has been appointed 

 president of the Section of Mathematics. M. Tchebycheff 

 exhibited a machine for performing addition and sub- 

 traction with extraordinary rapidity. — M. de Lucas pre- 

 sented the designs for the construction of a machine 

 intended for the fabrication of prime numbers. 



The places of interest in and around Clermont are 

 open to the inspection of the members of the Congress, 

 as is the case at meetings of the British Association, 

 consequently the Sunday excursions have been numerous 

 and highly attractive. The prehistoric archaeologists 

 visited the palaeolithic habitations recently discovered at 

 Issoire. A pleasure trip was made to Vichy, and a large 

 number of members went to Thiers. The excursionists 

 to Vichy were welcomed by the Mayor, Dr. Cornil. Among 

 the toasts proposed was that of Lord Houghton, as a Vice- 

 President of the British Association, who made a suitable 

 reply. 



In the city of Clermont are located the celebrated in- 

 crusting fountains, which convert into stone, wood and 

 even animals. A rich collection of specimens has been 

 opened for inspection, and will be visited officially by the 

 Section of Geology this week. 



An incident has occurred which created a little 

 sensation. The members were assembled in a general 

 meeting to hear a lecture on the mountains of Auvergne, 

 when an intimation was received that the lecturer had 

 been taken ill. M. Claude Bernard, the well-known physio- 

 logist who was present, was therefore invited to deliver 

 an address. He lectured on the sensibility of plants, a 

 subject which he has been investigating. 



SCIENCE IN GERMANY 



{Froin a German Correspondent) 



TV/T "W. SIEMENS has recently endeavoured to determine 



* the velocity of propagation of electricity in suspended 



wires. His method of observation consists in the employment 



of two insulated Leyden jars (or two charge tables), the outer 

 coats of which are metallically connected together. The inner 

 coating of one jar is directly connected by a short wire with a 

 metallic point ; that of the other is also connected with this 

 point, but by a long circuit line. Opposite the point stands a 

 rotating metallic cylinder connected with earth. When the outer 

 coats of the jars are connected with earth, the electricity of the 

 inner coating of both jars at that moment becomes free, and is 

 discharged through the point and the rotating cylinder to earth. 

 If the rotation is sufficiently rapid, and the line long enough, 

 there are produced on the smoked cylinder two marks with an 

 interval between them, which is the measure of the time the 

 electricity took to pass through the wire line from the jar to the 

 point. This arrangement was also modified by placing two 

 points, instead of one, opposite the metallic cylinder ; the one 

 being connected directly with one jar, the other by the line with 

 the other jar. A discharge of the jars was first obtained while 

 the cylinder was at rest, and then the discharge was made with 

 the rotating cylinder. 



M. Siemens thought at first that the velocity of propagation of 

 electricity must be proportional to the specific conductivity of the 

 material. In discharge of a jar through a caoutchouc tube filled 

 with water, or through a wet thread, no time difference could be 

 perceived between the mark of the direct discharge, and that of 

 the first partial discharge through the liquid. It was the same 

 with discharge of the jar through a strong caoutchouc tube, 100 

 feet long, and 20 mm. clear diameter, which was filled with zinc 

 vitriol solution. Now, since a difference of five millionths of a 

 second might be distinctly perceived, it is thus proved that the 

 velocity of electricity in liquids must be over 800 geographical 

 miles per second. As the conductivity of copper is at least 200 

 million times greater than that of the zinc vitriol solution, the 

 velocity of electricity in copper must be at least 160,000 geogra- 

 phical miles if the specific conductivity were synonymous with 

 the velocity of electricity. 



From experiments with longer telegraph lines it appeared 

 that the propagation of electricity in conductors occurs with 

 a determinate velocity independent of the length of the con- 

 ductor ; this is, in iron wires, between 30,000 and 35,000 

 geographical miles per second, (The length of the line 

 was in one case 25*36 kilometres, in others 23 37 and 7*35 

 kilometres.) 



M. Siemens proposes to make similar experiments with a 

 copper circuit in order to decide, by direct experiment, the ques- 

 tion whether the velocity of electricity depends on the nature of 

 the metallic conductor or not. From the experiments made with 

 the caoutchouc tube filled with zinc vitriol solution, he considers 

 the latter the more probable. We may further remark that Prof. 

 Kirchhoff (in establishing Weber's fundamental law for the 

 motion of electricity) already previously obtained the number, 

 21,000 miles, for the velocity of electricity in conductors, and at 

 the same time came to the result, that this velocity must be 

 equally great in all conductors. Siemens's measurements come 

 much nearer to Kirchhoff's values than to that obtained by 

 Wheatstone, viz., 61,900 geographical miles. S. W. 



GERMAN EXPEDITION TO SIBERIA 



A S a sketch of the present state of Central and Northern 

 ■^~*- Asia, it may perhaps not be uninteresting to our readers 

 to have laid before them the following extract from a letter 

 written by Dr. Finsch, who, together with Dr. Erehm and 

 Count Waldburg-Zeil, is at present engaged in the scientific ex- 

 ploration of Southern Siberia, under the auspices of the German 

 Arctic Society. The letter dates from Lepsa, near the Bal- 

 kash-lake. May 13. 



" We started for Lepsa on May 3, and camped the first night 

 in ' yurts ' — tents — ready for us at the foot of the Arkat Moun- 

 tains. The yurt destined for our own use was splendidly deco- 

 rated [for, thanks to the orders of the Czar, the travellers found 

 at each station everything requisite for their comfort and the 

 prosecution of their journey ready for them ; in addition they 

 were always accompanied by a picket of Cossacks, who had to 

 provide horses for them, and to see them safely from station 

 to station.] 



•* Many Kirghiz chiefs, dressed in their picturesque attire, 

 were awaiting our arrival, and we found a repast of pillaf, lamb, 

 and kumis, ready for us. The Arkat Mountains are a mass of 



