Jnne 2, 18S1] 



NATURE 



109 



The works will begin immediately for the construction of the 

 International Exhibition Electrical Railway, as we are glad to 

 state that the request of Messrs. Siemens has been granted by 

 the Municipal Council of Paris. 



Our Paris Correspondent was present last Friday during an 

 experiment made by M. Trouve on a small boat between 

 Port Royal and Pont des Arts. The boat, measuring 5m. 

 50 by I '30, and carrying three persons, obtained a mean 

 velocity of im. 30 per second, with a magneto electric motor 

 weighing 2 kilogr., and two series of six Wollaston elements 

 weighing 12 kilogr. each. The trial lasted an hour and a 

 half, and was interrupted by darkness. These experiments 

 will be repeated shortly on the Bois de Boulogne lakes. The 

 motor, whichw as constriltted to give 8 kilogrammetres per second, 

 did a duty which a .'■ingle rower would have been unable to per- 

 form. The electro-magnetic motor was placed on the rudder, 

 and the motion communicated to a small screw placed in the 

 lower part by a chain. This system is not calculated to utilise 

 the whole extent of the motive power generated by the elements, 

 but it dispenses entirely with any alteration to the boat. This 

 last circumstance is considered as decidedly important in popu- 

 larising the system amongst yachtsmen . There is not the slightest 

 vibration or noise of any description felt on board. 



The lectures which were dehvered in connection with the 

 Glasgow Naval and Marine Engineering Exhibition are about to 

 be published. 



Mr. W. R. Browne has issued a carefully revised edition of 

 the Library Catalogue of the Institute of Mechanical Engineers, 

 combining both a list of authors and of subjects. It also contains 

 a Subject-Index of papers in the Proceedings, 1847-80. 



Mr. C. W. Harding, of King's Lynn, received prizes for 

 two papers at the Recent Norwich Fisheries Exhibition : — i. 

 "Essay on the Artificial Propagation of Anadromous Fish other 

 than the Salmon, and the Re-stocking of the Tidal Waters of 

 our Large Rivers Artificially with Smelts, " &c. ; 2. "On the 

 Utilisation of Localities in Norfolk and Suffolk suitable for the 

 Cultivation of Mussels and other Shell Fish." 



On Monday night shocks of earthquake were felt at the 

 Observatory on Mount Vesuvius and at the villages at the foot 

 of the mountain, especially at Torre del Greco. At nine o'clock 

 on Tuesday morning the seismographic activity was decreasing. 



The Swiss Federal Commis-ion for Meteorology has been 

 definitively constituted for three years as follows : — M. Schenk, 

 president ; Professors R. Wolf (Ziirich), Hagenbach (Basel), 

 Plantamour (Geneva), Ch. Dufour (Morges), Forster (Berne), 

 and Weber (Ziirich), and M. Coaz Inspector of Forests at Berne. 

 The Commission met at Berne on May 23, and discussed the 

 institution of a Central Board at Ziirich. Want of means has 

 prevented it from opening the important meteorological station 

 on the summit of Mount Sentis. 



M. DE Lesseps has been urging upon the Khedive of Egypt 

 the re-establishment of the Cairo Observatory, originally founded 

 by Mehemet Ali ; its fine instruments have been long ago dis- 

 persed among various establishments. The atmosphere of Egypt 

 is peculiarly favourable for observatory work, and we hope the 

 Khedive will take M. de Lesseps' advice. 



A Marine Exhibition ^^ill be held at Hamburg in September 

 next, of -nhich nautical and astronomical instruments will form 

 the principal part. 



A CORRESPONDENT (A. H. McC.) of the New York Weekly 

 Evening Post, writes on the question of the Sound of the Aurora : 

 — In your edition of Saturday I noticed an abstract frpm " Record 

 of a Girlhood," in regard to hearing the aurora borealis, and 

 therefore beg. to give you my experience on the subject. In 



the winter of 1846 I crossed the Atlantic from Newfoundland 

 to Greenock in the brig Amanda. We had strong southecly 

 winds the whole passage, without seeing the sun until after 

 making land ; three days previously a strong southerly gale 

 carried away our only top-sail, leaving us wnihout sufficient after 

 sail, and consequently we were driven far to the northward. 

 The day before we made land the wind suddenly changed to tlie 

 north-west, and as night approached the sky became clear. At 

 about 9 o'clock p.m. the captain called alt passengers ott deck, 

 and a more magnificent spectacle was never contemplated — the 

 whole heaven was a blaze of white light, the aurora darted and 

 rushed from every point and rt fleeted each colour of the rainbow. 

 While it lasted we could distinctly hear the sound, a.s if the folds 

 of heavy silk were shaken, sometimes sharp and quick, and then 

 receding until the sound was lost, according to the intensity of 

 the flash. During most of the time a book could ea-sily be read 

 on deck. The phenomenon lasted about four hours, during 

 which time we all remained on deck. Next morning we made 

 land, which proved to be Barra Head, Southern Hebrides, and 

 were able to lay our course. 



On May 2 the German Fisheries Society held its annual 

 meeting at Berlin, his Imperial Highness the Crown Prince 

 being present. Herr Friedel, the director of the Markische 

 Museum, dehvered a festive address on ' ' Pre-scientific Fishing." 

 Afterwards the president of the Society, ilerr voa Behr- 

 Schmoldow, read the report for the year, which was highly 

 favourable. Some 6,000,000 ova have been "sown out" in 

 German ^\ aters. Excellent results were obtained with 300,000 

 American salmon ova and a similar number of shad ova. The 

 intercourse with the fisheries societies in Austri.i, France, and 

 the United States was very successful and remunerative. 



At the annual general meeting of the Sanitary Institute of 

 Great Britain on May 25, Dr. Richardson, F. U.S., who for four 

 years past has acted as Chairman of Council, and who now goes 

 out of office by rotation, after expressing his thanks to his 

 colleag\ies for all the courtesies they had shown him, said he 

 could not, he thought, conclude his work as chairman more use- 

 fully than by giving a short account of some recently conducted 

 researches which he had made as to the periods of incubation of 

 the infectious diseases which the sanitarian has to combat. He 

 proceeded to indicate that there are twenty-six well-known 

 diseases of this kind, and they each have their special periods of 

 incubation, which, though open to exceptions, are fairly regular. 

 The period of incubation was that period which intervened 

 between the acceptation of the poison that caused the disease and 

 the first manifestation of effect. Disea-es might thus be grouped 

 according to their stages of incubation into five classes — Shortest, 

 Short, Medium, Long, Longest. The shortest period was one to 

 four days : under this head came plague, cholera, malignant 

 pustule, and dissection poison. The second period was from 

 two to six days, and under this head came scarlet fever, diphthe- 

 ria, croup, erysipelas, hooping-cough, influenza, glanders, and 

 pyasmia The medium period was from four to eight days, and 

 in it are included cow-pox and relapsing fever. The long period 

 had ten to fifteen days, and included in it measles, mumps, 

 typhus, and typhoid. The longest period, forty days, included 

 syphilis, and might include hydrophobia. Dr. Richardson con- 

 cluded his address by showuig the important practical sanitary 

 lessons that were connected with a correct knowledge of these 

 periods of incubation. 



The Technological, Industrial, and Sanitary Museum of New 

 South Wales is, we learn, intended to occu| y a simikr position 

 and fulfil the same purpose in that colony which the South 

 Kensington Museum, the Bethnal Green Museum, the Museum 

 of Practical Geology, the Patent Office Museum, and the Parkes 

 Museiuu of Hygiene do in London. To this end, it is intended 



