September 8, 1904] 



NA TURE 



475 



Leydcn Museum advocates the complete separation of the 

 study and exhibition series, and insists on the great import- 

 ance (if the absoUite protection of the specimens from fire, 

 dust, and light. 



Prof. Plate described a new microscope suitable for ex- 

 hibition in museums ; Prof. Forel a new method of collecting 

 specimens inhabiting the deep water in lakes ; while Prof. 

 Fujii, of Tokyo, referred to some micro-technical apparatus 

 of his own invention. 



Finally, a demonstration was given on the installations 

 of the " concilium bibliographicum," by Dr. Field. 



V 1 1 . — Zoogeography. 



Mr. Schmidt, of St. Petersburg, explained the distribution 

 of the fishes in the northern Pacific, and mentioned that the 

 northern fauna of Japan should be considered as belonging 

 to the .Arctic region, and that the fishes of southern Japan 

 and the west coast of North America are very distinct from 

 those of the northern parts. 



Prof. Simroth gave his views on the origin of the Alps, 

 based chiefly on the distribution of the Mollusca. Dr. 

 Pellegrin, of Paris, described the fish-fauna found in Lake 

 Tchad and the Chari River, which he declares to be very 

 similar to that of the Nile. 



Prof. Forel gave his experiences on the occurrence of 

 Larus ridibundus on the Lake of Geneva. It appears that 

 thousands of these gulls are present on the shores of the 

 lake during winter, and that they migrate northward in 

 March, to return again in October with their young. A 

 few remain all the year round. The principal lines of migra- 

 tion of birds across Switzerland were then described by 

 Prof. Fatio, of Geneva. 



The congress ended with a couple of days of most pleasant 

 social intercourse. The members were afforded an oppor- 

 tunity of seeing the beauties of the Bernese Oberland during 

 an excursion along the Lake of Thun, and an afternoon 

 spent at Interlaken, where a final meeting was held in the 



Kursaal." Saturday was devoted to a trip to Geneva, 

 where, after a lunch and a visit to the museums, the vener- 

 able Mr. de Saussure entertained the guests at his country 

 seat near the city, and a Venetian fete with fireworks 

 brought the congress to a close. 



ROTATION OF SATURN'S RINGS. 

 ^N 1903 November 6, sh. 25m., I observed a large 

 diffused white spot a little north-east of the extremity 

 of the western ansa. It was placed on the bright rim of 

 the interior ring, just bordering Cassini's division, and 

 appeared to extend faintly over the outer ring. 



November 7 was cloudy, but on November 8 there was 

 a clear sky and pretty good definition, but no certain differ- 

 ences of tint could be remarked in the individual rings. 



On November 9, jh. lom., the planet was very faint, and 

 the two ansje seemed equally bright. At 5h. 50m., how- 

 ever, the western ansa was decidedly the more luminous, and 

 the aspect appeared similar to that on November 6. 



November 10, 11, 12, and 13 were cloudy; November 14 

 was stormy with fine intervals, but definition was very un- 

 steady, and no white spot could be discerned on the rings. 



On November 15 there was a clear, frosty sky. At 

 5h. 50m., under good definition, the ring seemed notablv 

 brighter on western than on eastern ansa. 



On November 16 definition was very bad, and no details 

 could be satisfactorily made out. November 17 was cloudy. 



On November 18, jh. to 5h. 40m., there was a good deal 

 of fog, and the planet's image appeared very faint. The 

 western ansa seemed decidedly brighter than the other, but 

 the luminosity appeared diffused and not caused by a definite 

 spot. 



No satisfactory observations were secured after the latter 

 date. The weather was extremely unsettled, and definition 

 generally very bad, so that though the planet was ex- 

 amined, whenever visible, until December 11, no further 

 inequalities in the luminosity of the rings were noted. 



The bright area seen on November 6 and several other 

 evenings appeared recurrent in same position at intervals 

 of 3 days, whence I infer that the rotation period of the 



NO. 1819, VOL. 70] 



ring is about I4h. 24m. This determination is, however, 

 extremely rough, and only useful as affording evidence of 

 the approximate value. 



After I had arrived at this result, I consulted various 

 authors to find what previous estimates had been made as 

 to the rotation of the rings. 



Laplace theoretically computed that the ring ought to 

 rotate in loh. 33m. 36s. (Chambers's " Descriptive 

 Astronomy," third edition, p. 143). In Laplace's " System 

 du Monde," however, it is stated that Saturn rotates in 

 042S day and the ring in 0437 day, the equivalents being 

 = loh. i6m. 17.2s. and loh. 29m. i6-8s. 



Sir W. Herschel, from a spot or luminous point seen on 

 the interior ring in July, 1789, ascertained that the ring 

 revolved round the ball in loh. 32m. 15-45. {Phil. Trans., 

 1790, vol. Ixxx. p. 479). 



Secchi obtained many measures of Saturn's system in 

 1854-6, and apparently detected an ellipticity in the rings, 

 for the discordances were considerable, and harmonised at 

 intervals of 3 and 9 days. He concluded that a period 

 corresponding to that which a satellite would have if 

 situated on the outer ring, viz. 



I4h. 23m. i8s., 

 would satisfy them {Monthly Notices, vol. xvi. p. 52). 

 The correspondence between Secchi 's period and my own 

 roughly ascertained value, being quite independent, is 

 rather singular. 



Now that Saturn is very favourably visible, it is to be 

 hoped that observers will frequently examine the rings for 

 differences in tint or tone which may afford material for the 

 rotation period to be re-determined. 



W. F. Denning. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



The title of professor has been conferred on Dr. Karl 

 Schreber, of Greifswald, for physics, and on Dr. Robert 

 Pschorr, of Berlin, for chemistry. 



Mr. Alexander Lauder, senior demonstrator in chemistry 

 in the University College of North Wales, Bangor, has been 

 appointed lecturer in agricultural chemistry in the Edin- 

 burgh and East of Scotland College of Agriculture. 



In connection with the technical college which will shortly 

 be proceeded with at Stoke-on-Trent, it is proposed to have 

 a school of pottery, which shall not only train pupils, but 

 also act as a central advisory and analytical department for 

 manufacturers. There will also be a mining department. 

 The estimated cost of the building, some 25,000?., has been 

 practically assured, the North Staffordshire Institute of 

 Mining and Mechanical Engineers contributing 4000/., the 

 Staffordshire County Council 4000/., the training authority 

 6oooi., while close on 10,000/. has been promised as voluntary 

 contributions. 



Dr. Anton Lampe and Dr. Hans Benndorf, of Vienna, 

 and Dr. F. Streintz, of Graz, have been appointed extra- 

 ordinary professors of physics. Herr Reinhold Lutz has 

 been appointed professor of mechanical engineering at the 

 Aachen Technical College, Dr. George Schlesinger professor 

 of the theory of mechanical implements in the Berlin 

 Technical College. Dr. Karl Rohn, now professor of 

 geometrical drawing, in Dresden, has been appointed pro- 

 fessor of mathematics in the University of Leipzig as from 

 April I, 1905. Dr. Ludwig Prandtl, now professor at 

 Hanover, has been appointed to the chair of technical physics 

 and agricultural mechanics at the University of Gbttingen. 



The calendar for the session 1904-5 of the Merchant 

 Venturers' Technical College, Bristol, indicates several 

 improvements which have been made recently at this institu- 

 tion. Among these may be mentioned the new experimental 

 steam engine, with its boiler and measuring appliances, 

 and the experimental light and power station now in use 

 by the students. The courses for engineering students have 

 been re-arranged, and provision has been made for a fourth 

 year's course in civil, mechanical, and electrical engineer- 

 ing. The staff of the engineering departments has been 

 strengthened by the appointment of an additional lecturer. 



