January 9, 19 13] 



NATURE 



525 



fields selected for description. Most of the advances 

 which receive notice have been mentioned in these 

 notes, but there are two which have not, and which 

 deserve attention. Messrs. Reboul and De Bollement 

 have found that copper and silver at 500° C. eject 

 particles in a vacuum in oxygen, air, and carbonic 

 acid, which form deposits on the walls of the con- 

 taining vessel. In hydrogen no deposit occurs. Prof. 

 Wiener has directed attention to the possibility of 

 protecting balloons from lightning by replacing the 

 cord netting now in use by netting containing wire, 

 so that the balloon is virtually in a wire Faraday 

 cage. He has also suggested the insertion in the gas 

 valves of the Davy lamp arrangement of fine copper 

 wire netting so as to protect the gas inside the balloon 

 from the effects of electric sparks outside. 



An interesting contribution to the study of the 

 stereoisomerism of the oximes is contained in a paper 

 by Mr. F. Carlo Palazzo on trichloroacetaldoxime {Atti 

 R. Accad. Lincel. vol. xxi., ii., 530). Hitherto only 

 one oxime, melting at 39-40°, has been obtainable 

 from chloral, but it is now shown that this substance 

 probably consists of a mixture of two stereoisomerides, 

 as with water it gives what is apparently a mixture 

 of the corresponding stereoisomeric oximino-acetic 

 acids, one of which is readily decomposed further by 

 alkalies, giving hydrogen cyanide, whilst the other 

 forms a stable alkali salt. These changes are easily 

 interpreted by writing them as follows : — 



H.C.CCI3 H.C.CO.OH 

 I. il — II -*H.,0 + CO., + H.,0 



OH.N OH.N 



II. 



H.C.CCI, 



X.OH 



H.C.CO.OH 



— - stable salt. 



N.OH 



The view that the trichloroaldoxime, melting at 39°, is 

 rcallv a mixture is confirmed by the fact that it can 

 be obtained with a considerably higher melting point, 

 viz. 56°, when carefully freed from its syrupy con- 

 gener, although it is still doubtful whether this mate- 

 rial represents a definite individual. 



The Engineer for January 3 says that there is no 

 hesitation and temporising about the report which 

 .Sir Francis Fox has presented to the Dean and 

 Chapter of St. Paul's Cathedral. Sir Francis states 

 that the cathedral is overloaded, and is actually 

 moving and cracking ; the eight great piers support- 

 ing the dome have moved, and have sunk from 

 4 to 6 in. It is to be hoped that this report will settle 

 once and for all questions affecting the injury that is 

 to be anticipated from subterranean w-ork in the 

 neighbourhood of the cathedral. The Builder of the 

 same date, commenting on this subject, says that, in 

 view of the report, the abandonment of the London 

 County Council proposal to construct a tram subway 

 in the immediate vicinity of the fabric is practically 

 assured ; in face of such a report it would be folly to 

 proceed. 



An interesting article in Engineering for January 3 

 on the Daimler motor-omnibus gives some account of 

 NO. 2254, VOL. 90] 



the process of elimination whereby the present highly 

 efficient motor-omnibus has been produced. In this 

 process of natural selection, the police authorities 

 gave very great assistance by avoiding the institution 

 of any initial standard of perfection, and gradually 

 increasing their requirements as experience was 

 gained. The forward drives on the present omnibus 

 are either direct or through chains, spur-gearing 

 being used solely for the reverse. This plan is in 

 consequence of the pressure of the London police 

 authorities, who insisted that the omnibus should run 

 as silently on low gear as on high. Helical wheels 

 were tried, but failed to satisfy the demands of the 

 authorities. In desperation almost, chain drives were 

 installed, though the makers of the chains declared 

 that they did not think that they would last a week, 

 since not only w-as the pressure transmitted high, but 

 the chain speed exceeded 2000 ft. per minute. As 

 the event has proved, however, these prognostications 

 were falsified, the chains giving a very satisfactory 

 service. The chain pinions are of high-carbon steel, 

 unhardened ; the spur-gears used for the reverse are 

 of nickel-clirome steel, case-hardened. 



OUR ASTRONOMICAL COLUMN. 



The Attraction of Sun-spots for Prominences. — 

 In an illustrated article appearing in No. 4, vol. xxxvi., 

 of The Astrophysical Journal, Dr. Slocum shows that 

 in some cases sun-spots apparently have a very strong 

 attraction for prominences. He deals especially with 

 a large group of spots which first crossed the solar 

 disc between August 2 and 15, 1910, and received the 

 Greenwich number 6874 ; at the next apparition it was 

 numbered 6880, and, reappearing on September 27, as 

 an extended group, its parts were numbered 6894 and 

 6S93. 



At each apparition active prominences and large 

 flocculic areas were observed in the immediate neigh- 

 bourhood of the spot, the best prominence displays 

 occurring at the west limb on October 8, and at the 

 east limb on October 22. Photographs, in calcium 

 light, taken on the former date, show that the promin- 

 ences were pouring down from both sides right into 

 the large spot. So many jets are visible that there 

 can annarently be no doubt as to their common direc- 

 tion ; moreover, the measures of successive photo- 

 graphs indicate accelerated velocities for the matter 

 forming these jets. Three bright knots, shown on 

 photographs taken at 4h. 26'6m. and 4h. 34'gm., re- 

 spectively, show velocities along the apparent trajec- 

 tories of 16, 20, and 60 km. per second at distances 

 of 170,000, 130,000, and 75,000 km. from the centre 

 of attraction ; other points recognised on two photo- 

 graphs give velocities ranging from 15 to go km. per 

 second. In addition to the general feature of attrac- 

 tion there is also evidence of repulsion, but the jets 

 showing this are very short-lived. 



The distances over which the attractive force of the 

 spot appeared to exert its influence are remarkable. 

 The prominences covered 45° of the solar limb, and 

 prominences 260,000 km. (162,500 miles) from the 

 spot were evidently drawn towards it. 



Both Hale and Evershed have previously found 

 evidence for this spot attraction, but Dr. Slocum's 

 observation differs from theirs inasmuch as he finds 

 accelerated velocities for the prominence matter, 

 whereas their observations indicated diminishing 

 velocities. 



