December 22, 192 1] 



NATURE 



547 



the opportunity to read the original papers, and perhaps 

 more especially by chemists who are intimately con- 

 cerned with the results of such investigations, but 

 may not have been trained to the point of being able 

 to follow in detail the methods by which the results 

 are reached. 



A NEW method of automatic electric welding was 

 described to the Institution of Electrical Engineers 

 on December i by L. J. Steele and H. Martin. 

 Welding by means of an electric arc has long been 

 practised by electrical engineers, but it has draw- 

 backs since the mechanical strength of the weld is 

 sometimes unsatisfactory. As the result of a lengthy 

 experimental research the authors find that when the 

 following sequence of operations is carried out the 

 weld is always successful. In fixing a brass stud to 

 a steel bulkhead, for instance, an arc is first struck 

 automatically between the stud and the bulkhead. 

 The stud is then moved in the direction of the arc 

 until it makes firm contact with the steel. The cur- 



nt is then broken after a brief interval. The whole 

 -operation is done automatically, and perfect welds 

 have been obtained between brass or manganese- 

 bronze studs and steel, iron, or brass plates. The 

 method solves the problem of electrically welding 

 metals of widely differing character and very differ- 

 ent cross sections. It is of particular value in ship 

 construction, since it does not weaken the bulkheads 

 or make them less watertight. It will be of value, 

 also, in bonding rails together for electric traction. 



Part 2 of Messrs. Wheldon and Wesley's Botanical 

 Catalogue (New Series, No. 3), has just been issued. 

 It contains nearly 6000 titles, classified as follows : 

 early botany ; Linnaeus ; botanical journals and trans- 

 actions; botanic gardens; histor}-, classification, 

 nomenclature, biography, etc. ; structural botany and 

 text-books ; phanerogams ; fossil botany ; flora of 

 British islands ; local British floras ; flora of Europe ; 

 flora of Asia ; flora of Africa ; flora of America ; flora 

 of Australasia ; diatomaceae, desmidiaceae, etc. ; 



i marine algae; fungi; lichens; musci et hepaticae; 



I filices. It should certainly be seen by all who are on 



^ the look-out for books and journals dealing with 

 botany. Copies of the catalogue are obtainable upon 

 application to the publishers, 38 Great Queen Street, 



j VV.C.2. 



I 



The latest catalogue of Mr. F. Edwards, 83 High 

 Street, Marylebone, VV.i, is No. 421, dealing with 



i books on anthropology, folk-lore, and archaeology, in- 

 cluding the early historv' of man, native races, 

 manners, customs, and beliefs, mythology, folk-lore 



i tales, magic, and witchcraft. Upwards of iioo works 



j are listed. 



i 



Mr. Fredk. j. Brodie writes to point out that in 

 the article on "Science in Westminster Abbey, "which 



' appeared in Nature of December i, p. 437, Dr. 

 William Spottiswoode, who died in 1883 while presi- 

 dent of the Royal Society, was incorrectly referred to 

 as " Sir " William Spottiswoode. 



Our Astronomical Column. 



The Markings on Jupiter. — The planet Jupiter 

 will rise on December 25 at 1.14 a.m., and will be 

 visible thereafter until sunrise. It will be due south 

 at an altitude of 33° at 6.50 a.m., and is now favour- 

 ably visible for the study of its surface features. 



Mr. W. F. Denning writes : — •' Some interesting 

 observations have recently been obtained by Mr. 

 Frank Sargent, astronomer at the University Ob- 

 servatory, Durham. On December 9 the South Tem- 

 perate Disturbance, which consists of a dark irregular 

 mass of material and has remained visible for twentv 

 years, was well seen, and its following end came to 

 the central meridian at lyh. 46m. G.M.T., so that 

 its equivalent longitude was 143° (System II.). On 

 December 12 the preceding end of the same marking 

 was estimated central at 2ih. 5m. G.M.T., longitude 

 354°- 



"The length of the object was therefore 149°. Its 

 rotation period, when compared with an observation 

 on June 23 last, was gh. 55m. 30s. On December 12 

 the red spot hollow was also observ^ed, and its centre 

 was remarked in transit at i8h. 31m, (longitude 

 260 9°). This value, combined with one derived by Mr. 

 Sargent on May 24 last, shows the intervening rota- 

 tion period to have been 9h. 55m. 37-8s. The latter 

 marking has been visible for more than ninety years, 

 for Schwabe at Dessau observed, and made a drawing 

 of, the same feature so long ago as September 5, 

 1831. 



"_This hollow or basin in the great southern equa- 

 torial belt of Jupiter has undergone manv changes 

 since its first discovery, and it has been one of the 

 most conspicuous features on the planet, as well as 

 one of the most frequentlv obser\'ed, for it borders the 

 northern side of the great red spot which became a 

 striking object on the planet in 1873." 



NO. 2721, VOL. I08I 



The Ultra-Violet Spectrum of a Cygni- — The re- 

 semblance between the spectra of novae about the 

 time of maximum luminositv and the spectrum of 

 a Cygni has been very generally recognised, the spec- 

 trum of Nova Cygni III, taken at the Norman 

 Lockyer Observatory last year, having proved this con- 

 clusively. The star a Cygni is one which is increasing 

 its temperature, and is tetmed a Giant ; in fact, it is of 

 great importance in the domain of stellar evolution 

 because there are few stars in the heavens which it 

 resembles. For many years its spectrum was con- 

 sidered very peculiar, no one being able to state the 

 origins of most of the lines. It was, however, solved 

 at last, and, as Mr. W. H. Wright writes, "it re- 

 quired the genius of Lockyer to recognise the stellar lines 

 as belonging to groups of metallic radiations which 

 are stronger in the spark than in the arc." Up to the 

 present time its spectrum has been closely studied in 

 the region ordinarily recorded on stellar spectrograms, 

 namely, from K to Hj8, but the ultra-violet section 

 has taken second place. Any investigation which re- 

 stricts itself specially to this ultra-violet region is there- 

 fore ver^' important, especially if there exist spectra 

 of novae for comparison taken in this region. Mr. 

 W. H. Wright (Lick Obser\'aton,- Bulletin No. 332) 

 now fills up this gap by making a detailed examina- 

 tion of this region in the spectrum of a Cygni, and 

 publishing a set of wave-lengths extending from 

 H8 (A. 4x02-0) to A 3245. Further, he compares these 

 values with some records of the ultra-violet spectra of 

 some of the brighter novae taken at the Lick Ob- 

 servaton.'. The result of his comparison is to show 

 that the resemblance between novae near maximum 

 and the spectrum of a Cygni "is found to be even 

 more striking in the ultra-violet than in the violet 

 and blue regions." 



