332 



NATURE 



[June 21, 19 17 



OVR ASTRONOMICAL COLUMN. 



Comet 1916& (Wolf). — The followin^^ continued 

 ephemeris of this comet, which is now very faint, is 

 given by Dr. Kobold : — 



Decl. 



Log r 

 0^273 



Log A . 



OO/.^I 



Mftg. 



0-22S2 



0-2295 



00677 

 00604 



June22 22 32 14 -1-2.3 51-9 



24 36 6 24 3-5 



26 39 53 24 13-5 



28 43 35 24 220 



30 47 II 24 288 



July 2 50 42 24 340 



4 54' 7 +24 37-6 0-2312 00531 lo-i 



The ephejTieris is for Greenwich mrdnight. 



Solar Prominences in Relation to Sun-spots. — 

 It has hitherto been generally supposed that solar pro- 

 minences are inevitably, or usually, found in close 

 connection with sun-spots and flocculi, but an ex- 

 tended investigation which has been made by Dr. 

 O. J. Lee appears to show that there are no substan- 

 tial grounds for this supposition (Astrophysical Journal, 

 vol. xlv., p. 206). His conclusions are based on the 

 photographs taken with the spectroheliograph of the 

 Yerkes Observatory between March, 1904, and January 

 of the present year, thus covering more than a spot 

 cycle. Only 58 per cent, of 4068 prominences of all 

 sizes, which were observed between +4.^;° and —45° of 

 solar latitude, were found in the immediate vicinity of 

 spots, and in the same region only 8 per cent, of the 

 prominences were associated with flocculi in which no 

 spot was observed. On the other hand, 81 per cent, 

 of the seventy-eight filaments observed near the solar 

 limb showed a connection with prominences. A con- 

 siderable number of the large eruptive prominences 

 occurred either in unmarked regions of the solar sur- 

 face, or where the surface was roughened. Intensely 

 bright places in areas of flocculi, when traced to the 

 limb, usually showed as jets, and rarely as promin- 

 ences of any size. 



The Eclipsing Variable SS Camelopardalis. — 

 Some interesting results with regard to this variable 

 ■have been derived by R. J. McDiarmid from a series 

 of nearly 1 1 ,000 observations made at Princeton be- 

 tween. March, 1913, and December, 1915 {Astrophysical 

 Journal, vol. xlv., p. 50). The period is 4d. igh. 47m. 

 6-4S., and the yisual and photographic magnitudes of 

 the system are respectively 10-15 and 9-9. The depth 

 of primary eclipse is 057 mag., and that of the second- 

 ary 0-15 mag. The primary eclipse lasts twenty-one 

 hours, and is total for seven hours, while the second- 

 ary is annular and of the same duration. The discus- 

 sion of the observations indicates that the system con- 

 sists of a large red star of low surface brightness and 

 a smaller white star of a little more than one-third 

 the diameter of the other. The surface brightness of 

 the whiter star is five times that of the larger star 

 visually, and twelve times photographically, -so that 

 the smaller star is visually the faiflter and photo- 

 graphically the brighter of the pair. The density of 

 the large red star is about 1/200, and that of the 

 smaller white star about 1/ 12 that of the sun. The 

 combined spectrum is recorded as F?, and it is con- 

 sidered jiot improbable that the small star is of type 

 A, while the larger is of type G or redder. 



• Hind's Variable Nebula.— The variable nebula 

 N.G.C. 1555 has been photographed by Mr. Pease on 

 seven occasions since December, 1911, with the 60-in. 

 reflector at Mount Wilson [Astrophysical Journal, vol. 

 xlv,, p. 8q). The most prominent feature is a fan- 

 shaped nebulositv, having its apex 25" south-west of 

 the irregular variable star T Tauri. Two knots near 

 the apex, each with a streamer running southward, 



NO. 2486, VOL. 99] 



are the brightest parts of the nebula. The sides of the 

 fan include an angle of 70°, and are about one minute 

 of arc in length. A curved stream of faint nebulous 

 matter lies to the west of the star, and midway between 

 this and the star is a knot which varies in size and 

 brightness. There is also evidence of very faint ex- 

 tended nebulosity filling the whole starless region in 

 the neighbourhood of the variable star. The photo- 

 graphs show distinct changes in the form and inten- 

 sity of the nebula, but the available data are not suffi- 

 cient to establish a relation to the variability of the 

 star. Mr. Adams finds that the spectrum of T Tauri 

 is of type Md, with additional bright lines, and that 

 the parallax is of the order 005" to o-io"; the bright 

 lines extend beyond the dark lines of the spectrum, 

 and would thus appear to be due to the surrounding 

 nebulosity. 



THE NATIONAL PHYSICAL 



LABORATORY. 



npHE annual meeting of the General Board of the 



■*■ National Physical Laboratory was held at the 

 laboratory on June 19. The president of the Royal 

 Society, Sir J. J. Thomson, is chairman of the board, 

 and Lord Rayleigh chairman of the Executive Com- 

 mittee. 



During the past year the laboratory has been closely 

 engaged, with a largely augmented staff, of whom 

 more than one hundred are women, on a variety of 

 researches and , investigations arising out of the war, 

 and has dealt with a greatly increased volume of test 

 work for Government departments. The outstanding 

 feature of the year has been the, growth of the gauge- 

 testing work. Nearly the whole of the gauges re- 

 quired for the inspection of munitions are now 

 examined at the National Physical Laboratory, the 

 number averaging about 10,000 weekly. By arrange- 

 ment with the Ministry of Munitions a new building 

 has recently been erected to accommodate the work, 

 the space otherwise available having become quite m- 

 sufficient for the purpose. There has been a great 

 increase also in the number of optical and electrical 

 instruments tested for the .Admiralty; a new branch 

 of work is the testing of luminous dials for instru- 

 ments of various kinds. 



The investigations carried out have been, in the 

 main, of a confidential character, and no details are 

 given in the report. It has only been possible to 

 make progress with a very few of the researches 

 undertaken prior to the war, and these are almost 

 entirely closely connected with war problems. Aero- 

 nautics research has continued to be of great import- 

 ance. The William Froude National Tank has carried 

 out much work for the Admiralty, and has been visited 

 by members of the Board of Admiralty — including Mr. 

 Balfour when First Lord— who have expressed much 

 appreciation of the results attained. Ln the metallurgfy 

 department researches on light alloys and on optical 

 glass have been continued, while a number of special 

 problems have been dealt with. Various investiga- 

 tions have been in progress in the engineering depart- 

 ment; hardness tests, methods of impact-testing, the 

 fatigue resistance of materials under combined bend- 

 mg and twistinsf stresses, the transmission of heat 

 from surfaces to fluids flowing over them — as in the 

 flow of air over an aeroplane engine — are among the 

 questions examined. The observations on the rate of 

 growth of cracks in the buildings of the Tower of 

 London have been continued. No serious disturbances 

 have been detected. 



The laboratory is at present under the control of a 

 General Board and an Executive Committee appointed 

 bv the Roval Societv and the great technical institu- 



