April 25, 1918] 



NATURE 



153 



tn<l 171 ft. The foundations are in beds of black shale 

 md sandstone. Temperature recor-ds in the masonry 

 ■f the Derwent Dam, taken by means of thermophonfes 

 letween the years 1909-15, showed a maximum varia- 

 ;ion of 80° within i in. of the face, and not more 

 than 7° at 30 ft. in the interior. The main aqueduct 

 is 28 miles in length, and consists of 4 miles of 

 tunnels, 7 miles of covered conduit, and 17 miles of 

 main-pipe line. 



A HANDY classified catalogue of college text-books 

 nd works of reference on agriculture, botany, 

 ' hemistr}', engineering, geology, mathematics, physics, 

 technology, and zoology has just been issued bv Messrs, 

 H. K. Lewis and Co.,' Ltd., 136 Gower Street, W.C.i, 

 and should be of service to many of our readers. 



OUR ASTRONOMICAL COLUMN. 



The Companion to Sirius.— In a letter to the Ob- 

 scrvatory for April, the Rev. T. E. R. Phillips directs 

 attention to the fact that the companion to Sirius is 

 now readily visible in instruments of moderate aper- 

 ture. This is accounted for by the circumstance that 

 the companion is now in the neighbourhood of greatest 

 tlongation from the bright star. The star was easily 

 observed by Mr. Phillips with an 8-an. refractor, and 

 it was conspicuously bright in a reflector of i8-in. 

 aperture, but in both cases a quiescent atmosphere 

 was an essential condition. The mean of several 

 determinations gave the position angle of the com- 

 panion as 72- 1°, and the separation as 10-89". ^^^• 

 ]nnes, of the Union Observatory, Johannesburg, also 

 -tates that the companion is now an easy object, and 

 lor 1917-18 gives the position angle 73'4°, and distance 

 II-24". The observations suggest that Doberck's 

 jjeriod of 49*49 years is too short by o"22 year, or that 

 the period is 4971 years. 



Physical Observations of Venus. — Among numer- 

 <jus observations detailed in Circular No. 41 of the 

 Union Observatory, Johannesburg, Mr. Innes reports 

 some interesting observations of the planet Venus. 

 Observations were commenced on November 15, 1917, 

 with the object of determining as nearly as possible 

 the actual date of dichotomy, and these resulted in 

 showing that half the visible disc was illuminated 

 on November 23. The date given in the Nautical 

 Almanac for thi's occurrence, based on geometrical 

 reasoning, was November 299 G.M.T., so that the 

 observed time was seven days in advance of the pre- 

 dicted time. It was remarked by all the observers 

 that while the edge of the planet was very bright, 

 there was a darkish lune along the terminator. It 

 ^\•as also noted that the northern cusp was more 

 acutelv pointed than the southern. 



The' circular also includes measures of eighty-seven 

 double stars, photographic observations of comet 

 1917a (Mellish) and of several asteroids, and three 

 additional sheets of the valuable photographic atlas 

 of the southern heavens which is being issued by the 

 Union^ Observatory. 



The Lunar Crater Eimmart.— Attention has pre- 

 viously been directed by Prof. W, H. Pickering to 

 apparent changes in the lunar crater Eimmart, which 

 are of a non-periodic nature and independent of the 

 moon's phase. A careful study of this crater has been 

 carried on at the Florence Observatory during the last 

 three years by Dr. Maggini, who has made use of a 

 telescope of 4-in. aperture, with powers of 175 and 300 

 iL' Astronomic, March, 1918). The crater is situated 

 on the north-western edge of the Mare Crisium, in 

 longitude 295° and latitude 24° N., and has a diameter 

 of about 40 km. It is best observed about two or 

 three days after full moon, when the Mare Crisium 

 NO. 2530, VOL. lOl] 



is near the terminator. On the western rampart there 

 is a very small crater, which usually appears as a 

 brilliant point, but shows a deep cavity under very 

 oblique illumination. FollQwing a general description 

 of the appearances under different illuminations, Dr. 

 Maggini gives an account of the changes noted in Sep- 

 tember, 1915, and October, 1916, when certain portions 

 were of quite unusual brightness. The observations 

 suggest that the changes originate in the craterlet, 

 which is surrounded by a white deposit, extending in 

 rays somewhat similar to those about Tycho. It seems 

 possible that there is an occasional recrudescence of 

 activity in the craterlet, w'ith emission of a white sub- 

 stance, masking for a time the. craterlet itself, and 

 afterwards dispersing over the surface. Continued 

 observations promise to be of considerable interest. 



THE NATIONAL DYE-MAKING INDUSTRY. 

 *T^ O assure a national supply of dyes, independent of 

 ■*• any foreign sources, it is necessary that in respect 

 of each of the three stages of manufacture — (i) raw 

 products, (2) intermediates, (3) finished dyes — 'this 

 country should be self-supporting. An abundant supply 

 of the necessary raw products is available in Great 

 Britain, and, moreover, their manufacture in the state 

 of purity required for the production of dye manu- 

 facture has long been carried out within the country 

 on a very extensive scale. In respect of intermediates, 

 at the -outbreak of war we were very badly placed 

 indeed, for although at one time or another various 

 firms in this country had manufactured a considerable 

 number of the necessary intermediate products, in 

 most instances they had been forced, by continuous 

 underselling on the part of German firms, to abandon 

 their manufacture. This state of affairs led to the 

 result that the British firms which maiiufactured 

 colours were to a very large extent dependent upon 

 imported intermediate products. The correctness of 

 the statement that before a really national supply of 

 dye can be established there must be a suflicient, and 

 secure, supply of intermediates will not be denied by 

 anyone who has to deal with the manufacture of 

 colouring matters, for without them the dye-maker is 

 in the position of Che dyer who has no supply of 

 colours. Moreover, if the dyewares that are to be 

 produced from them are to be of a kind which will 

 enable our textile industry to compete successfully in 

 the open export market, every dye-maker will admit 

 that the intermediates must he of the finest quality. 



On Saturday last, April 20, a considerable party, 

 representing the Press of this country, visited the 

 works of British Dyes, Ltd., at the invitation of the 

 management of the firm. The chairman of the com- 

 pany (Mr. J. Falconer, M.P.)and the managing director 

 (Mr. J. Turner), in their remarks to the assembly 

 emphasised the great importance of intermediate pro- 1 

 duots, and also the fact that to ensure n sufficient 

 national supply of these compounds of the highest 

 quality was one of the first aims of the company. 

 During the inspection of the works the party visited 

 the research, technical control, and large-scale experi- 

 mental laboratories; colour sheds; plant for the pro- 

 duction of intermediates, both the trial and the large 

 plants being included ; and the various subsidiary 

 plants for the production of the requisite heavy 

 chemicals, gas, power, etc. ; and those present were 

 able (to obtain a very fair idea of the progress that has 

 been made by the company. It must have been 

 gratifying to the visitors to see at work the large 

 plants which recently came into operation for the pro- 

 duction of some of these essential intermediate pro- 

 ducts, particularly to those who had a grasp of the 

 great amount of preliminary work that is necessary 



