September 17, 19 14] 



NATURE 



61 



both older and younger, put together; and that this 

 continued year after year, though all the while the 

 great herring fishery was mainly supplied by drafts 

 upon that identical and unfailing brood. That there 

 are fluctuations in the abundance of fish, herring and 

 others, is well enough known ; that there are good 

 spjjwning years and bad, or good and bad years for 

 the survival and growth of the young, is also certain. 

 But an increase of birth-rate or a diminution of 

 natural mortality such as would cause the race of ten- 

 year-old herring to outnumber all the rest put together, 

 from four years old to fifteen, is very hard indeed to 

 imagine. 



Here, as it seems to me, is a clear case of a 

 biological problem, based upon statistics, surrounded 

 by mathematical difficulties, where the biologist cannot 

 possibly be sure of his ground until he has enlisted 

 the help of the mathematical statistician. 



D'Arcy W. Thompson. 



The Red Flash. 



The interesting recent letter (Nature, vol. xciii. 

 p. 664) on the green flash leads me to send a brief 

 note on a much rarer correlative phenomenon, also, of 

 course, due to atmospheric dispersion, viz., the red 

 flash. 



Let there be a cloud low down, with a v^ell-defined 

 lower edge, separated from the actual horizon by an 

 interval of clear sky. Then, at the lower edge of the 

 cloud, just as the base of the setting sun reappears, 

 or that of the rising sun disappears, the red flash mav 

 be seen. 



I have observed the green flash, connected with the 

 top of the sun, scores of times; but the red flash, 

 ■connected with its base, only about thrice, as the 

 conditions are obviously much less frequently fulfilled. 



I venture to think that "flash" is a more suitable 

 term than "ray," for the latter may lead people to 

 suppose that a long streamer of light is to be expected. 

 I last saw the red flash at Clapham (Yorkshire) on 

 September ii, 1913, at 6.30 p.m. It was preceded 

 by a green flash at the upper edge of the cloud. 



It may be well to add that, even when all circum- 

 stances seem to be apparently favourable, no flash 

 {either green or red) may be visible. Mv own experi- 

 ence, now a long one, is that failure is decidedly more 

 frequent than success. 



C. T. Whitmell. 



Invermay, Hyde Park, Leeds, September 6. 



OPENINGS FOR BRITISH CHEMICAL 

 MANUFACTURERS. 



\ S a result of the state of war between this I 

 -^ country and . Germany and Austria an un- 

 precedented opportunity has arisen of making- a 

 firm endeavour to establish the manufacture of a 

 very large number of chemicals which have 

 hitherto been produced mostly abroad. 



It is a mistake to think, as many people do, 

 that most of these are patented articles ; on the 

 contrary, the vast majority are very well-known 

 products in considerable demand, and these ought 

 first to receive the attention of the English manu- 

 facturer. 



It is very desirable, however, and no doubt this 

 course is being largely pursued, that existing 

 manufacturers should endeavour to extend their 

 energies to the production of materials of a similar 

 character to those which they already make, and 

 NO. 2342, VOL. 94] 



j not to enter an unknown field of manufacture un- 

 j less they feel very sure of their ground. We 

 have, in this country, the nucleus of a vast 

 chemical industry embracing all, or very nearly 

 all, the ramifications that have been so ex- 

 haustively extended by the large German chemical 

 works, and now is the time for that nucleus to 

 expand in a natural way until all our requirements 

 and those of our colonies, our allies, and the 

 neutral States can be fulfilled. 



This is a point that requires insistence, as there 

 is considerable danger of manufacturers rushing 

 into the production of materials, hitherto bought 

 from abroad, and only incidentally used in their 

 own business, which in many cases have already 

 been made here, or which, on application to the 

 maker of allied substances, could be produced 

 by him w ith a minimum expenditure of money and 

 labour. Thus the soap-boiler who has formerly pur- 

 chased foreign synthetic perfumes, the perfume 

 maker who has bought aniline dyes, the aniline 

 dye manufacturer who has had to depend on Ger- 

 many for his raw materials, all should apply to ex- 

 isting English manufacturers of their requirements 

 before embarking upon the production of materials 

 foreign to their manufacturing experience. The 

 writer has experienced several ^cases of manufac- 

 turers proposing to prepare chemicals which they 

 imagine have been entirely m.ade in Germany, 

 who have been surprised when informed that such 

 are produced in large quantities in this country. 



At the same time, h«t^ever, there is undoubtedly 

 a great opportunity for starting new manufactures 

 in various directions, but the products to be con- 

 sidered first should be of as simple a nature as 

 possible, especially in the case of organic sub- 

 stances, for the successful manufacture of many 

 of the more complicated of these can only, in most 

 cases, be attained after several years' work. 



As regards those articles which are patented or 

 protected by a trade mark the Board of Trade 

 has made rules (Patents, Designs, and Trade 

 Marks (Temporary) Rules, August 21, 1914), 

 under which a German or Austrian patent may be 

 entirely suspended, so that there need be no diffi- 

 culty in obtaining permission to manufacture 

 according to such patents, and, indeed a large 

 number of applications to this end have already 

 been received at the Patent Office. 



Further, it may be stated that, although various 

 organic substances can only be made with the 

 use of ethyl or methyl alcohol, methylated spirits 

 not being suitable, the regulations with regard 

 to these under the Finance Act of 1902 make it 

 possible to use them in manufacture in a con- 

 venient manner, and it is for the would-be user to 

 suggest to the Commissioners of Customs and 

 Excise the means by which it is prop>osed to make 

 the spirits unpotable. This object is obviously 

 easily attained by using either the raw material 

 or the finished product as the "denaturant." 



Of the actual chemicals for which there is a 

 demand now owing to the stoppage of imports 

 from the continent, perhaps potassium salts take 

 the first place, as the Stassfurt deposits have, for 



