7 i6 



NA TURE 



[November 25, 1922 



the sum of between 13,000/. and 14,000/. has been 

 expended in research. There is no doubt that this 

 policy has greatly enhanced the reputation of the 

 Institution and has been of the utmost value to the 

 engineering world. The time has arrived when the 

 relation of the fnstitution to the National Physical 

 Laboratory and the Government Department of 

 Scientific and Industrial Research must be carefully 

 considered. In view of present-day demands on the 

 Institution and its members in all parts of the world, 

 the council must consider to what extent, if any, it 

 will be able to contribute in future to researches 

 which may well be left in the hands of the above- 

 mentioned bodies. The Institution is closely 

 associated with both bodies through several members 

 of council, and these will continue, as in the past, 

 to give freely their services and experience. There 

 is also a feeling that the Institution should not 

 encroach upon the ground which newer and special 

 Institutions are better qualified to undertake. 



Prof. Hele-Shaw has long been known for his 

 interest in inventions, and his remarks on inventions 

 and inventors are of value. All progress, at any 

 rate in mechanical science, must be in the nature 

 of invention. Every step taken in which new ground 

 is trodden, every new device or new mechanism, 

 or new- machine of changed form, in which the 

 movements of parts differ, or even if the object 

 attained is different, can result only from the exercise 

 of the inventive faculty. If a man cannot do more 

 than alter the dimensions of the machinery which 

 he is constructing, he cannot be called an engineer 

 at all. Even where it is necessary to duplicate 

 indefinitely any existing machine or machine part, 



invention is required, and has in recent years been 

 exen ised in a wonderful way for production purposes. 



The present stress of competition necessitates the 

 more intense application of the inventive faculty, 

 and an average of 30,000 patents is taken out each 

 year by inventors searching for new devices and new 

 results. It is easy to see what a hopeless task is 

 being attempted by the ignorant and uneducated 

 inventor. In one case he is probably attempting 

 to discover something well known ; in the other 

 lie lacks the education which would prevent him 

 from attempting the hopeless task of trying to 

 produce the impossible. Any one who studies the 

 Patent I '"in mil week by week must see that even 

 to-day the attempts of a large number of inventors 

 would he ludicrous if they were not in most cases 

 pathetic. The truth, however, must be told — 

 engineers in practice in the course of their work 

 constantly spend large sums of money on inventions 

 which, if they are more plausible, are not less im- 

 possible than those above mentioned. 



Prof. Hele-Shaw has long thought that, bevond 

 general engineering training, the time has come for 

 .111 ai tii.il chair of invention. He hopes to see such 

 a chair founded somewhere, and that a professor of 

 invention may give lectures (one or more a year) to 

 engineering students of different schools throughout 

 the country. This would enable the principles on 

 which success depends to be placed before rising 

 engineers, as well as the methods of obtaining 

 information on what had been already achieved in 

 any subject, the cause of failure in previous attempts, 

 and how to approach new problems so as to avoid 

 falling into endless repetitions of previous workers. 



THE complete story of the breeding of the 

 *■ European eel has now been told by Dr. 

 Johs. Schmidt in a memoir published by the Royal 

 Society (Phil. Trans. B, vol. 211, pp. 179-208, plates 

 17, iS, April 4, 11)22). The publication will become 

 a classic of science, not only because of its literary 

 charm and the results that it sets forth, but as a 

 record of the resolution of a man of science determined 

 to carry his investigation to a satisfactory conclusion. 

 In May 1004 Dr Schmidt, while working on fishery 

 research on board the Danish Fishery vessel Thor 

 west of the Faroes, found a Leptocephalus larva 

 of -\ cm. in length. " With little idea, at that time, 

 of the extraordinary difficulties " of the investigation, 

 he began his research. From then till 1910 he made 

 what use he could of the Thor, but the vessel was 

 too small. He obtained collections made by the 

 Michael Sars and others stored in Danish museums, 

 hut the material was very inadequate. Then he 

 persuaded various Danish shipping companies to 

 help, and the skippers were supplied with nets and 

 instructions. One ship-of-war also assisted. In 1013 

 a Copenhagen company allowed him the use of the 

 Margrethc, and for five months all went well. Then 

 tile .1/iy; fictile was wrecked on a West Indian island, 

 but the collections fortunately were saved " ! In 

 1914 and 1915 the United States Fishery vessel Bache 

 and two Danish traders obtained plankton samples, 

 and then the war stopped all further collecting till 



1920. Finally, a Copenhagen company gave Dr. 

 Schmidt the use of the Dana, and with the experience 

 gained, abundant collei turns were made in 1020 and 



1921. It was then, " with mingled feelings," that 

 he found that ^he rich material included two species 

 of eels, the American and European. These could 

 only lie separated by laborious countings of the 

 myotomes and pigment spots, and all this had to 



NO. 2769, VOL. I IOJ 



The Life History of the Eel. 



be done aboard ship immediately after the fishing 

 operation. 



The outcome of all these difficulties is the almost 

 complete story of the European eel. For a period 

 of five to twenty years, according to sex, climate, 

 and quantity of food, the eel remains in fresh water. 

 It is vellow-green in colour and without metallic 

 lustre. Then the desire for food fails ; the migratory 

 instinct awakens ; the silvery " bridal dress " is 

 assumed, and the eels descend to the sea. This is 

 the last that is seen of them, and the period of their 

 migration is unknown. Sometime during the spring 

 or summer, however, they spawn, in deep water, in 

 tin West Atlantic between about 22' and 30' X. lat. 

 and 50 and 65° W. long, (roughly in the middle 

 of the Sargasso Sea). The smallest larva; caught 

 are about 7 to 15 mm. in length, and they are 

 found at about 200 to 300 metres from the surface. 

 From then onwards their area of distribution widens. 

 They rise to near the surface of the sea and begin to 

 10 the north-east. In the first summer they 

 are about 2=, mm. long, and are found west of 50" W. 

 long. In the second summer they are 50 to 55 mm. 

 long, and they then inhabit the central Atlantic. 

 In the third summer they are about 75 mm. long, 

 and 'in now be found on the European coastal 

 banks. They are still leaf-shaped, transparent 

 Leptocephali, but in the autumn they undergo 

 metamorphosis and enter the rivers as the cylindrical, 

 smoky-brown elvers, about three years in age. The 

 further history is well known : they may ascend 

 rivers to a height of 3000 feet above sea-level (in 

 Switzerland). Growth proceeds, and some five to 

 twenty years later the seaward migration occurs. 

 Ill' story is unique in natural history, not only for 

 its own interest, but also because of the patience and 

 resolution with which it has been elucidated. J. J. 



