136 



KNOWLEDGE. 



[June, 1903. 



by certain comets, the immense extent and curvature of some 

 of their tails, and other facts appear to be decidedly opposed to 

 Mr. Shaw's conclusions. Undoubtedly there are shoals of 

 meteoric bodies circulating in planetary space, and it is probable 

 that they are crowded in circumsolar regions, but it is very 

 hard to believe that they could be rendered so strikingly visible 

 over vast regions by the simple effects of refraction exercised 

 by the heads of comets. It seems much more plausible to believe 

 that the tail is horn in a comet, and due to the emission of 

 luminous material from the nucleus under solar action. On 

 page 6 the author says, " the tail of a comet is invariably 

 pointed — if one may use that expression^n the opposite 

 direction to the sun," but this is not always accordant with 

 observation. In certain cases comets have displayed two tails 

 (those of 1823 and 1851 furnished examples), one of which was 

 directed toirarda the sun. Mr. Shaw also alludes to the ttegen- 

 Bchein in his book, .and attributes this appearance to the action 

 of our atmosphere in " focussing the refracted rays of sunlight 

 passing through it." It seems more probable, however, that 

 the phenomenon is due to the reflected light of an assemblage 

 of meteorites in the region opposite to the sun. We have noticed 

 several errors in the book, thus, on page 1 y we read, " the comet 

 of 1774 is recorded to have had six tails." AVe suppose the 

 comet of 1744 is referred to here. On page 27, Donati's comet 

 is stated to have been " discovered by H. P. Tuttle on June 2, 

 1858." ! 



" The Bdrlixgton Mao.\zine." Edited by Eobert Dell. 

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 we offer our new contemporary a right royal welcome. 



A selection of Sir. Lydekker's zoological and other articles 

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THE MOVEMENTS OF THE MACKEREL. 



Bv L. N. Badenoch. 



It is remarkable how little is really known of the life- 

 histories of the marine food fishes. In the case of every 

 other large food industry much time and thought has been 

 expended from earliest times upon the laws governing the 

 existence and increase of the objects composing the suj^plies. 

 But fish, until lately, we were content merely to capture, 

 quite regardless of their Ijirth and habits. Endeavours to 

 obtain information from fisherfolk and others who are 

 continually in contact with fish have not proved altogether 

 satisfactory, and it was seen that, before the industry could 

 be brought into line with other industries, the matter 

 must be taken in hand in a systematic and comprehensive 

 manner. With this aim in view special investigations for 

 the purpose of elucidating the various problems presented 

 are now being made on lioth sides of the Atlantic. None 

 are more interesting than the series of researches into 

 the natural history of the mackerel, which have been 

 recently undertaken at the request of H.M. Treasury. 

 This important species, with its movements, is one of 

 the most diificult of all the commercial fishes to study or 

 to comprehend. 



Seeing it is a pelagic fish, and has a freely floating egg, 

 one might be led, with some reason, to suppose that it 

 would thereby be enabled to spend its whole life without 

 approaching the land. Fortunately for man, every season, 

 during the warmer portion of the year, it leaves the open 

 sea and migrates towards the shore, when its presence 

 becomes apparent through its surface distribution, the 

 only period when it can be fished for. It frequents the 

 coastal waters in the northern temperate region of the 

 Atlantic. On the Atlantic coast of Europe it extends from 

 Bergen, in Norway, southward to the Straits of Gibraltar ; 

 and throughout the Mediterranean it also occurs, being 

 taken in large quantities on the coast of Spain, the south 

 coast of France, the coasts of Corsica, and in the Adriatic. 

 Koimd the British coasts, the four principal regions for 

 the fisheries are the North Sea to Norfolk, the Channel, 

 and the south and west coasts of Ireland. 



Along with, and contemporaneous with the migration, 

 is the massing together of individuals into the well-known 

 so-called " schools," or shoals. In this way. they swim 

 crowded together during, at any i-ate, a great part of tlie 

 year, and the shoals often contain an immense number of 

 fish. Those pertaining to any particular shoal are usually 

 of about the same size. Schools of large fish and schools 

 of small fish may be present in the same neighbourhood at 

 the same time, but schools of different <\7.f>\ fi^^h do not 



