September 2, 19 15] 



NATURE 



For instance : " Use the two tops of your fly-rod 

 alternately," he advises, and the advice is very 

 obviously sound. But some of us, alas ! have 

 never thought of it before, regarding- the second 

 ip as merely a spare one for emergencies. And 

 I I we have talked to each other with conviction 

 about split cane getting "tired " after continuous 

 use for some time ! This is a small matter, but 

 there are plenty of similar casual hints which will 

 come forcibly home to a good many of us who 

 have long passed out of our novitiate. 



In the other chapters Mr. Shaw deals with 

 the fisherman's entomology, now a fairly well- 

 ploughed field, with pisciculture and the natural 

 history of trout, of which much the same may be 

 said, now that there is a trout farm in almost 

 (Very likely valley of springs, with the senses of 

 I rout, particular attention being paid to their 

 vision, and especially to how far they can see 

 behind them, a point which so far as we remember 



^^ane^oFTroi^^^ 



F:g. 2.— From "The Complete Science of Fly Fishing and Spinning, " 

 by F. G. Shaw. 



no other writer has tackled— but it is one of im- 

 portance, as every man who has stalked a fish on. 

 a " shy " day will allow. 



There are also chapters on salmon and salmon 

 scales. In the last Mr. Shaw devotes a great 

 many words to labouring what seems to us an 

 odd objection to the usual interpretation of what 

 is called the spawning mark, which is, of course, 

 that a fish has spawned in some previous year. 

 Mr. Shaw apparently wants evidence of the act 

 Itself before he will admit that salmon ever spawn 

 more than once. The spawning mark, in his 

 A-iew, would, we gather, be evidence of a visit to 

 'resh water for the purpose of spawning, but not 

 ' ' essarily that the purpose was satisfactorily 

 (omplished, the ova being duly fertilised and 

 safely stored in the redds. So far nobody would 

 quarrel with him, we expect, but, unless we wrong 

 him, he seems to find in the spawning mark 

 ' evidence that the spawning purpose has not been 



^ NO. 2392, VOL. 96] 



carried out, the eggs being voided in vain or re- 

 absorbed. A fish so cheated "will return again 

 and again until it has satisfactorily achieved its 

 life's purpose." We fear we cannot produce 

 scales from a fish marked in the act of spawning 

 and recaptured later, to convince Mr. Shaw. Per- 

 haps he can produce scales from the necessary 

 percentage of unfortunate fish which have been 

 found voiding their ova in vain to convince us? 

 At present our inclination is towards the current 

 view of the spawning mark and its significance. 

 There are other points in the book in which our 

 view would not coincide with Mr. Shaw's (incident- 

 ally we have found some scarcely excusable mis- 

 prints), but on the whole we must own to having 

 studied him not without pleasure and profit. 



THE TESTING OF CHRONOMETERS.^ 



IN his recently issued report on the testing of 

 chronometers at Geneva, M. Raoul Gautier, 

 who has been in charge of the department for 

 twenty-five years, takes the opportunity of review- 

 ing briefly the successive alterations and improve- 

 ments that have been introduced in the methods 

 of testing, and the happy results that have fol- 

 lowed from the maintenance of a high standard. 

 We may take this same opportunity of con- 

 gratulating the distinguished director of the 

 observatory on the useful work accomplished, 

 and with which the name of Gautier has been so 

 long and so honourably connected. 



Nearly a century has passed since Alfred 

 Gautier combined the duties of the director of the 

 observatory with those attached to the Chair of 

 Astronomy. But even before that time Geneva 

 was bidding for the watch trade and fully alive 

 to the advantage that would accrue from an in- 

 crease in the accuracy of performance. In 1789 

 prizes were offered by the local Society of Arts for 

 a notable improvement in the rate of pocket 

 watches, but the prize remained unawarded, for 

 the ambitions of the judges were so much in ad- 

 vance of the abilities of the maker that the 

 standard was not attained. In framing more 

 modest requirements, it was stipulated that the 

 daily rate of the watch should not vary more than 

 one minute during a trial of a month in a vertical 

 and horizontal position, and not more than two 

 minutes when worn for the same period. Two 

 watches were submitted, and one was stated to 

 have fulfilled the conditions. 



These were humble beginnings, and the dis- 

 turbed state of Europe during the Napoleonic wars 

 prevented anything like an annual competition, 

 which the local Society of Arts proposed to hold. 

 But progress must have been rapid, for in 1816 the 

 limit of variation of rate was reduced to three 

 seconds in twenty-four hours, whether the watch 

 was at rest or carried in the pocket. For the first 

 time we find a temperature factor mentioned : the 

 watch was to be kept in a constant temperature of 

 25° Reaumur, and it was not till much later that 

 any serious attempt was made to remove the ill 



1 "Rapport smr le Concours de Riglage de Chronomfeires." Par M. le 

 Prof. Raoul Gautier, Directeur de I'Observatoire de Geneve. 



