Contents xxxiii 



PAGE 



heat-unit, composed on this principle, in which the unit of 



length replaces the unit of weight 418 



In terms of the usual British units it is the fathom-degree 

 (Fahrenheit), and in terms of the French units it is the metre- 

 degree (Celsius) ; and, by arithmetical necessity, the fathom- 

 degree (Fahrenheit) is equal to the metre-degree (Celsius) . 419 



No. 18. THERMOMETRIC SCALES FOR METEOROLOGICAL USE. 



(From Nature, August 17, 1899, Vol. LX, p. 364.) . . . 420 



It was known that at the Meteorological Congress, about 

 to be held in Berlin, an attempt would be made to force 

 English-speaking meteorologists to renounce Fahrenheit's 

 scale in favour of that of Celsius, and the object of the paper 

 was to direct attention beforehand to some of the advantages 

 in securing accuracy and in relieving labour which Fahren- 

 heit's scale offers over that of Celsius, when used for meteoro- 

 logical purposes 420 



In the most populous regions of Europe and North America 

 the temperature in winter presents frequent oscillations from 

 one side to the other of the melting-point of ice. If the 

 observer is compelled to use a thermometer which he must 

 read upwards when the temperature is on one side of that 

 point, and downwards when it is on the other side of it, and if 

 he may be called on to perform this fatiguing functional in- 

 version perhaps several times in the same day, it is certain 

 that he will suffer from exhaustion and that the observations 

 will be affected by error . . . ... . . ( .421 



These representations had no effect, though they could 

 not be disputed, and I asked one of the German members 

 how it was that, when they had already a thermometric 

 scale which excluded such avoidable errors, and one which 

 had been devised by a distinguished countryman who was 

 not only a German but a Prussian, they had consented to 

 exchange it for a foreign scale so conspicuously inferior to it. 

 The answer was that it was befohlen, and I was advised to 

 get it befohlen in England. I was surprised by the confession 

 and could only reply that, in my country, we do not do these 

 things in that way. 



No. 19. THE METRICAL SYSTEM. (From the Times, February, 



1903.) 424 



In view of the renewal of the agitation for the universal 

 adoption of the French metrical system, it appears to be 

 opportune to furnish the public with facts regarding it, derived 



