APPENDIX 237 



use, the much less convenient Fahrenheit and Reaumur scales 

 are still often employed in ordinary life. 



The relationships between the three scales is simple, it being 

 only necessary to remember that the interval between the 

 melting-point of ice and the boiling-point of water under a 

 barometric pressure of 760 mm. of mercury is divided into 

 100° on the Centigrade, 180° on the Fahrenheit, and 80° on 

 the Reaumur thermometers; and that while the scales com- 

 mence at the lower temperature on the Centigrade and Reaumur 

 thermometers, on the Fahrenheit instrument it begins at a 

 point 32° below the melting-point of ice. 



Hence 



° C. = f ° R. = I (° F. - 32), 



or ° F. = I- ° C. + 32 = f ° R. + 32, 



or ° R. = 4 ° C. = J (^ F. - 32). 



On the continent of Europe many thermometers are 

 graduated on one side in Centigrade, on the other in Reaumur 

 degrees. With such an instrument an easy way of obtaining 

 the temperature in Fahrenheit degrees is to add the read- 

 ings in Centigrade and Reaumur degrees together, and then 

 add 32. 



Units of Lengthy Area, Volume, and Weight. — Our British 

 system of weights and measures is absurdly cumbrous, com- 

 plex, and inconvenient, and it is to be hoped that the whole 

 of the civilised world will eventually resort to some simple 

 and rational method of expressing lengths, areas, volumes, 

 and weights. In agriculture, perhaps more than in other 

 branches of commerce, English units are inconsistent, for 

 there are such anomalies as selling grain nominally by volume 

 (bushels and quarters) and then fixing definite weights, which 

 necessarily differ with various products, for these volumes, and 

 which are so arbitrary that they differ in various parts of the 

 country. 



Then even in our weights there are peculiar anomalies ; e.g., 

 the hundredweight is 112 lb. in England, though usually 



