Sir J. Dewar and Mr. K. A. Hadfield. Effect of [Nov. 24, 



observed on the other. When S represents areas of whole sun- spots or 

 of umbrae, the agreement between observed and calculated ranges is 

 nearly though not quite as good, especially in horizontal force, as when 

 S represents Wolfer's sun-spot frequencies; but when S represents 

 areas of faculae the agreement is much inferior, especially in years of 

 sun-spot maximum. The mean differences between the ranges calcu- 

 lated from Wolfer's frequencies, and from either the spot areas or the 

 umbrae is considerably less than between any one of the three sets of 

 calculated ranges and the observed ranges. Also the differences 

 between the observed ranges and those calculated from Wolfer's 

 frequencies nearly always possess the same sign at Kew and Falmouth. 

 Both phenomena point to the conclusion that the differences between 

 observed magnetic ranges at individual stations, and those calculated 

 from any of the above measures of solar disturbance, though small, 

 cannot be regarded as wholly fortuitous. 



" The Effect of Liquid Air Temperatures on the Mechanical and 

 other Properties of Iron and its Alloys." By Sir JAMES 

 DEWAR, F.K.S., Hon. M.I.C.E., and KOBERT ABBOTT HADFIELD, 

 M.I.C.E., President elect Iron and Steel Institute. Keceived 

 November 24, Eead December 8, 1904. 



As many iron alloys have shown anomalous results in their physical 

 behaviour at ordinary temperatures, it became advisable to ascertain 

 the exact effect of very low temperatures upon such bodies, and, 

 accordingly, a series of tests were carried out on standard iron and 

 iron alloyed with other elements, the specimens being selected from 

 a large collection made by one of the authors, which is located at 

 the Hecla Works, Sheffield. In the course of the enquiry some 

 500 specimens have been examined, and the detailed description of 

 each test will appear later on in a special Monograph. In the meantime 

 the more important results are submitted to the Koyal Society. 



For the purpose of the experiments, the irons were taken in the 

 form of forged bars, and the iron alloys in the form of cast ingots 

 2J inches square. They were then carefully heated to the required 

 forging temperatures and reduced to rods J-inch diameter, and from 

 these rods finished test-bars 0-180 inch diameter were accurately 

 machined to the following sketch : 



