234 Proceedings of the Royal Society of Victoria. 



by a graduated wedge of bell-metal. The lengths are found to 

 be as follows (reduced to a temperature of 62° Fahr) : to 

 100=1199-9749 inches, to 50 = 599-9647, 50 to 100 = 600-0103. 



The old range measured at 66 and 100, when first put up, 

 792-18 inches and 1200-20 inches; but just before removal the 

 measure was 792-22 and 1200-32. 



The stability of such ranges is found to be extremely good, 

 but not absolutely perfect, for a secular change in the old range 

 of 0-12 inches took place. This, however, is of no moment, as no 

 standard measures are absolutely correct or perfectly permanent ; 

 the only point necessary is that the value of the standard should 

 be obtained from time to time, and persons using the test should 

 always obtain the value from the latest measures. 



For very accurate comparisons and for determining expansions 

 in high temperatures, a heavy iron block, with reading microscope, 

 has been made, l)y which variations of yoVo ^^^^ easily measured. 



