Moving Weights and Iron Bars 1 1 1 



Philosophical Transactions, namely one by Dr. James^ 

 Parsons in 1743, a second by Mr. W. Bell in 1793 on a 

 two-horned Rhinoceros, dissected at Bencoolen, and a third 

 by Mr. H. L. Thomas in iSoi. 1 



The members present at the 25th meeting (Dec. 2oth) 

 discussed a recent report of the Commissioners appointed 

 to enquire into the application of iron to railway structures, 

 Mr. Rennie reported that experiments, conducted by and 

 for them, had shown that a load traversing a bar produced 

 a greater deflection than if it were placed on the middle 

 part, and that as the velocity of the traversing weight 

 increased, so did the deflection ; that corresponding with 

 a rate of thirty miles an hour being more than double of the 

 amount produced by a ' dead weight.' The greatest deflec- 

 tions also were not in the middle but towards the extremity 

 of the bar most remote from the point of access, a result 

 which had not been anticipated by the Commissioners, but 

 had been predicted by Professor Airy, the Astronomer Royal. 



1850. At the 26th meeting (Jan. 24th), Dr. Hooker's 

 imprisonment in Sikkim was mentioned, and Lord Dalhousie 

 was said to have taken steps to secure his release. 2 



Sir J. Richardson gave an account of rich deposits of 

 native copper in the neighbourhood of Lake Superior,* 



1 Phil. Trans, xlii. p. 523 ; id. 1793, part i. p. 3 ; id. 1801, p. 145. 



2 Dr. Hooker was then travelling with Dr. Campbell, the superintendent 

 of Darjiling, which was purchased about 1840 from the Rajah of Sikkim. 

 The story, a rather complicated one, is told in chapters xxv. and xxvi. 

 of the Himalayan Journals. They were arrested on Nov. 7th, 1849, at 

 their camp when returning from an attempt to travel hi Thibet, and were 

 detained till Dec. 24th. The motive was the hope of extracting from Dr. 

 Campbell, who was at first violently assaulted, a treaty favourable to the 

 ambitious designs of the Rajah's chief minister. Accidental circumstances 

 prolonged their captivity, which ended when the chief offender found that 

 Lord Dalhousie was not to be trifled with, but for a time their lives were 

 evidently in danger. 



3 The metal occurs " in ' trappean ' rocks and their associated conglome- 

 rates (ascribed by Whitney to the Lower Silurian Period) in Michigan on 

 the southern shore of Lake Superior. . . . Masses of nearly pure copper, 

 weighing over 400 tons, have been met with. . . . The bulk of the produce 

 is, however, obtained by stamping and washing rock containing from to 

 4 per cent, of copper." J. A. Phillips and H. Bauerman, Elements of 

 Metallurgy (1887), page 399. (They are late Precambrian in age.) 



