480 Rev, B. Powell, [Feb. 26, 



The spring-curtain of this lock may be adapted to almost any 

 other, and is particularly recommended for street-door or " latch " 

 locks, as they are called, which are very liable in such towns as 

 London to be spoiled, or put out of order, by the action of the air 

 and dirt upon them. Mr. Hobbs adds this curtain to his latch 

 locks for a trifling extra charge, the cost of making it being insig- 

 nificant ; and it supersedes the necessity for an external " scutcheon" 

 on the key-hole, which seldom keeps long in action, and is not so 

 effectual as this self-acting curtain. 



Mr. Denison also exhibited three small bells, made by Mr. 

 Mears : one of the same metal as the great bell of Westminster 

 which he is now re-casting ; another, with the addition of as much 

 silver as would amount to 1 cwt. and cost £500 in a 16-ton bell; 

 and the third with rather more. These bells clearly bore out the 

 statement made in the lecture on bells last year, that the tone 

 would not be improved by adding silver, of which also no trace has 

 been found in any old bell-metal that has been analyzed. 



[E. B. D.] 



WEEKLY EVENING MEETING, 

 Friday, February 26. 

 The Lord Wensleydale, Vice-President, in the Chair. 

 Rev. Baden Powell, M.A. F.R.S. F.G.S. F.E.A.S. 



SAVILIAN PKOF. OF GEOMETRT, OXFORD. 



On Rotatory Stability; and its Applications to Astronomical 

 Observations on board Ships, 



The subject of rotatory motion, especially when taking place under 

 those combinations which are presented in the gyroscope, or free 

 balanced revolver, has attracted much attention at the present day ; 

 and though the primary mechanical principles bearing upon it had 

 been long since understood and acknowledged in theory, yet the 

 practical results to which they might lead had been so little con- 

 sidered, that when first tangibly exhibited they excited unbounded 

 surprise. 



Even some scientific persons were at a loss to account for them, 

 or sceptical as to their real nature ; especially when they witnessed 

 the wonderful results obtained by M. Foucault, apparently sub- 

 verting the laws of equilibrium, and looking more like magic or 

 legerdemain than sober philosophical experiments. Yet while 



