1 858.] Mr, E. B. Denison, on Improvements in Locks. 475 



porary negative state whilst under induction, now to assume the 

 positive condition. It would be of no use trying the flame on the 

 other side of the sulphur plate, as then its action would be to dis- 

 charge the gutta-percha, and destroy the induction altogether. 



When several plates were placed in the inductive field apart 

 from each other, subject to one common act of induction, and 

 examined in the same manner, each was found to have the same 

 state as the single plate described. It is well known that if several 

 metallic plates were hung up in like manner, the same results would 

 be obtained. From these and such experiments, the speaker took 

 occasion to support that view of induction which he put forth twenty 

 years ago,* which consists in viewing insulators as aggregates of 

 particles, each of which conducts within itself, but does not conduct 

 to its neighbours, and induction as the polarization of all those 

 particles concerned in the electric relation of the inductric and iu- 

 ducteous surfaces ; and stated, that as yet he had not found any 

 facts opposed to that view. He referred to specific inductive capa- 

 city, now so singularly confirmed by researches into the action of 

 submarine electro-telegraphic cables, as confirming these views ; 

 and also to the analogy of the tourmaline, whilst rising and falling 

 in temperature, to a bar of solid insulating matter, passing into and 

 out of the inductive state. 



[M. F.] 



WEEKLY EVENING MEETING, 



Friday, February 19. 

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



Edmund Beckett Denison, Esq. M.A. Q.C. M.R.I. 



On some of the Improvements in Locks since the Great Exhibition 



0/1851. 



It is impossible to give an intelligible abstract of the mechanical 

 details of this lecture without drawings ; but the substance of it 

 will be found, among other matters relating to locks, in the second 

 edition of Mr. Denison's book on Clocks and Locks,'\ reprinted, 

 with additions, from the Encyclopedia Britannica. 



He proposed to take up the subject where it was left by the late 



* Phil. Trans., 1837. 



t Published by A. and C. Black, Edmburgh ; and sold at Dent's, 61, Strand, 



