PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 389 



temperature are the dangerous vapors given off? and that is shown by this 

 instrument. 



The Secretary inquired if the proportion in which the vapor was mingled 

 witii the atmosphere, was not important; it was generally believed that 

 hydrocarbons were explosive in all proportions between one in three and 

 one in fifteen. Now, do these instruments provide properly against vari- 

 ations in the quantum of air allowed to find access in the warm oil and 

 mingle with the vapor? 



Mr. Page and Mr. Brace thought the instrument would always detect 

 within reasonable limits the dangerous character of an oil. 



Mr. H. J. Callo. — As all of these oils give off vapors below their boiling 

 points, only more slowl}', will not these vapors accumulate when oils are 

 stored in close cellars or roonis, and thus may we not have explosions from 

 oils which will not appear to be dangerous when tested by this pyrometer? 



Mr. Churchill. — That is really the objection, in a scientific point of view, 

 to this instrument. Still, from experiments that I have made, I think 

 the instrument will show very well the comparative safety of oils. 



The whole evening was spent in the discussion of these absorbing topics, 

 and the regular subject, " Paper and its Uses" was not reached. This 

 subject was accordingly appointed for the next meeting, which is to be 

 held a fortnight hence, and the Association adjourned. 



Thomas D. Stetson, Secretary. 



American Institute Polytechnic Association, \ 

 November 13, 18(52. ) 

 The Chairman, S. D. Tillman, Esq., presiding. 



Door Locks and Explosions. 



Mr. Churchill. — This is one of Pye's patent door locks; I have had one a 

 year; it has been subjected to pretty rough usage and is a good lock still. 

 It cost a dollar, and the inventor says that it cannot be picked. 



Mr. Wm. H. Butler. — It is a good cheap lopk, but claiming that it cannot 

 be picked is offering us a little too much — an unpickable lock for one dollar. 

 All locks of this character Avhen placed upon a door may be opened without 

 picking. It is necessary only to introduce a thin screw-driver or blade 

 between the edge of the door and the jamb and press the bolt back. That 

 can be done by any sneak thief, who has not the skill to be ranked araong'l 

 burglars. I believe that burglars do not recognize those boyish and un- 

 skillful tlneves as belonging to their fraternity. 



Mr. Stetson. — I would ask Mr. Butler if the statement on the card is cor- 

 rect ? It says this lock cannot be picked. 



Mr. Butler. — I should say that it would take one of Mr. Chubb's appren- 

 tices about fifteen minutes to pick this lock if he had it on the bench before 

 him, but if he was obliged to operate through a door it might be difficult. 



Mr. Eowell. — The idea has frequently occurred to me — why should we 



