740 



SEC. 16. GEOLOGY AND MINING. 



North of England Institute of Mining and Mechanical 

 Engineers. 



3409. Rudiments of Apparatus constructed by Sir Hum- 

 phry Davy during his researches on the Safety Lamp. 



The Royal Institution of Great Britain. 

 Phil. Trans. 1815 to 1817. 



3409a. Mining Lamp. 



M. Breguet, Paris. 



3410. Specimen of the General Map of the Belgian 

 Mines (a chromolithographic sheet, 46 m by 60 m , exclusive of 

 the margin, with a MS. or printed note). 



This map, to a scale of one five thousandth, represents a section 

 </)f the coal basin comprised between two horizontal planes at the 

 levels of 140 and 190 below the sea. It is executed by order of 

 the Public Works Department, and will be completed in six or 

 seven years. J. van Scherpenzeel Thini, Liege. 



3411. Bidder's Patent Magnetic Lock for Miner's Safety 

 Lamps. 



All previous inventions h ave failed* to prevent the men from opening their 

 lamps with forged keys or other implements, and it is well known that a large 

 proportion of explosions have occurred from this dangerous practice. It is 

 evident that safety can only be secured by rendering the opening of the lamp 

 impossible by any means, short of its destruction, which are available to the 

 colliers. 



This important desideratum is supplied by these lamps, which are secured 

 by a self-locking catch, which comes into action when the bottom of the lamp 

 is screwed home, and it can only be opened by means of a powerful and 

 costly magnet, which is kept in a strong box, under lock and key, in charge 

 of the lamp cleaner. 



Anotber magnet may be put under the care of a fireman in the pit, 

 whose duty it will be to re-light lamps which have been put out by accident, 



