II.; MINING. 879 



and thus the inconvenience and loss of time involved in conveying lamps to 

 the lamp-room on bank will be entirely obviated. 



The locking arrangement, as will be seen, is extremely simple, and completely 

 enclosed within the lamp, and protected from injury. 



A number of these lamps can be opened in the time required to open one 

 of the common locks, and a consideration of the accompanying engraving 

 will at once convince the mining engineer of their superiority over every 

 other lamp in use. 



Every further information, and list of collieries where the lamps may be 

 seen in use, can be obtained from S. P. Bidder, 24, Great George Street, 

 Westminster, London, S.W., or from the makers. 



The unlocking of these lamps by the apparatus for the purpose is very 

 simple, and much more easily performed than with the ordinary key. The 

 lock consists only of a piece of flat iron 2f inches by | inch wide and |- inch 

 thick, to the end of which is attached the pin ; this is kept in position by a 

 strong spring underneath it, and projects into the upper rim of the lamp. It 

 is impossible to unscrew the top until this pin is drawn by a powerful eight- 

 bar magnet, the magnetism passing through the brass bottom, and drawing 

 the pin down on the inside. If a large number of these lamps are required to 

 be opened in a short time for cleaning, a set of electro-magnets, worked by a 

 galvanic battery, placed in the lamp cabin is the most convenient arrangement. 



' 3412. Apparatus for showing externally the mixture of gases 

 existing in underground explorings. M. Lemaire Douchy, Paris. 



2. MINING MODELS AND PLANS. 



3413, Working Model of a proposed new system of 

 Hand Drill for mining purposes. Jos. P. O'Reilly. 



The drill consists of the following parts : 



(1.) The bit, made in the model of those employed for artesian borings ; it 



adapts itself by a screw to the 

 . (2.) Barrel. This is of cast steel and tubular, thus allowing the passage 



of a stream of water through the bit into the hole. It is fitted with 



a bearing on its upper extremity on which plays the 

 (3.) Water box, the water passing through holes in the barrel from the 



box. The water box is kept from turning with the drill by 



means of 

 (4.) An armlet or ring passed on the arm, and connected with the box by 



a short connecting rod. The end of the barrel is terminated by 

 (5.) A solid head, changeable, when worn. 



Each blow of the hammer drives the water into the hole with a pressure 

 proportional to the force of the blow, thus clearing away the debris from 4;he 

 bottom of the hole, and keeping the cutting edge cool. The cutting edge, or 

 bit, may be renewed frequently and easily without involving a change of 

 drill, and the carriage of an equal number of drills, as at present. 



3414. Two Plans, illustrating the principal modes of working 

 Coal in the Yorkshire mining district. Walter Rowley, C.E. 



Showing the advantages for economy of working and ventilation of the 

 " Long Wall " system, and the disadvantages resulting from the " Pillar and 

 Stall " mode of working. 



