1867.] The Ventilation of Coal Mines. 195 



the explorer : having advanced the 40 or 50 yards, which is the 

 length of the flexible pipe, it is unscrewed and attached to the next 

 joint, so that he breathes the pure air passing through them even 

 in the midst of an atmosphere of death. 



M. Galibert's respirating apparatus for enabling any one to 

 penetrate dangerous gases, such as carbonic acid, is so much 

 more simple that it must be briefly described — especially as it has 

 met with the approval of the Academy of Sciences of Paris. A 

 reservoir of air is carried on the back, fixed by means of braces and 

 a waist-belt. This reservoir is a bag formed of an exterior envelope 

 of linen, sufficiently strong to resist the roughness of the rocks or 

 coal, with which it may come in contact. Upon this is laid a* much 

 finer linen cloth, each cloth being covered with repeated layers of 

 india-rubber, which causes them to adhere very closely. The 

 capacity of the bag may be varied ; but M. Galibert usually makes 

 it to hold 140 litres (1 *760 to the pint), which will allow a man to 

 remain for thirty-five minutes in the most deleterious gases without 

 inconvenience. From this bag tubes extend over the shoulders ; 

 and they are provided with a nose and a mouth piece, which are 

 properly secured. The man with this apparatus adjusted takes the 

 air from the reservoir, and respires again into it. He breathes the 

 same air many times over without experiencing any inconvenience. 

 He knows when it is time for him to think of retreat, as his 

 respirations become more frequent ; but after the first warning he 

 can remain seven or eight minutes without danger. This apparatus 

 occupies but half-a-minute to prepare and adjust ; it requires no 

 instruction for its use ; and with it any one can remain half-an-hour 

 in the level of a mine filled with " choke-damp," and thus probably 

 rescue many who would otherwise perish. M. Galibert states that, 

 from experiments made with his apparatus, he finds that the 

 quantity of air absorbed is about nine litres per minute when in 

 repose ; and in walking at the rate of six kilometres (between three 

 and four miles) an hour, is rather more than ten litres a minute. 



We must briefly refer to another form of apparatus for pene- 

 trating inflammable and irrespirable gas in collieries, and invented 

 by M. Bouquayrol, engineer to the Aveyron collieries in France. 

 This apparatus consists of a reservoir, which is made of thick iron 

 plates, capable of resisting pressures of twenty-five and forty 

 atmospheres. The air is injected by means of very ingenious pumps, 

 in which the pistons are fixed and the cylinders move. When 

 charged with air, the apparatus is placed on the back like a knap- 

 sack. A kind of mechanical bellows is placed on the top of the 

 reservoir, allowing the air, although at a very great pressure, to 

 enter the lungs at the ordinary pressure. A little exterior valve, 

 formed of two leaves of india-rubber, which are held together 

 by the pressure of the atmosphere, opens itself to let out the 



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