The fibre, Sir Frederick Abel says, is as effectual for closing the breeches of big guns so as to prevent the passage of gas, as for ensuring safety, in the same way, for miners' lamps. In these last, it had for a long time been found very difficult to get a good joint between the metallic and the glass parts of the safety lamp, and a great many different materials were tried for filling these joints in such a way that air should not be able to pass through. In many cases, the air was contaminated with a certain amount of gaseous material which would be likely to render the whole explosive, and if this got through the joint between the glass and the metal, there would be very serious risk of explosion. After a great number of substances had been tried and found unsatisfactory, some hundreds of experiments were made by Sir Frederick Abel and Sir Warington Smyth, with asbestos washers, which, in the end, were found to maintain their condition most admirably. With regard to closing the breeches of big guns, we are informed also on the authority of Sir Frederick Abel, that the only contrivance which could be called an approach to a perfect arrangement, was one devised by a French artillery officer, M. Dubange, which consisted of a kind of pad of asbestos fibre attached to the breech-closing arrangement. This, from its mineral nature, was nearly indestructible, and, consequently, lasted without material deterioration for a great length of time, notwithstanding that it was subjected to the enormous pressures which are now developed in the bores of very heavy guns. In connection with the Whitehead torpedoes, we learn from the same authority, that in these and other similar receptacles, within which charges of wet gun cotton are enclosed, the use of asbestos is now found to overcome a great difficulty. The vessels containing the damp cotton have to be soldered, in order to keep them perfectly air-tight, and thus prevent the water from escaping; and in order to do this, with anything approaching safety, the space between the gun cotton and the metal surfaces which have to be soldered, were formerly filled with damp felt wads or discs. This answered the purpose; but Sir Frederick Abel states that it was found after they had been stored for some time, that the effect of the moisture on the felt was to cause it to undergo a kind of decay or fermentation, resulting in the formation of gas to such an extent that the vessels were distended, and threatened to burst, and sometimes actually did burst with considerable violence. Asbestos millboard was then substituted for the felt, and the difficulty and danger were then removed; gas was no longer evolved, whilst the operation of soldering could be performed with safety, the material remaining perfectly unaltered.