Philip Braham of 6, George-street, Bath, writes; "Reading your issue of the 28th ult. The result of the inquiry concerning the explosion on board the Vesuvius, the remarks concerning the present ignorance of the action of compressed air are too true. In my experiments on it I have found that if animal oil is used to lubricate the compression pumps some of it will get into the compression chamber, and at a certain pressure it will spontaneously ignite, and the heating of the enclosed air, will considerably raise the pressure. I did hope to find that this had been noticed by those engaged in the late important torpedo experiments."