No sooner do we enter, and pay our shilling at the door, then “bang, bang, bang” goes the gong—a Lecture on “a New Method of Blowing-up Sunken Vessels” is announced. Do our young friends recollect the circumstance of the sinking at Spithead of one of our largest men-of-war, the “Royal George?” a very beautiful model of which is to be found in the Museum for Shipping and Maritime Apparatus; the circumstances are so well known, that we will presume you not to be ignorant. Well, some years after the accident, a plan was projected by Colonel Pasley, of the Royal Engineers, for raising the guns and other valuables which were, of course, carried down with the ship; this plan was founded upon the well-proved law of electricity—that if the wire which conducts that wonderful agent be intercepted by a short piece of platinum wire, exceedingly small in diameter, and placed within a membrane impervious to water, and surrounded by a charge of gunpowder, a partial impediment to the passage of the electric fluid necessarily takes place, and the small platinum wire is made red-hot—and my young friends well know that if a piece of red-hot wire be placed in contact with gunpowder, that it will readily explode; hence, if a sufficient charge be placed within the vessel, the explosion would separate the timbers of the ship, and, by their floating properties, they would rise to the surface, and leave behind any great weight, such as guns, &c.; by the aid of the diver, then, they are attached to air cylinders, and floated to the surface. But to accomplish this, there are many reasons why more simplicity should be employed, and for this purpose the Lecture we allude to was given, embracing as it does a more simple plan. The invention is patented by a gentleman named Trestrail, of Southampton, and is as follows:—An air-tight vessel is fitted up with a coil of “fuse,” as it is called, consisting of a kind of flexible tube filled with gunpowder, and coated with a pitchy substance, to prevent its coming into contact with the water, which would, you know, destroy its explosive condition. This fuse will continue to burn under water for almost any distance, and was formerly used for the purpose of blasting rocks, blowing up sunken vessels, &c.; but the adaptation of Mr. Trestrail differs from this method, from the material or fuse being in the case, which is to raise the object from the bottom, by generating the gases contained in gunpowder, which gases are nitrogen, carbonic oxide, sulphurous acid, deutoxide of nitrogen, and carbonic acid gas, in different proportions. But this is going from our subject—you must read Chemistry to understand this. However, these gases force the water from the cylinders, and of course take its place; then, you know that the specific gravity or weight of the gas is so much less than the same bulk of water, that it has a buoyant property and rises to the surface, bringing with it whatever, in the judgment