Shews a bomb arranged with an instantanious lock, and anchored from ten to twenty feet under water, for this purpose when the bomb is arranged with its lock it should be ten or fifteen pounds lighter than its volume water, it will then have a tendancy to mount to the surface but must be held down by an anchor or weight of 20 or more pounds; as the depth of water in all channels, bays and Harbours is known, the line _D_ should before setting out be of such a length as will hold the Bomb from 5 to ten feet under water at low water, it will then be that number of feet added to the rise of the tide at high water, At Slack water it will stand in the position _B_ perpendicular from the anchor at half ebb or flood when the current is strong it will be inclined to _A_ or _C_ where the action of the water on a flat board which is fixed to its bottom at _E_ will keep it in the position here deleniated. On the 5th of June in this year this experiment was made by my desire by Lieutenant Wm Robinson In Dover roads; and the result was as here described—A vessel under sail and striking on the Trigger _F_ of such a Bomb would be instantly blown up, as will be seen in plate the Ninth, _Plate the Ninth_ In this drawing _A_ represents the Brig Dorothea as she blew up near walmer Castle on the 16th of October 1805, the bomb made use of on this occasion had a clockwork lock set to 15 Minuets; the bomb contained 180 pounds of powder; and was coupled by a line of 70 feet in length; to a bomb which was filled with peas and which served as a counterbalance; As the boat run within the Buoy, one was thrown to the Larbord, and one to the Starbord side of the bow, and at the distance of 60 or 80 yards from the brig; as the tide drifted them along the coupling line caught the cable, the pressure of the tide then drove the bombs under her bottom near the Keel, where the explosion taking place she opened in the middle was completely decomposed and in 20 Seconds disappeared, which experiment has proved that wherever such an explosion takes place under the curve of a Vessels bottom; so that the action must be perpendicular through her, certain destruction must be the consequence; _B_ represents a Ship under Sail, _C. D. E_ Bombs anchored as described in the last plate, she moving towards and among them with the risk of contact and destruction; [Illustration: PLATE THE EIGHTH ] _Plate the Tenth_, Figure 1st shews the mode of suspending the bomb to the cork floater _A_; the line _B_ has pieces of cork on it to keep it from sinking; the line _C_ is a brace to prevent the tide driving the Bomb by the doted line to near the surface where it could do no execution: the line _E_ will be longer or shorter in proportion to the draught of water of the vessel to be attached, which will be further explained in figure the _Third_;