Charles William Pasley to Faraday   12 January 1839

Chatham the 12th of Jany | 1839

My dear Sir,

I am very much obliged to you for your letter of yesterday. I have got a Battery of 10 cells with porcelain tubes, which cost 4 Shg apiece besides the expense of Carriage and are perfectly rotten & worthless and 3-4ths broken. We have replaced them with Membranes costing 2d apiece. In trying the com‑parative strength of the detonating powders, we first used only 2 cells, which having failed, we used 3 cells, which fired the detonating powder, but not common gunpowder. 4 fired the common Gunpowder. In our experiments in the Medway, we used all our cells, & as our men are Artificers I have ordered 10 more copper cells &c, complete to be made, to double the power of our Battery¹. The mode we prepare our charges for immersion is this

We inclose our wires in tape sewed round, and covered with water proof composition, composed of pitch, bee's wax and tallow. The ends of these wires are represented by w, w. They are led down through a wooden top into a cell CC forming a recess in a water proof cylinder, which if we should ever attack the Royal George, will be of very large dimensions, but this cylinder is small in the annexed sketch. The wooden top is shaded. The wires pass through holes in it purposely made large enough not to jam or confine it tight, which we found in some of our previous experiments prevented the ignition of the charge. The two wires are bent at right angles towards each other below the wooden top or lid, to which they are screwed or nailed up by the screws SS. The top of the wooden lid has a water proof coating of fine canvas fixed to it, from which rise two canvas collars coated with water proof composition and tied close round the wires near the points W, W, in the former figure. This canvas work before it is fixed upon the wood is represented by the figure opposite

B is a bag, rendered water proof by a composition of rosin & tallow, containing the powder for firing the great charge, which it does by bursting through the cell into the great charge between the points m n, in the first figure. If the explosion of 2 or 3 ounces contained in B should fail no harm is done. The bag B is covered with waterproof composition. The platinum wire pierces it from one side to the other, being soldered to the extreme ends of the copper wires, pointing towards each other, as I said before. This platinum wire passes through the middle of a small paper cartridge (P) containing the detonating powder of nitre sulphur & carbonate of Potash. This little cartridge represented in the first figure is 3/8th inch in diameter, & surrounded by gunpowder on all sides. The neck of the bag B in which it is introduced is only 1 inch in diameter though it looks larger in the figure, and goes into a cell or groove cut in the wooden top. This day was our most prosperous experiment. We put 100 feet of the copper wires under water with a charge also under water, but there were 470 more of the wires on shore. On trying to explode the whole length 570 feet it failed, but on trying to explode it by the wires shortened to 440 feet it succeeded. We mean next to cover the whole of the wires with the same tapes and water proof composition and to try 450 feet entirely under water, first in a pond & afterwards in the Medway. If 10 cells will not succeed, we will increase the number until it does. 450 feet is the longest wires safety requires even for the largest charges in subaqueous explosions. I have no doubt now of our success. We find that the wire one fifth of an inch in diameter, which I think you recommended, either personally or in your manipulations², will fire gunpowder at twice the distance of the common bell wire about 1/16th of an inch in diameter which we also used. The way we arrange our wires is thus. We attach them to a rope on contrary sides of it, and bind them round with small cord as in the annexed figure,

in which the tape coating covering round the wire is black, the small cord is also black. In this form the wires coil up easily with the rope; but before we fixed them to the rope, the thick wires were very stubborn and intractable.

It was suggested to lay the wires in the seams of the rope in a spiral going round and round, but this mode though it looks much more snug increases the length of the wire too much.

Yours very faithfully | C.W. Pasley