Charles William Pasley to Faraday   9 February 1839

Chatham the 9th of | Feb. 1839

My dear Sir,

The preparations that I made for securing the Copper wires to a rope &c, have been successful beyond our hopes¹. Every thing being covered and paid over with pitch &c, each wire in its tape coat, the rope paid over separately then another broad tape covering it, served with hemp yarns &c, all this having rendered our apparatus completely impervious to water, though capable of being coiled up and reeved out from a boat, we fired a charge at the bottom of the Medway from a boat at the distance of 400 feet by 10 cylinders only. I had provided 20 cylinders in readiness, intending if it failed, to add a pair more and make a new trial until it succeeded, and from my former experiments with the wires secured against contact, but not impervious to water, I really thought that 20 would have been required. The dryness of the wires therefore appears to be of very great importance. They were nearly 1/5th inch in diameter.

With common bellrope wires 1/16th inch in diameter we could do nothing. 20 cylinders would not fire a charge with them until we reduced the length from 500 to 240 feet. Thus the power of conducting of the small to that of the large wires appears to be as one fourth, rather less than the proportion of their respective diameters; but I think if I recollect rightly, Mr Daniell told me that the power was as the square of the diameter, which would be as 1 to 9 only. I think this must be a mistake, either in his rule or in my having misunderstood him.

My experiment in the Medway was with a very small charge only, as I do not choose to invite spectators to an exhibition with any chance of failure. But I will have another in the course of a fortnight, of which I will give due notice, to sink a cask loaded with gravel to represent a wreck, send a charge of 30 lbs of Powder down to it, and blow it to pieces by the Voltaic Battery from a boat at 500 feet. In short it will be my proposed attack on the Royal George in miniature. The water will be thrown up in a jet and the cask being of fir will come up in Fragments to the surface. I will let you and Mr Daniell know in due time & hope you will dine with us. Today I have laid the same Apparatus underground to fire a Mine by the Voltaic Battery for the first time, at 500 feet at which I have invited the officers of the Garrison to be present.

I remain | My dear Sir | Yours very faithfully | C.W. Pasley

P.S. the Mine failed owing to the negligence of the workman, who soldered the platinum wire to the two copper wires. He had left it too long and it broke, as we ascertained, so that there was no circuit. On Monday I will try the Mine again[.]