Chagrined a little that we have been hitherto able to produce nothing in this way of use to mankind, and the hot weather coming on, when electrical experiments are not so agreeable, it is proposed to put an end to them for this season, somewhat humorously, in a party of pleasure, on the banks of Skuylkil. Spirits, at the same time, are to be fired by a spark sent from side to side through the river, without any other conductor than the water--an experiment which we some time since performed, to the amazement of many. A turkey is to be killed for our dinner by the _electrical shock_, and roasted by the _electrical jack_ before a fire kindled by the _electrified bottle_, when the healths of all the famous electricians in England, Holland, France, and Germany, are to be drunk in _electrified bumpers_, under the discharge of guns from the _electrical battery_. Franklin's electrical battery consisted of eleven large panes of glass coated on each side with sheet lead. The electrified bumper was a thin tumbler nearly filled with wine and electrified as a Leyden jar, so as to give a shock through the lips. Franklin's theory of the manner in which thunder-clouds become electrified he found to be not consistent with his subsequent experiments. In the paper which he wrote explaining this theory, however, he shows some knowledge of the effects of bringing conductors into contact in diminishing their capacity. He states that two gun-barrels electrified equally and then united, will give a spark at a greater distance than one alone. Hence he asks, "To what a great distance may ten thousand acres of electrified cloud strike and give its fire, and how loud must be that crack? "An electrical spark, drawn from an irregular body at some distance, is scarcely ever straight, but shows crooked and waving in the air. So do the flashes of lightning, the clouds being very irregular bodies. "As electrified clouds pass over a country, high hills and high trees, lofty towers, spires, masts of ships, chimneys, etc., as so many prominences and points, draw the electrical fire, and the whole cloud discharges there. "Dangerous, therefore, is it to take shelter under a tree during a thunder-gust. It has been fatal to many, both men and beasts. "It is safer to be in the open field for another reason. When the clothes are wet, if a flash in its way to the ground should strike your head, it may run in the water over the surface of your body; whereas, if your clothes were dry, it would go through the body, because the blood and other humours, containing so much water, are more ready conductors. "Hence a wet rat cannot be killed by the exploding electrical bottle [a quart jar], while a dry rat may." In the above quotations we see, so to speak, the germ of the lightning-rod. This was developed in a letter addressed to Mr. Collinson, and dated July 29, 1750. The following quotations will give an idea of its contents:--