He had one immense advantage over the wise men of England and France, in the superior dryness of our air, which greatly favors such experiments. Almost any one of the young Americans who will read this book has tried the experiment of exciting electricity by shuffling across a Brussels carpet on a dry floor, and then lighting the gas from a gas-jet by the spark. But when you tell an Englishman in London that you have done this, he thinks at first that you are making fun of him. For it is very seldom that the air and the carpet and the floor are all dry enough for the experiment to succeed in England. This difference of climate accounts for the difficulty which the philosophers in England sometimes found in repeating Dr. Franklin's experiments. When it came to lightning and experiments about that, he had another very great advantage; for we have many more thunder-storms than they have. In the year 1752, when Mr. Watson was very eager to try the lightning experiments in England, he seems to have had, in all the summer, but two storms of thunder and lightning. Franklin made his apparatus on a scale which now seems almost gigantic. The "conductor" of an electrical machine such as you will generally see in a college laboratory is seldom more than two feet long. Franklin's conductor, which was hung by silk from the top of his room, was a cylinder ten feet long and one foot in diameter, covered with gilt paper. In his "Leyden battery" he used five glass jars, as big as large water-pails,--they held nine gallons each. One night he had arranged to kill a turkey by a shock from two of these. He received the shock himself, by accident, and it almost killed him. He had a theory that if turkeys were killed by electricity, the meat would perhaps be more tender. He acknowledges Mr. Collinson's present of the glass tube as early as March 28, 1747. On the 11th of July he writes to Collinson that they ("we") had discovered the power of points to withdraw electricity silently and continuously. On this discovery the lightning-rod is based. He describes this quality, first observed by Mr. Hopkinson, in the following letter:-- "The first is the wonderful effect of pointed bodies, both in _drawing off_ and _throwing off_ the electrical fire.