If now I connect my two hands, one with the inside and the other with the outside of the jar, this stored energy will strike me with a force equal to all the energy I have previously expended in pressing against the wheel, minus the loss in heat. If I did it for a long enough time this electrical spring would be wound up to such a tension that the recoil would destroy life if one put himself in the path of its discharge. If all the heat in the first case were gathered up and made to bend a stiff spring, and one should put himself in its way when released, this mechanical spring would strike with the same power that the electrical spring did when the Leyden jar was discharged. This statement assumes that all the energy in the second experiment was stored as electricity in the jar. You will be able to see from the above illustration that heat, electrical energy, and mechanical energy are really the same. Then you ask, how do they differ? Simply in their phenomena--their outward manifestations. While there is much that we cannot know about any of the phenomena of nature, it is a great step in advance if we can establish a close relationship between them. It helps to free electricity from many vagaries that exist in the minds of most people regarding it; vagaries that in ignorant minds amount to superstition. While it possesses wonderful powers, they give it attributes that it does not possess. Not long ago a favorite headline of the medical electrician's advertisement was "Electricity Is Life," and it was a common thing to see street-venders dealing out this "life" in shocking quantities to the innocent multitudes--ten cents' worth in as many seconds. Science divides electricity into two kinds--static and dynamic. Static comes from a Greek word, meaning to stand, and refers to electricity as a stationary charge. Dynamic is from the Greek word meaning power, and refers to electricity in motion. When Franklin made his celebrated kite experiment, the electricity came down the string, and from the key on the end of the string he stored it in a Leyden jar. While the electricity was moving down the string it was dynamic, but as soon as it was stored in the Leyden jar it became static. Current electricity is dynamic. A closed telegraphic circuit is charged dynamically, while the prime conductor of a frictional electric machine is charged statically. The distinction is arbitrary and in a sense a misnomer. When we rub a piece of hard rubber with a catskin it is statically charged because the substances are what are called non-conductors, and the charge cannot be conducted readily away. All substances are divided into two classes, to wit, conductors or non-electrics, and non-conductors or electrics, more commonly called dielectrics. These, however, are relative terms, as no substance is either a perfect conductor or a perfect non-conductor.