The same result was also produced, he found, by the light of a bright coal from a wood fire, or the light of red-hot iron; but not at so great a distance. Such was not the effect, however, he said, of smoke from dry resin dropped on hot iron. It was merely attracted by both shot and cork ball, forming proportionable atmospheres round them, making them look beautifully, somewhat like some of the figures in Burnet's or Whiston's _Theory of the Earth_. Franklin also noted the fact that, unlike fire-light, sunlight, when thrown on both cork and shot, did not impair the repellency between them in the least. In the same letter, guided by the belief that he had formed that electricity is not created by friction but, except when accumulated or depleted by special causes, is equally diffused through material substances generally, he also reached the conclusion that electrical discharges are due to circuits set up by substances that offer little resistance to the transit of the electrical current between bodies charged with more than the ordinary quantity of electrical energy and bodies not in that condition. In other words, electricity is always alert to restore its equilibrium when lost, and, if accumulated beyond its normal measure in one body, seeks with violent eagerness, as soon as a favorable medium of transmission is presented to it, to pass on its surplus of electrical energy to another body less amply supplied. These conceptions, too, which lie at the very foundations of modern electrical science, are illustrated by Franklin with extraordinary simplicity and clearness as follows: 1. A person standing on wax, and rubbing the tube, and another person on wax drawing the fire, they will both of them, (provided they do not stand so as to touch one another) appear to be electrised, to a person standing on the floor; that is, he will perceive a spark on approaching each of them with his knuckle. 2. But, if the persons on wax touch one another during the exciting of the tube, neither of them will appear to be electrised. 3. If they touch one another after exciting the tube, and drawing the fire as aforesaid, there will be a stronger spark between them, than was between either of them and the person on the floor. 4. After such strong spark, neither of them discover any electricity.