a substance apart from the mechanism. Practically, as in the construction of the dynamo, it is never thought to arrange its parts so as to change the "condition" of the dynamo. The "collection" and "distribution" of electricity is that which is thought of, talked of, and designed. The urgent theorist can hardly suggest that the dynamo is constructed to change its own condition. The fact that electricity will operate upon a magnetic needle in a vacuum, precludes the claim that it is a condition of the needle transferred from the battery to the needle through the air. Communication with the needle must take place by means of a medium more subtile than the air. To explain the entrance of light into a vacuum, the ether is rightly supposed to be of so pure a character as to penetrate grosser matter. The same reasoning explains the operation of electricity in a vacuum and its passage from the sun to the earth. That electricity is the activity of a pure, subtile substance higher than the air and grosser matter, is consistent with all its phenomena, and is the only basis upon which explanations can be approached. It is not necessary to regard it as a substance other than ether, for the more the subject is investigated the more conclusive does it appear that electricity and ether are the same substance; or more accurately expressed, ether is a
