The only apparatus we have at command to produce quick blows on the ether is the Ruhmkorf coil. This coil, I have said, has been in all our physical cabinets for fifty years. It contained within itself the germ of the telephone transmitter and the method of wireless telegraphy, unrecognized until the present. In its elements it consists, as we have seen, of two electrical circuits, placed near each other, entirely unconnected. A battery is connected with one of these circuits, and any change in the strength of the electrical current gives a blow to the ether or medium between the two circuits. A quick stopping of the electrical current gives the strongest impulse to the ether, which is taken up by the neighboring circuit. For the past fifty years very little advance has been made in the method of giving strong electrical impulses to the medium of space. It is accomplished simply by a mechanical breaking of the connection to the battery, either by a revolving wheel with suitable projections, or by a vibrating point. All the various forms of mechanical breaks are inefficient. They do not give quick and uniform breaks. Latterly, hopes have been excited by the discovery of a chemical break, called the Weynelt interrupter, shown in Fig. 1. The electrical current in passing through a vessel of diluted sulphuric acid from a point of platinum to a disk of lead causes bubbles of gas which form a barrier to its passage which is suddenly broken down, and this action goes on at a high rate of speed, causing a torrent of sparks in the neighboring circuit. The medium between the two circuits is thereby submitted to rapid and comparatively powerful impulses. The discovery of this and similar chemical or molecular interruptions marks an era in the history of the electrical transformer, and the hopes of further progress by means of them is far greater than in the direction of mechanical interruptions.