A few months ago there was exhibited, in the society's reading room, a working model of an application to railway working of what the inventor calls "division of the mass." In causing a body, moving at a high velocity, to communicate motion to another at rest, or moving at a lower velocity, he splits one of them up into parts all the more numerous, and therefore tenuous, as the difference in velocity is greater; and this is accomplished by causing one of the parts to take the form of a brush composed of metal fibers. In applying this principle to the transmission of motion for driving machinery, a disk, fitted with segmental brushes, is slid laterally along the shaft, so that the fibers come into contact with radial projections on a second disk; and, although the contact is made instantaneously, the action is exerted gradually, owing to the flexibility of the fibers. That is to say, the full power is communicated without any shock. A similar arrangement, but with one of the disks fixed, serves as a brake for arresting motion, and this again without shock, but with gradually increasing action. Where space is very much circumscribed, the clutch and the brake may be combined, by fitting a disk with brushes on one side, and projections on the other, so that it may be brought by a lever against a second disk, for transmitting motion, and against a third, fixed, for stopping it. Safety appliances for arresting the descent of mine cages, in the event of the rope breaking, have hitherto depended upon the entrance of claws into the guides, or the clipping of the latter, or the wedging of the cage between the guides. In this application of the system, the guides of the shaft are fitted with corrugated iron plates, and the sides of the cage with steel brushes. In the normal state of working, the brushes are kept clear of the guides, but, should the rope break, a small brush, fitted on a sector, constantly rubbing against the corrugations of the guides, aided by a spring or counterweight, brings the main brushes into contact with the guides by a link arrangement, like that of the parallel ruler, thus arresting the cage, and holding it suspended until the brushes are gradually relaxed, for "braking" the cage slowly down to the next landing. Many attempts have been made to cause a locomotive, running at full speed, to exert such a mechanical action as would set a signal to danger, so as to protect the train from another following in the rear. By fitting the engine with a steel brush, attached to the axle boxes, so as to preserve a uniform height with respect to the rails, a stationary lever may be gradually moved, so that the signal is set at "danger" without shock. Moreover, by means of another brush, in the event of the engine being turned upon the wrong line, a lever may be made to shut off the steam, apply the brakes, blow the whistle, or move an index on a dial, recording a neglect of duty, or may exert these four actions simultaneously.