We find by comparison that Morse’s plan, No. 3, of using a single wire, with a single instrument, produces 60 characters per minute; while No. 1, with 13 wires, and one instrument, produces 480 characters per minute. Let, however, the 13 wires be multiplied by 60, (the number of characters which a single instrument of the plan, No. 3, can transmit,) the number of characters which 13 wires, with 13 instruments would then produce, are 780 or 300 more than the _single instrument_, with 13 _wires_. The same comparisons may be made with the other plans, and it will be found that no advantage can be gained by their adoption. All electro magnetic telegraphs require as their basis, the adoption of the _electro magnet_, where recording the intelligence is an object, and it would seem, must be applied in a manner equivalent to that mode adopted by Prof. Morse; that is, the application of the armature to a lever, and its single movement produced by closing and breaking the circuit. It is, therefore, safe to assume, that whatever improvement in one plan may be made to increase the rapidity of the movements of those parts of the telegraph which belong to the electro magnet, are equally applicable to any other plan, provided too much complication, already existing, does not counteract and defeat the improvement. Some plans, however, use an extra agent besides the electro magnet, which is employed for measuring the time of the revolution of the type wheel, and the electro magnet is only called in, occasionally, to make the impression. In such plans the rapidity of communication demands the combined action, alternately, of both magnets. This, of course, increases the complication, and must certainly be considered a departure from other more simple arrangements. Whatever will reduce the inertia of mechanical movements and bring them to act with an approximate velocity, at least of the fluid itself, will increase the rapidity of transmission. The more the instrument is encumbered with the sluggish movements of material bodies, the less rapid, inevitably, must be its operation, even where several co-operating agents are assisting, in their respective spheres, to increase the rapidity of the motion. Such is the case with the several kinds of letter printing telegraphs: very weighty bodies, comparatively speaking, are set in motion, stopped, again set in motion, and along with this irregular motion, other parts perform their functions. There must be a courtesy observed among themselves, or matters do not move on as harmoniously as could be desired. This is not always the case, especially where time is the great question at issue.