Progress of Invention. 77 



The means by which he effects this improvement, are very simple. 

 Hitherto the barrel of a musical clock was required to produce 

 powerful mechanical effects — it had to lift the immense hammers that 

 struck the bells, and therefore it was of necessity large and massively 

 constructed ; and to move it enormous weights, and complicated as 

 well as ponderous machinery, were indispensable. With the pneumatic 

 arrangement, the barrel merely opens valves similar to those of a 

 moderate-sized organ, and these allow the escape of air, having a 

 pressure of about two and a-half atmospheres, which gives motion to 

 the mechanism that produces the sounds. The barrel may, there- 

 fore, be as moderate in size, and the mechanism attached to it as 

 simple, as that of a self-acting organ. The air is condensed by the 

 gas-engine of Lenoir : but there seems no reason why the conden- 

 sation should not be effected by some of the enormous water-power 

 that will soon be available in all parts of Paris. 



Electko-magnetic Locomotive. — A good deal of excitement 

 exists at present in Paris with reference to an electro-magnetic 

 locomotive which is being exhibited there. It rests on four wheels : 

 those in front are small; those behind — the driving-wheels — are 

 large, and made of copper, and contain each twenty horse-shoe 

 electro magnets arranged in the direction of radii, and having their 

 poles passing through the copper tires so as to be level with the 

 outer circumference. The electric current is produced by a battery 

 which is placed at a station, and is conducted to and from the loco- 

 motive by two well-insulated wires, running between the rails. A 

 very ingenious commutator distributes it to the electro-magnets, 

 successively magnetizing and demagnetizing them. The instant 

 one of them is excited, it is attracted by the rail itself, which acts aa 

 an armature, or keeper, and the wheel is thus made to revolve, moving 

 the locomotive in one direction, or the opposite, as the case may be. 

 In the present arrangement, the electricity passes from an electro-mag- 

 net at one side of the locomotive to one at the other, that is, about 

 one quarter of the circumference in advance. To stop the engine, it 

 is of course only necessary to interrupt the current. This loco- 

 motive has one great advantage — it cannot leave the rails, or if it 

 does it will stop immediately. But the power is very trifling, and 

 much of it is lost from the indirect mutual action of the magnet and 

 rail ; nevertheless the inventors, MM. Louis Pellet and Charles 

 Rouvre, consider that it would be quite sufficient for the transmission 

 of letters and light parcels, and they even expect it ultimately to 

 supersede the ordinary locomotive. They calculate on a velocity of 

 about 124 miles an hour ; and their model does actually attain very 

 considerable speed. But supposing such a locomotive to be, even on 

 the large scale, everything that can be expected, it is still very 

 unlikely that it will compete successfully with the ordinary one. 

 Coal will afford about six times as much power as the same weight 

 of zinc, and, weight for weight, is about forty times as cheap. That 

 is, at the present price of zinc, electro-magnetic is about 180 times 

 as dear as steam-power. To get rid of this difficulty, zinc must 

 become very much cheaper, or a cheap substitute for it must be dis- 

 covered; neither of which appears sufficiently probable to afford 



