207055) for a self powered electric vehicle; the design was intended to eliminate the unbalanced oscillatory moments and "hammer blow" caused by the cranked action of a conventional mechanical steam locomotive.

[5] Heilmann wished to create a machine specifically suited for high-speed trains without the high costs of an electrified infrastructure.

The entire train was to run on bogies and use a distributed traction system provided by 12 axle-mounted electric motors in the three carriages.

[9] The locomotive had a 600 to 800 metric horsepower (440 to 590 kW)[n 1] (@ 300 to 400 rpm) two-cylinder horizontal compound steam engine with transversely mounted cylinders of 425 and 650 millimetres (16.7 and 25.6 in) diameter by 300 mm (114⁄5 in) stroke.

It was supplied with steam by a Lentz-type boiler, operating at a pressure of 12.6 standard atmospheres (185 lbf/in2),[1] with a firebox of a stayless corrugated type.

[1] The engine had a fixed cutoff with no reversing mechanism, and no speed governor excluding a centrifugal overspeed safety device.

[10] Electric speed and load control was obtained by reducing the main generator's field excitation current coming from the 10 kilowatts (13 hp) dynamo using a twelve step drum rheostat.

[11] On 9 May 1894, La Fusée Electrique made a trial run from Saint-Lazare station, Paris to Mantes-la-Jolie, hauling a train consisting eight carriages.

[5] La Fusée Electrique had been dismantled by 1897, with the bogies being used for two 0-8-0 electric locomotives which were employed on the 4 kilometres (2.5 mi) underground railway between Saint-Germain Ouest and Grande-Ceinture.

[7][14] A 1⁄10 scale model of the prototype locomotive made in 1903 is in the collection of the Conservatoire national des arts et métiers, Paris, donated by Heilmann.

[7] When one of the first diesel–electric locomotives was reported in 1905, the Automotor Journal stated it appears to be something on the Heilmann principle, that is to say the engine is employed to operate a dynamo which in turn supplies electric current to motors geared to the driving wheels.