The electric railway recently set in operation between Frankfort and
Offenbach furnishes an occasion for studying the question of such roads
anew and from a practical standpoint. For elevated railways Messrs.
Siemens and Halske a long time ago chose rails as current conductors. The
electric railway from Berlin to Lichterfelde and the one at Vienna are in
reality only elevated roads established upon the surface.
Although it is possible to insulate the rails in a satisfactory manner in
the case of an elevated road, the conditions of insulation are not very
favorable where the railway is to be constructed on a level with the
surface. In this case it becomes necessary to dispense with the simple and
cheap arrangement of rails as conductors, and to set up, instead, a number
of poles to support the electric conductors. It is from these latter that
certain devices of peculiar construction take up the current. The simplest
arrangement to be adopted under these circumstances would evidently be to
stretch a wire upon which a traveler would slide--this last named piece
being connected with the locomotive by means of a flexible cord. This
general idea, moreover, has been put in practice by several constructors.
In the Messrs. Siemens Bros.' electric railway that figured at Paris in
1881 the arrangement adopted for taking up the current consisted of two
split tubes from which were suspended two small contact carriages that
communicated with the electric car through the intermedium of flexible
cables. This is the mode of construction that Messrs. Siemens and Halske
have adopted in the railway from Frankfort to Offenbach. While the Paris
road was of an entirely temporary character, that of Frankfort has been
built according to extremely well studied plans, and after much light
having been thrown upon the question of electric traction by three years
of new experiments.
Fig. 1 shows the electric car at the moment of its start from Frankfort,
Fig. 2 shows the arrangement of a turnout, and Fig. 3 gives a general plan
of the electric works.
[Illustration: FIG. 1.--THE ELECTRIC RAILWAY, FRANKFORT, GERMANY.]
The two grooved tubes are suspended from insulators fixed upon external
cast iron supports. As for the conductors, which have their resting points
upon ordinary insulators mounted at the top of the same supports, these
are cables composed of copper and steel. They serve both for leading the
current and carrying the tubes. The same arrangement was used by Messrs.
Siemens and Halske at Vienna in 1883.
The motors, which are of 240 H.P., consist of two coupled steam engines of
the Collmann system. The one shaft in common runs with a velocity of 60
revolutions per minute. Its motion is transmitted by means of ten hempen
cables, 3.5 cm. in diameter. The flywheel, which is 4 m. in diameter,
serves at the same time as a driving pulley. As the pulley mounted upon
the transmitting shaft is only one meter in diameter, it follows that the
shafting has a velocity of 240 revolutions per minute. The steam
generators are of the Ten Brink type, and are seven in number. The normal
pressure in them is four atmospheres. There are at present four
dynamo-electric machines, but sufficient room was provided for four more.
The shafts of the dynamos have a velocity of 600 revolutions per minute.
The pulleys are 60 cm. in diameter, and the width of the driving belts is
18 cm. The dynamos are mounted upon rails so as to permit the tension of
the belting to be regulated when necessity requires it. This arrangement,
which possesses great advantages, had already been adopted in many other
installations.
The electric machines are 2 meters in height. The diameter of the rings is
about 45 cm. and their length is 70 cm. The electric tension of the
dynamos measures 600 volts.
[Illustration: FIG. 2.--TURNOUT TRACK OF THE ELECTRIC RAILWAY, FRANKFORT,
GERMANY.]
The duty varies between 80 and 50 per cent., according to the arrangement
of the cars. The total length of the road is 6,655 meters. Usually, there
are four cars _en route_, and two dynamos serve to create the current.
When the cars are coupled in pairs, three dynamos are used--one of the
machines being always held in reserve. All the dynamos are grouped for
quantity.
[Illustration: FIG. 3.--GENERAL PLAN OF THE ELECTRIC WORKS.]
The company at present owns six closed and five open cars. In the former
there is room for twenty-two persons. The weight of these cars varies
between 3,500 and 4,000 kilos.--_La Lumiere Electrique._
* * * * *
By the addition of ten parts of collodion to fifteen of creasote (says the
_Revue de Therap._) a sort of jelly is obtained which is more convenient
to apply to decayed teeth than is creasote in its liquid form.
* * * * *