ndefinitely. The accumulators
used were constructed in August, 1884.

The car, as altered, had been running as an electric tram-car on the
Brussels tramways since October, 1884, till it was transferred to the
experimental tramway at Antwerp. The accumulators had been in use upon
the car during the whole of this period, and they were in good order at
the end of the experiments, that is to say, when the exhibition closed at
the end of October, 1885.

The accumulator had forty elements, divided into four series, each series
communicating, by means of wires fixed to the floor of the car, with
commutators which connected them with the dynamo used as a motor.

There were two sets of these batteries or accumulators, one of which was
being charged in the shed while the other was in use. The exchange
required ten minutes, including the time for the car to go off the
tramway into the shed and return to the tramway. This exchange took place
after every seven journeys. Therefore, the two batteries would have
sufficed for working the car over a distance of about forty-two miles
during sixteen hours.

It may be observed that the first service in the morning would be
performed by means of the accumulators charged during the afternoon and
evening of the previous day.

Each element of a battery was composed of nineteen plates, of which nine
were positive, four millimeters thick, and ten negative, three
millimeters thick. Each positive plate weighed 1.44 lb., of which about
twenty-five per cent. consisted of active material. Each negative plate
weighed nearly 1 lb., of which one-third consisted of active matter. The
weight of the metallic part of the battery amounted, therefore, to 1,846
lb.; and the whole battery, including the case and the liquid, amounted
to 2,464 lb., which contained 499 lb. of active matter, or about 20.25
per cent. The four cases in which the battery was contained were so
arranged as to divide the weight equally between the wheels.

Two commutators inclosed in a box were placed on the platforms at the two
ends of the carriage, so as to be available for moving in either
direction.

The accumulators were divided into four series of ten double elements,
which, by means of the commutators, could be united under four
combinations, viz.:

1st. 4 series in quantity--1 in tension.
2d. 2 " " " 2 "
3d. 3 "
4th. 4 "

Finally, a fifth