rking speed was at least eight miles per hour.
The supply of power is also a matter not referred to particularly, as
in many cases a lighting plant is used by the contractors, which could
also be employed to provide the necessary energy for the electric
railway. The good work done by small electric locomotives in the
excavation work for the Waterloo and City Railway[1] will convince our
large contractors of the valuable service which electricity can render
both above and below ground.--The Electrical Engineer.

[Footnote 1: Electrical Engineer, vol. xvi., p. 499.]

* * * * *

A connection between Servian and Roumanian railways is to be
established by bridging the Danube. It is reported proposals have
already been made to the governments interested, by the Union Bridge
Company, also by British and French constructors.--Uhland's
Wochenschrift.

* * * * *

LIQUID RHEOSTATS.

BY H. S. WEBB.[1]

[Footnote 1: In American Electrician.]

The object in view when the following tests were commenced was to
obtain some data from which the dimensions of a liquid rheostat for
the dissipation as heat of a given amount of energy could be
calculated, or at least estimated, when the maximum current and E.M.F.
are known. These tests were rather hastily made and are far from being
as complete as I should like to have them, and are published only to
answer some inquiries for information on the subject.

In the first test, an ordinary Daniell jar (61/4 inches in diameter by 8
inches deep) with horizontal sheet iron electrodes was filled with tap
water. It would not carry 4 amperes for over fifteen or twenty
minutes, although the jar was full of water and the plates only 3/4 inch
apart. After that length of time it became too hot, causing great
variation in the current on account of the large amount of gas
liberated, much of which adhered to the under surface of the upper
electrode. The difference of potential between the plates was 200
volts.

A run was made with 1 ampere and then with 2 amperes for one hour. In
the latter case the voltage between the electrodes was about 71 volts
and the temperature rose to about 167 deg. F.

From these tests it would be safe to allow a vessel with a cross
section of 30.7 square inches to carry from 2 to 21/2 amperes when tap
water and horizontal electrodes are used.

In test No. 2 the same jar and electrodes were used