1198 REPORT—1885. 
number of volts which should be expended in each lamp to secure the maximum 
economic efficiency. 
He had introduced into the charging lead and into the discharging lead a 
Ferranti meter, so that he was able to record exactly the quantity of electricity 
passed through the batteries, and that passed through the lamps. This beautiful 
meter is based on Ampére’s laws, which determine the attraction and repulsion of 
currents. A small phosphor-bronze vane is immersed in a bath of mercury, 
through which the current flows radially, fixed in a magnetic field. The mercury 
rotates and carries with it the vane. The rate of rotation varies directly with the 
strength of current, and the number of rotations is recorded by a counter, which 
can be read off directly. So far, he was perfectly satisfied with its performance. 
As regards expense, excepting the first cost, he did not find much addition to 
his expenditure for illumination. His electric light was costing him about 50/. 
a year for gas, wages, oil, and lamps. It was the cheapest luxury he indulged in. 
Its great advantages were the comfort and cheerfulness it engendered; and as 
cheerfulness was the main element of health, he thought that the electric light 
would prove a serious rival to the doctor. There was no one who valued health 
and comfort who should neglect to apply the electric light to his home when it was 
brought, as it has been by the success of the secondary battery, within his means, 
It was said that he, as an expert, could make things go which would fail in ordin- 
ary hands; but he instanced several cases where coachmen, butlers, gardeners, 
and grooms had been found perfectly competent and intelligent enough to attend 
to everything. 
5. On a System of Periodic Clock Control on Telephone or Telegraph Lines. 
By Professor W. F. Barrert, F.R.S.L. 
The expense of maintaining separate lines for the sole purpose of synchronising 
the clocks in a town led the author to devise an arrangement some four years ago 
whereby telephone and telegraph lines could be utilised for clock control and also 
for burglar and fire alarm. Every subscriber to a telephone exchange is, by this 
means, enabled to have a mair clock in his house kept in true time with the standard 
clock at the Telephone Exchange. This main clock at certain times switches off 
the telephone receiver and puts into circuit the electro-magnetic arrangement 
whereby the clock is synchronised. The method adopted for this purpose is a 
modification of Ritchie’s system of hourly control, with a semaphore attached to 
indicate the true time to a fraction of a second. This main controlled clock, by a 
simple contact arrangement fitted to a disc on the arbor of the minute wheel, 
distributes time true to a minute throughout the establishment. This is accom- 
plished by an electro-magnetic minute clock of novel and very simple construction, 
which however requires a diagram to describe. The main clock also switches off 
the telephone circuit during the night, and puts in its place the fire alarum circuit 
of the house, and also the circuit passing through a safe or air tight case, which 
circuit is instantly closed whenever a burglar attempts to force the safe. In this 
way the central exchange is automatically ‘ rung up,’ and the correct house indicated 
whenever a fire breaks out or a burglar breaks in. The author stated he had had 
this system at work very satisfactorily for some time in his own laboratory. 
6. Electric Lighting at the Forth Bridge Works. 
By James N. Snootsrep, B.A., M.Inst.0.£.—See Reports, p. 879. 
7. On the Development of the Pneumatic System as applied to 
Telegraph purposes. By J. W. Wiuumor. 
It is probably not generally known by what means telegraphic messages are 
collected from the branch offices in large towns, and conveyed to the central office’ 
for transmission by wire. This service is performed by means of pneumatic tubes, 
