At a recent meeting of the Institution of Civil Engineers, a paper on the
above subject was read by Mr. Edward Bayzand Ellington, M. Inst. C. E. The
author observed that water power was no new force, but that, as formerly
understood, it was limited in its application to systems of mechanism
suitable for the low pressures found in nature. The effects obtained by
the use of high pressure were so different in degree from all previous
experience, that a new name was needed, and had been found in the term
"hydraulic power." Bramah's genius produced the hydraulic press, and he
clearly foresaw the future development and great capabilities of his
system; but it was reserved for Lord Armstrong to work out and superintend
the intricate details that had to be developed before the system could be
made fully serviceable. The public supply of hydraulic power in London
constituted the latest development of this system. The hydraulic power was
supplied through mains charged by pumping at a pressure of 700 lb. per
square inch. The first and largest pumping station had been erected on a
site known as Falcon Wharf, about 200 yards east of Blackfriars Bridge.
The engine house at present contained four sets of pumping engines, each
set being capable of exerting 200 I. H. P.
The engines were vertical compound, of a type comprising the advantages of
a three-throw pump with direct connection between the pump plungers and
the steam pistons. Each set of engines would deliver 240 gallons of water
per minute into the accumulators at 750 lb. pressure per square in. at a
piston speed of 200 ft. per minute. This was the normal speed of working;
but, when required, they could be worked at 250 ft. per minute, the
maximum delivery being 300 gallons per minute. The condensing water was
obtained from storage tanks over the engine house, and was returned by
circulating pumps to one or other of those tanks. The water delivered into
the mains was maintained all the year round at temperatures of between 60 deg.
and 85 deg. The boilers were of the double flued Lancashire type, and were
made of steel. All were fitted with Vicars' mechanical stokers. At the
back of the boilers was a Green's economizer, consisting of ninety-six
tubes. The economizer and the stoker gear and worm were driven by a
Brotherhood three cylinder hydraulic engine. The reservoir of power
consisted of accumulators. The accumulators at the pumping station were
two in number, each having a ram 20 in. in diameter and 23 ft. stroke.
The weight cases were of wrought iron, and were filled with iron slag. The
total weight of the case and load on each ram was approximately 106 tons,
corresponding to a pressure of 750 lb. per square in. The storage tanks
formed the roofs for the engine and boiler houses. The water for the power
supply was obtained from the river Thames, and was pumped into the tank
over the engines. The water passed through the filtering apparatus by
gravity into the filtered water tank over the boiler house, which was 7
ft. below the level of the unfiltered water tank. The filters consisted of
cast iron cylinders, and each contained a movable perforated piston and a
perforated diaphragm, between which was introduced a quantity of broken
sponge; the sponge was compressed by means of hydraulic pressure from the
mains. The delivery of power water from the Falcon Wharf pumping station
was through four 6 in. mains. The most distant point of the mains from the
accumulators was at the west end of Victoria Street, and was 5,320 yards,
or just over three miles. To provide for all frictional loss in the pipes
and valves, the accumulators had been loaded to 750 lb., the stated
pressure supplied being 700 lb. per square in. The total length of the
mains at present laid was nearly twenty-seven miles. The mains were laid
in circuit, and there were stop valves at about every 400 yards, so that
any such section of main could be isolated.
The method employed for detecting leakage was based upon an automatic
record of the number of gallons delivered into the mains, and in cases of
abnormal increase during the night, if found to arise during the early
hours of the morning, the mains were tested. The power water used was
invariably registered through meters on the exhaust pipes from the
machines, and from the meters passed to the drains. There was a sliding
scale of charges from 8s. to 2s. per 1,000 gallons at 700 lb. pressure per
square inch, designed to meet, as nearly as possible, the variable
conditions and requirements of consumers. The more continuous the use, the
lower the charges. The scale was intended chiefly for intermittently
acting machinery, and experience had fully proved that these rates were
sufficiently low to effect a large saving to the consumer in almost all
cases, whether for a large or a small plant. The author believed any idea
of supplying power from a central source at rates much below these to be
chimerical. The practical efficiency of the hydraulic system might be
fixed at from 50 to 60 per cent. of the power developed at the central
station. No other method of transmission would, he thought, show a better
result; and the general convenience and simplicity of the hydraulic system
were such that its use would hardly be affected, even if there were no
direct economy in the cost of working.
In addition to the general supply of hydraulic power, in the City and
adjoining districts, to the six hundred and fifty machines at present
worked, a new departure had been taken by the application of hydraulic
power to an estate at Kensington Court--the name given to an area of about
seven acres opposite Kensington Gardens. Seventy houses and dwellings were
to be built on this estate, of which thirty had been already erected. Each
house was fitted with a hydraulic lift, taking the place of a back
staircase, and the power supply was provided on the estate expressly for
working these lifts. The driven machinery was of as great importance to an
economical and satisfactory result as the distributing plant, but this
obvious fact was not always understood. General regulations had been
prepared by the author, defining the conditions to be observed by
manufacturers in fitting up machinery for connection to the power mains.
They were intended to secure safety, and an efficient registration of the
quantity of power used; but they left the question of the economy and of
the efficiency of the machines to be settled between the consumers and the
makers. In London more lifts were working from the mains and more power
was used by them than by any other description of machinery. The number of
all classes at present at work was over four hundred. The principal types
in use were fully described. In some cases there had been, by adopting the
public supply, a saving in the cost of working of about 30 per cent., as
compared with the steam pumping plant previously in use.
Lifts were now becoming so general, and the number of persons who used
them was so great, that the author considered it necessary to urge the
importance of securing the greatest possible safety in their construction,
by the general adoption of the simple ram. Suspended lifts depended on the
sound condition of the ropes or chains from which the cages hung. As they
became worn and unreliable after a short period, it was usual to add
safety appliances to stop the fall of the cage in case of breakage of the
suspending ropes; but they could not be expected to act under all
circumstances. As an indication of the important part which lifts occupied
in a modern hotel, it might be mentioned that at the Hotel Metropole there
were, including the two passenger lifts and that for the passengers'
luggage, no less than seventeen hydraulic lifts in use day and night,
while the work done represented about 2,000 tons lifted 40 ft. in this
time. The next largest use of the power was for working hydraulic cranes
and hoists of various kinds along the river side, and in the city
warehouses. It often happened that the pressure in the power mains was not
sufficient for pressing purposes.
The apparatus known as an intensifier was then used, by which any pressure
required could be obtained. Hydraulic power was also used at Westminster
Chambers, and elsewhere, for the purpose of pumping water from the chalk
for domestic use. The pump was set going in the evening and continued
working till the tanks were full, or until it was stopped in the morning.
For work of this kind, done exclusively at night, a discount was allowed
from the usual rates. Mr. Greathead's injector hydrant, made at the
Elswick works, had been in use to a limited extent in London in connection
with the power mains.
A small jet of high pressure water, injected into a larger jet from the
water works mains, intensified the pressure of the latter in the delivery
hose, and also increased the quantity. By this means a jet of great power
could be obtained at the top of the highest building without the
intervention of fire engines. This apparatus enabled the hydraulic power
supply to act as a continuous fire engine wherever the mains were laid,
and was capable of rendering the greatest assistance in the extinction of
fire; but there was an apathy on the subject of its use difficult to
understand. In Hull the corporation had put down a number of these
hydrants in High Street, where the hydraulic power mains were laid, and
they had been used with great success at a fire in that street. The number
of machines under contract to be supplied with power was sufficient, with
a suitable reserve, to absorb the full capacity of the station at Falcon
Wharf, and another station of about equal capacity was now in course of
erection at Millbank Street, Westminster. The works had been carried out
jointly by the author and Mr. Corbet Woodall, M. Inst. C. E.; Mr. G.
Cochrane had been resident engineer and superintendent. The pumping
engines, accumulators, valves, etc., and a considerable portion of the
consumers' machinery, had been constructed at the Hydraulic Engineering
Works, Chester. Sir James Allport, Assoc. Inst. C. E., who was the first
to adopt hydraulic power for railway work, had been associated with the
enterprise from the commencement of its operations in 1882. His wide
influence and extended experience had greatly assisted the commercial
development of the undertaking.