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From Scientific
American - Saturday, March 13, 1886 |
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The Mersey Tunnel |
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| We present herewith several illustrations of the new tunnel under the
river Mersey, between the two cities of Liverpool and Birkenhead, which occupy a somewhat
similar position in respect to each other as New York and Brooklyn. The London Graphic,
from which our views are taken, says: An improved connection between the two banks of the
Mersey estuary has been a problem for a very long time. There was a ferry across the river
as early as the eleventh century. In 1832 the first steam ferry boat, of which we give an
illustration, was launched, and since that time the traffic has so greatly increased that
the present ferry carried last year 26,000,000 of passengers and 750,000 tons of goods.
Schemes for bridges, pneumatic railways, etc., have also been mooted at various times, and
as long ago as 1864 a bill for the construction of a tunnel under the Mersey was
introduced into Parliament. |
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| Commercial panics and the opposition of vested interests, however,
prevented its passing until 1871. Even then the work was languidly supported, and it was
only in 1879, when an arrangement was made with Major Issac, that the work began to
advance. Since that time the organization has been so perfect that progress has been
unceasing, and among 3,000 men constantly employed, no death has occurred for which a
coroner's jury has blamed the company or the contractor. |
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| The initial boring experiments showed that there was an almost
uninterrupted stratum of red sandstone beneath the bed of the river, and through this the
tunnel has been made. Though no actual inundation occurred, the percolation of water,
owing to the porous nature of the sandstone, proved a source of considerable difficulty.
This was removed, however, by the gigantic pumps errected at both ends of the tunnel, of
which we give illustrations. They were kept constantly going, and were capable of
delivering 300 gallons per stroke. On the 17th January, 1884, little more than four years
after the undertaking had been regularly taken in hand, the workmen on the Birkenhead side
shook hands with those from Liverpool. So accurate had been the calculations of the
engineers, that the centers of the borings were less than an inch apart. The rapidity with
which the work had been carried out was greatly due to the use of Colonel Beaumont's
boring machine, which is driven by compressed air, and scoops out a tunnel seven feet in
diameter; large quantities of explosives, however, were also employed in the excavations.
The tunnel, which is laid with a double line of rails, is well drained and ventilated. The
ventilating tunnel, 7 feet 2 inches in diameter, is placed parallel to the main tunnel,
and at a distance of about 20 feet from it. The ventilation is accomplished by means of
fans. Two of these, each 40 feet in diameter, placed one at Liverpool, the other at
Birkenhead, ventilate the section of the tunnel which lies under the bed of the river,
while two smaller fans purify the air in the two extremities of the tunnel which lie
beneath the land. When these fans are all at work at once, they can draw out of the tunnel
600,000 cubic feet of air per minute, thereby changing the whole air of the tunnel once in
every seven minutes. In consequence of the great depth of the river, and the comparative
shortness of the line, the gradients are somewhat severe, but this drawback is obviated by
the use of exceptionally powerful locomotives, which will perform the journey between
Liverpool and Birkenhead in less than four minutes. At either end lifts capable of raising
a hundred persons at a time have been erected, so that there will be very little delay in
getting from the streets to the railway which lies so far beneath them. The tunnel is
already in full working order, and trains run freely through it. On the Cheshire side, it
is joined by the Great Western Railway system. All that remains to be done is the
connection of the tunnel railway with the Lancashire railway system. |
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