The Sun.
London, England, 1864-09-08 00:00:00

The Spithead Forts.

There s probably at the present time no other
portion of the national defences which has so large
a hold on t ke public mind as the proposed marine
forts at Spi thead. This is due to several causes,
foremost am ong -which may be noticed the conflict.
ing evidence relative to their necessity given before
the National i)efence Commission by officers of the
highest rank In both services, and other competent
witnesses; the subsequent discussions in the press
and Parliamer it; the temporary suspension of the
works and the !sir subsequent resumption, and, per-
haps more th en all the foregoing reasons put to•
gether the ab sorbing interest imparted to the sub-
ject by the ni real operations before Charleston and
Mobile. Ttee Defence Commissioners originally
proposed tha t Spithead should be protected by a
combined system of forts and floating batteries,
and they recommended the construction of five ad-
vanced forts on the shoals—on the Horse Sand ;
Numan, or No Man's Land Shoal ; on the Stnr.
bridge Shoal, off Ryde, on the Spit Point ; and on
a point intervening between the Horse Sand and
the south-east end of Portsea Island. Sir Charles
Fox with a staff had been employed by the War-
office department in baring the different shoals,
and a report of the result was drawn up by Sir
Charles for the guidance and instruction of the
War-office on the subject. Mr Hawkshaw, C.Ee
prepared the plans for the foundations, and three
eef those plans—the Horse Sand, the Noman, and
the Stubridge—were ordered to be proceeded with,
the one on the Spit and the one intervening be-
orse Sand and the Portsea Island
tween the 11
having
been thrown out of the scheme. The euu-
tract for the construction of these foundations was
signed by Mr Leather, a gentleman who has
gained high reputation by his work at Portland,
in June, 1861; bat owing to the temporary sue.
pension of the works, in deference to the ex-
pressed feelings of a large party in the House of
Commons, it is only on the Horse Sand that any
great progress has been made, and in the meantime
the Sturbridge Shoal has been abandoned, owing to
the enormous expense which must have been in-
curred in constructing the foundation for the Fort
there from the nature of the shoal. On the 11th of
June, 1864, a special committee was appointed by
the Secretary of State for War "to consider the
alterations requisite in the plan for the defence of
Spithead in consequence of the abandonment of the
work on the Sturbridge." This committee was com-
posed of Rear-Admiral A. Milne, chairman ; Capt.
R. S. Hewlett, R.N. ; Colonels J. W. Gordon, R.E,,
C. V. Cockburn, R.A., and H. D. Harness, R.E. ;
Capt. J. D. Bythesea, R.N. ; Mr. James Ferguson,
with Lieut.-Colonel W. F. D. Jervois, R.E., Deputy
Director of Fortifications, as secretary. This cam.
mittee, after visiting Spithead and its approaches,
recommended that a fort should be constructed on
the Spit Bank, about 600 yards to the south-west
of the point on which it was proposed by the De-
fence Commissioners to erect a fort. They also
recommended that, as an enemy might pass by the
outer forts and keep so far to the southward as to
be out of the effective range of the works on the
slcrthern side of the anchorage, a small fort should
also be constructed on the Ryde Sand, about 1,200
ylArds to the southward of the Sturbridge Shoal. In
acwordance with these recommendations of the com-
mittee the War-office authorities are now employed
at the two points indicated in boring the shoals to
ascertain their nature. The borings have already
beam carried to a considerable depth, but with no
promising results. On the Ryde Sand nothing has
yet been met with bat a thick layer of sand deposited
on mud, and the situation is as unpromising there
a s was the Sturbridge Shoal. The position selected,
600 yards south-west of the Spit point, is equally
unpromising. It is evidently off the shoal proper,
s nothing has yet been met with in the borings
bat sand and earthy deposit left on the edge
of the shoal by the action of the tides. The
efforts of the commission appear to have been
restricted to finding a substitute for the Sturbridge
site, north of the Noman, and Horse sites, other-
wise it is incomprehensible that the Warner posi.
t, ion should have been left without mention in the
CG menittee's report. If the chart published in the
report of the National Defence Commission is re.
ferried to it will be seen that the works now in pro-
gress on the Horse and Noman shoals form two
points fen equilateral triangle, the apex of which
is the Warner Rock, a trifle inshore of the Warner
lightship. The similitude in the two positions of
Spithead and Charleston in their outer defences is
very striking., but it is all in favour of our own port.
Forts M oultrie and Sumter are 1,900 yards apart.
The fort s on the Horse and Noman Sands will be
2,000 ye rds apart, but they will be 1,000 yards fur-
ther die taut from Portsmouth than Sumter and
Moultrie, are from Charleston. The probable failure
of findir,g any suitable strata on the Spit or Ryde
Sand on which to erect the two forts recommended
by the commission may also induce the authorities
to again, take into consideration the propriety of
erecting a tort on the Warner Rock, and thus trebly
locking' the front-door entrance into Spithead from
the sea. The three forts would then form an equi-
lateral triangle, both sides of 2,000 yards, and, if
kept armed with the heaviest description of ord-
nance as our knowledge in gunnery progressed, it
would be absolutely impossible for any ironclad that
could ever be constructed to pass through that tri-
angle of firs and float. This plan has met with
much favour. It was first brought into notice by
Captain H. W. Tyler, R.E., then stationed in the
Isle of Wight, in charge of the fortifications in that
district in the early part of 1863 ; and as time pro.
gresses and our knowledge of the relative value of
forts and armoured ships likewise advances, the real
merits of Captain Tyler's plan becomes more and
more apparent.

To return, however, more directly to the works
now in hand, the Horse and Noman foundations, it
is necessary to first observe that, after a certain
progress had been made in the collection of plant,
the erection of staging over the foundation sites,
and other preliminary measures, the Government
appeared for some time to falter in their determina-
tion to erect the forts. The contractor never eels
tered. He felt that a reaction must come; he knew
the forts were to a certain extent as certain to be
constructed as day succeeds to night, and he know
also, as Lord Palmerston told the House of Come
mons, that to give np the scheme at that paint
would entail nearly as great an expense as its corn
plotion. Under these circumstances Mr. Leather
steadily went on collecting his plant and material
on shore, and the result may now be seen at the
Spitbead Forts' works on Stokes Bay shore, nearly
opposite Ryde, Isle of Wight, where the first pre-
parations for the construction of the forts' founda-
tions are made, and where also a desert strip of
shingle and stunted gorse has been transformed
into a busy hive of human industry. The position
has been well selected. It adjoins the Stokes Bay
railway terminus, is within half an hour's steaming
of the Horse and Noman, and its beach offers a
safe means of embarking and disembarking in all
weathers. On the ground is a cement mill, cement
stores, blacksmiths' shops, &c., with lines of rail-
way traversing it in all directions, a line of rail
forming a junction with the Stokes Bay railway
and overhead railways worked by
company's lie©,
steam cranes of great power for transporting the
blocks of stone. About 15,000 tons of concrete
blocks are at present laying on the ground squared
and bevilled off in readiness to drop into their places
in the foundation courses of the forts, and about
7,oooltone of Penbryn granite, Portland and Run-
corn stones for the same purpose. These blocks
range, according to their position, from three to
seven tons each. Portland and Pen bryn stones are
conveyed to Stokes Bay, or Leather-town, 118 it may
in all propriety be called, by sea, but the Runcorn
atones are delivered direct by rail from Birkenhead.
In one part of the works a portion of the ground is
cemented Over and laid out as a I) rawing Board,'
on which every stone is laid in its own position as
it will finally occupy when placed under water,
and is there numbered and marked out with its
fellows in coloured lines, and by these numbers and
coloured linen the diver 11 4.: the stone when low-
ered to him from above. In the centre of the station
on the branch line is built a stout pier, having a
double line of railway connected with the railways
on the grounds, and on this pier railway a pewer-
ful steam crane affords the necessary means of re-

ceiving the roughlyeequared blocks of stone and
granite from Portland and Penbryn, and discharg-
ing all the finished blocks into the liglrer:-, which
convey them, towed by steamtugs, to toe works on
the Horse and Noman. The concrete blocks are
made from the shingle and sand of Srckes Bay and
the best Portland cement. The total value of Mr.
Leather's plant, in connection with the Spithead
Fort Works, is estimated at over £40,000.
The site of one of the forts once definitely fixed
upon, the War Department first enter on posses.
sion, drive some dozen piles in a central position,
cover those with planking, erect a temporary light-
house, and begin to sink their cylinders, just after
the plan pursued in the construction of the Char.
ing-cross railway bridge. By means of these
cylinders an exact knowledge of the strata of the
earth below is obtained, and they also afford the
means of obtaining water at a moderate depth from
the surface if they reach a water-bearing strata. On
the Horse Sand the cylinder (in sections of Gft, dia.
meter) has been sunk to a depth of 90ft, but no
water found, and it is now intended to make water-
tight by artificial means the bottom of the lowest
cylinder section, and then by boring it is calculated
water will be obtained on reaching the London clay,
about 500 ft from the surface. The same course will
be followed at the Noman. The London clay crops
out, about 15ft below the surface, in the new No. 11
dock foundations bed now in course of construction
in Portsmouth dockyard. At the Horse and Noman
forts water is expected to be found in the stratum of
sand which intersects the London and plaster clay
beds. The foundation ground on the Noman and
Horse banks is everything that could have been
lA..d v."- iic .),„ Shoal th. sun,
face consists of 4ft 6in of fine gravel and sand, which
rest upon 2ft of natural concrete. Next comes a
stratum of 18ft of sand, containing shingle and
pieces of tree bark and branches. Eight feet of
clayey sand succeeds to the sand and shingle, and
contains remains of various marine substances. Next
comes a 5-feet stratum of sand shingle, followed by
15ft of a blue silty clay; a stratum of sand, shells,
and shingle; a thin stratum of stone; and, lastly, a
conglomerate of flints, sand, and shingle, All this
is evidently a modern deposit. The cylinder on the,
Horse Shoal has been sunk in the usual manner by
internal excavation. The cylinder on the Noman
Shoal has been sunk by a pneumatic process worked
up at last to an air pressure of 371 b to the inch until
in fact the vulcanised pipes could withstand the
pressure no longer, but gave way with a report like
a cannon shot. This was beyond endurance by the
human frame, and several men were incapacitated for
a time for further bodily exertion. It is a curious fact
that Sir Charles Fox, in his report to the War-office,
should have been entirely deceived in his conclu-
sions as to the under stratum of the Noman Shoal.
This he described as being composed of the Isle of
Wight limestone rock, which crops up on the shore
at the adjacent point of sea view, Nett:estone, as it is
marked on the charts. Contrary to this theory of Sir
Charles it is composed of sand an d shingle intermixed
with ,large pieces of limestone, evidently washed
down from the is:and strata, and in coming across
these detached pieces of limestone Sir Charles, no
doubt, fell into toe error of his theory. In these
cylinder excavations on the Noman the lower jaw
of a graminivorous animal was found 55ft below the
surface of the shoal. This was forwarded to Pro-
fessor Owen, who gave it as his opinion that it was
the jawbone of an ox or extinct species of deer.
How long had this jawbone been thus buried ?
We now come to the time when, the War Depart-
ment having erected its central staging, sunk its
cylinder, and examined the lower strata, the con-
tractor for the foundation of the forts comes upon
the scene and commences his operations for laying
the foundations of the forts comes upon the scene
and commences his operations for laying the foun-
dations of the forts. This he does by taking the
War Office staging as his base of operations, and
throwing out thence radial arms of timber, embrac-
ing the area required for the foundation, which are
supported on screw piles, and the superstructure is
formed of circular timber roadways, on which is
laid a line of railway, on which work powerful tra-
velling steam cranes, which lift the blocks of stone
from the lighters and drop them into their position,
in the water, where the divers below receive and
fix them according to their numbers and coloured
lines. This circular staging is divided into 25 sec-
Lions, and this arrangement, together with the
numbers and coloured lines on the stones, prevents
any possibility of a mistake in the final fixing of
the stones by the divers under water. Fifty men
are now employed on the Horse fort foundations, 12
of whom are divers. The foundations of this fort
are expected to be completed by the end of the pre.
sent year. The Noman and Horse foundations are
precisely similar in their structure, but differ-
ing in their height, the Noman requiring
from its greater depth of water nearly double
the depth of stonework from the shoal to that
necessary on; the Horse Shoal. Both founda-
tions are formed of rings of stonework, laid on the
levelled bed of the shoals, of 53ft. Gin, of base, and
42ft. Gin, at the upper course. The outer diameter
of the ring is 231 ft. at low water mark, and 213 ft.
at the upper course. There is thus a considerable
area in the centre of this ring of stonework, which
can be filled up around the cylinder subsequently
by the Royal Engineering Department, into whose
charge ,the foundations fall after their completion
by the contractor, according to their own ideas.
Five courses of stonework form this ring at the
Horse, and each succeeding course lessening its dia.
meter from the base by 4ft Gin, gives the difference
in external diameter between the base and upper
course. The inner and outer diameters of the lower
courses are laid with the soft red Runcorn stone.
The same diameters of the upper tiers are laid with
Penhryn granite to bear the weight of the fort to be
constructed above. The heart of the work is filled
in with concrete blocks. The Noman foundations
are precisely similar in their five upper courses, but
they will have an additional four courses below of
Portland roach stone, having a vertical facing from
the shoal. The Noman Shoal is covered with 20ft.
of water at high water spring tides, and the Horse
Shoal with 15ft. Round the base of each founda-
tion on the shoals will be deposited sufficient rubble
to protect the stonework from any damage by the
tidal rush of the waters, or the break of the waves
in rough weather.

In executing a work in an exposed position in
tidal waters, the first danger (and sometimes it is
a continuous danger from first to last) the contrac.
tor has;to meet with is the action of the breaking
waves upon his piling in rough weather. This has
been provided for in the Spithead works by
Mr. Leather in the construction of a sys-
tem of piling that shall present the least re-
sistance to the sea, and at the same time
that possesses abundant strength to support
its superstructure. The best known illustra-
tions of the two systems of piling for submarine
works exist at Dover and Holyhead. At the former
places the piling and staging is a mere reed-like
structure that at first sight appears far too frail to
maintain its position in even a moderato breeze,
against the wash of the sea ; yet it in reality pos-
sesses by its judicious arrangement an enormous
amount of sustaining strength, enabling it to defy
the attacks of the strongest gale. At Holyhead, on
the contrary, the staging that has been erected
there for the completion of the pierbead 3has heeta
swept away time after time, owing to its too great
bulk and consequent resisistance to the sea. Iu the
great gale which destroyed the Royal Charter the
piles and staging swept from off the end of the
Holyhead pier works, drifted alongside the Great
Eastern, then anchored in the bay, and, by fouling
her paddles and screw, placed her in jeopardy for
some considerable time.

With regard to the Spithead forts themselves
nothing definite appears as yet to have been arrived
At. In the fiat place it sv,7s intended to construct the
forts entirely of iron. It W 33 next proposed to con-
strwt them of granite faced with iron, in the same
manner Bs,the Uronstadt forts are now being com-
pleted. It is said, however, that the authorities,
frightened at the cost of iron forts, and not knowing
where to turn for s good intermediate 8U bLztance bc-
twcen the iron face and granite backing, intend to
construct the forts simply of granite, and leave their
coating outside for further considcrati7m. if these
forts are to fight iron.3llips, and that is what most
people believe must one day
be their duty, they

must be constructed either of iron or clothed with
iron. If the latter course is adopted, there can be no
difficulty about the matter, for any thickness of
armour-plating can be fixed on the exterior of the
granite face by the aid of double T ended angle fram-
ing, and the interstices could be filled with sand to
prevent any damage to the granite by the blow of an
enemy's shot. This sand backing would also lessen
the vibration of the armour plate on being struck,
and would afford space for the removal of any
damaged armour plate, and the fixing of a sound
one in its place without disturbing the granite
frame of the fort. On the Noman the contractor's
circular staging has just been commenced. It will
be fully two years before the foundations of the fort
there can be completed.

There is one fort now just taken in hand by Mr
Leather, at no great distance from the Horse and
Noman, which, although it is included in the " Isle
of Wight Defences," is really a marine fort, and
must be looked upon, as one in the group of the Spits
head defences. This will be erected on the sandy
spit which runs out towards St. Helen's Roads, on
the south side of the entrance to the shallow har-
bour of Brading, the very spot where this fort will
stand being the silted-up sand and shingle which
covered up by tidal and wind action the works com-
menced by Sir Walter Raleigh for the protection
and extension of Brading Harbour. The fort will
be of an oval form, of 120 ft. in length, and about
190 ft. in breadth, and built of granite. A ring of
caissons will be sunk in the sand, after the manner
of those used in the formation of the Thames Em-
bankment, and within this ring will be formed the
foundation for the tort. The caissons will afterwards
be filled in with concrete and become a permanent
outer protective circle for the werl2,