The Sun.
London, England, 1860-12-26 00:00:00

P Olat ilifOU.7ll AND ITS DEFENCES.

S. ince the notice in The uas of the 10th of January
last, of 'the new lines and works for the defence of
Pcirtstd(outh by land and sea, considerable progress
has been made in their construction, and many
al#,eratiens and 'additions have been made to the
plans as originally laid down, the most important
,of all being the proposed fortification of Portsdown-
hill, in front of the Hilsea lines, and apparently
comme.ndi ng the entrance by land to Portsea Island.
This yosi.tion (Portsdown) is seven miles in extent;
and, from the important bearings towards each
other of Portsdown and Hilsea, we propose to leave
their consideration until the circuit of the remaining
'line of defences has been gone through, commenc-
ing at its south-eastern point, Fort Cumberland, and
proceeding by Southsea Castle, Forts Monckton and
Gomer, the chain of forts hence to Frater-lake,
the proposed detached forts in advance to the
-westward, and thence to Portsdown and Hilsea.
The island of Portsea is of an irregular oval figure,
about 16 miles in circumference, separated from the
mainland 'by a creek between Hilsea and Cosham,
which unites the harbours of Portsmouth and Lang-
ston ; is bounded on the east side by Langston
Har'oour and Hayling Island, on the west by Ports-
mouth Harbour, Gosport, Fareham, Ac., and on the
feauth by Spithead and St. Helen's. The new lines
of defence, it will be seen, extend considerably into
the peninsula on the western side of Portsmouth
Harbour, taking their course along the sea beach to
the westward, thence stretching across the country
at right angles until the upper portion of Ports-
mouth Harbour shores are reached, and the pro-
posed intrenchments on Portsdown completing the
circuit thence to Hilsea. Returning to our starting
point, Fort Cumberland, this work stands at the
mouth of Langston Harbour, on the end of a line
of sea-beach 4,300 yards in length, the correspond-
ing end of which is held by Southsea Castle with
its auxiliary earthworks, both strongly enclosed
works, the first-named mounting about 50 guns of
the heaviest calibre ; and Southsea, with its auxi-
liary batteries, mounting about 53. Southsea Castle,
as the outpost guarding the entrance of Portsmouth
harbour channel, is the more important work of the
two, and its earthworks are consequently to be
considerably increased and strengthened. The
line of beach between these two forts is to be
further defended by two intermediate forts—East-
ney and Lumps, the latter of which is nearly
completed, and, as both will be of precisely
similar construction, a description of one will
suffice. Lumps is constructed to carry nine 8 and
10-inch guns, and is provided with revetements
27 feet high, with a ditch in front, flanked by
caponussres for musketry. In the interior of the
work accommodation is made under the terresplein
for 100 men. The rear of the work is closed by
brickwork, with a building for officers' quarters,
entrance gateway, ix. The sea face of the work is
covered in the usual manner by an earthen glacis.
The fort in front presents a sufficiently formidable
appearance, especially taking into consideration
that the whole line of beach from Southsea Castle
to the eastward is only accessible to gunboats of
light draught at high water, or boat flotillas. The
rear of the fort is, however, very weak. It is sup-
posed that two or three pieces of light calibre may
be mounted on the roof of the officers' quarters to
assist in defending its rear face, but it is also evi-
dent that a couple of field-pieces, landed from an
enemy's boats and brought to act on the same spot,
would render the fort untenable. Straith and
other authorities lay it down as a rule that all
detached works at a distance from the main fortress
should be surrounded by a ditch, and present the
same obstacles in the rear as in front.

Passing by the entrance to Portsmouth harbour,
defended, exclusive of Southsea Castle, by upwards
of 100 guns of the heaviest calibre, the next point
reached is Fort Monckton, flanking, with its 48 6,
8, and 10-inch guns, the line of ditch and rampart
erecting for the defence of this portion of the lines
along Stokes Bay, and extending to beyond
Gomer Fort. The greater part of the earthworks
here are finished, or nearly so, and the brickwork
and masonry for the batteries flanking the line of
ditch are also drawing towards completion. The
main defences on this line, consisting of detached
forts and batteries on the rising ground in the
immediate rear of the lines, have, however, not yet
been begun, but the whole, when complete, will
form an almost invulerable line of defence. This
had need to be the case, for an enemy effecting a
landing in the bay and forcing any portion of this
line would turn the whole position, and Portsmouth,
its dockyard, arsenal, and shipping, would lie at his
mercy. Great care has been taken in designing the
plans for this portion of the defences, owing to their
great importance, and where the water deepens on
the beach the line of rampart and ditch, the outer
defence, recedes, while at the point where it shoals
the line more boldly advances, until it approaches
to within a very short distance of high-water mark.
Seawards this is the most tempting point for an
enemy to attack, should his object be the capture
or destruction of the dockyard and shipping. He
has but to force the line at this point, and the
monster line of fortifications at Hilsea and the chain
of forts from Stokes Bay to Frater Lake would be
useless, and must fall into the enemy's hands, and
that without the necessity of striking another blow.
Stokes Bay presents every facility for landing troops;
while at high-water the Gloire could approach
within less than 250 yards out of the outer ditch
and rampart. This line of outer defences, com-
mencing at Fort Monckton in the midst of swamp
and morass, ends with a square casemated work in a
similar description of ground slightly in advance of
Fort Gomer, an enclosed work in an almost inac-
cessible position, and mounting 32 6,8, and 10 inch
guns, and two 13-inch mortars. In advance of both,
on the shingle of the beach, are the auxiliary
Browndown batteries, mounting 21 8-inch guns.
The ground in the rear of the line just described
rises to an average of 18 feet, and on this will be
constructed the works which will form the really
defensive portion, connecting Monckton with
Gomer, none of which have, however, yet been
commenced. From Gomer Fort to Frater Lake are
the forts of Grange, Rowner, Brockhurst, and El-
son, the latter of which only is finished, armed, and
manned. The remainder are nearly completed but
are to be connected by a line of ditch and rampart,
their rear faCes being weak in a similar manner to
Lumps Fort. In advance of this line of connected
forts, and commencing at Hill-head, a point of land
to the westward of Stokes Bay and terminating
near Fareharn, will be erected a line of detached
forts, considerably in advance of the main line of
d, fence, and each complete as a work of itself. The
northern fort Neill prevent an enemy who may have
effected a landing in any part of the Solent from
seizing on the approaches to Portsdown-hill. From
Fareham to Chichester runs the public main road, ,
is most likely an enemy would ad-
along which it
vance, either from the (2estward or westward. In
making this advance his first object would be to
take possession of the heights of Portsdown, but to
do this from the westward will be almost impossible
owing to the position of the detached advanced
forts, and especially of the one at Itsonae. The
approach to the hill on the eastern side has not re-
eeived equal attention. A strong detached work
near Bedhampton would effectually protect the hilt
from any enemy advancing direct upon it by the
main road from Chichester. This fact deserves seri-
ous attention. Selsea Bill, with a wind at south-
west in the Channel, affords, in conjunction with
its reefs of rocks running off miles into the Chaoticif
I
a safe and easy spot for the debarkation of troops.
The" Bill" itself with a few works thrown up by an
active enemy would assure him a base of operations.
From Selsea to Chichester is a capital road, fit for
the passage of artillery, &c., while from the city
itself to the foot of Portsdown is one of the best
roads in the kingdom, and the whole length—
some 21 miles—as level as a bowling•grecn. To
prevent anything of this kind taking place, Chi-
chester possesses but two 18-pounder field guns.
The commanding position of Portsdown has se-
cured for it an unwonted degree of attention, until,
from its having been hitherto only celebrated for
the magnificent panoramic views obtainable from
it' crest, both seaward and landward, it is now
likely to become as celebrated for the extent of its
fortifications. The fortifications proposed for the
purpose comprise nine distinct works, exclusive of

the lines scarfing the hill on each end or flank, and
mounting together 226 guns, requiring 2,260 artil-
lerymen to man them. The cost is ( stimated at
£500,000. Colonel Ross, Royal Engineers, and
Staff are already engaged marking oct the sites for
the forts, but ground has not yet been broken, nor
may the progress here be so rapid, perhaps, as has
been anticipated. Portsdown is one of the finest
positions in the kingdom to experimentalize upon,
but it can never be turned, as was at first thought,
into a second Torres-Vedras affair. The latter was
a rock, and Portsdown is chalk. If the position is
fortified, as at present contemplated, it must be
with the intention of holding it at some future
time, possibly in the presence of an enemy, and
would then afford hint a grand opportunity to dis-
play his skill in mining, The siege of Schweidnitz
took place in 1793, and the Prussians prosecuted
it for 63 days, the Austrians defending it ; 49
of these days, we are told by Straith, the autho-
rity we have before referred to, were passed in
a subterranean war. In like manner would
the possession of Portsdown-hill be contended for,
and the question naturally arises, is it a good
policy to erect a line of permanent forts when the
ground on which they must be erected offers such
facilities for mining operations and their conse-
quent destruction ? It has been stated by eminent
military authorities on such matters that the erec-
tion of permanent works of any great extent on
Portsdown can be but an ill-judged proceeding,
and that the only method in which the case can be
met would be by the construction of a sunk re-
doubt on the crest of the hill, in its centre, with
the entire crest scarped, in conjunction with the
proposed scarping and batteries on the flanks, a
subterranean passage to communicate with the
sunk redoubt. The same authorities contend that
an engine, covered properly with a blindage, and
fitted with a seven-foot borer, would run a gallery
in any direction in an incredibly short space of
time, and enable the assailant to blow any fort into
the air. Straith says in his work, " Chalk is the
best soil for mining, as the slow and troublesome
process of supporting the gallery with frames and
sheeting can be dispensed with. Eliptical shafts
and arched galleries will stand without support in
chalk."

Opposite to Portsdown, and on the crest of the
slight ridge at the entrance to the island, contain-
ing Portsmouth, with its Royal dockyard, its vast
storehouses and shipping, are the immense works
erecting for the protection of the island from an
enemy landward. The distance, as the crow flies,
is 2,250 yards. The greatest elevation of Ports-
down is 444 feet above high-water mark,
while the slight ridge on which the Hil-
sea lines are being constructed is only six
feet above high water. This causes the lines in
course of development at Hilsea to look somewhat
contemptible when viewed from the greater eleva-
tion, but a closer inspection does away with this
ideas, and proves it to have been in the character of
an optical delusion. At the foot of the hill lies the
village of Cosham, and from hence to Post-bridge,
the first approach to the lines, the ground has a
gradual ascent, the whole of the ground for 600 yards
between the hill and Hilsea, in front of the latter
position, being below high-water mark, and, con-
sequently, by simply cutting the sea-walls at high
water, the whole of the land in front to the extent
named could he inundated. The only possible ap-
proach to the position is by the main road from
Cosham, which may be likened to a causeway
amid broken ground, swamp, and salt lakes. This
will give some idea of the nature of the ground
intervening between the foot of Portsdown and
the new lines of defence at Hilsea. When com-
pleted, these works, entered by the road from Cos-
ham, just described, will present themselves in the
following order :—The railway and turnpike roads
enter the works at different points, and are the only
portion which can by any means be enfiladed by
an enemy's fire. The first obstacle met with in enter-
ing will be the channel connecting Portsmouth and
Langston harbours, 200 feet wide, and of sufficient
depth to allow heavily-armed gunvessels to pass
through, and which would materially assist in de-
fending the works, their guns sweeping the marshy
ground in front in all directions. Means will be
applied for retaining the water in this passage
during ebb tide.
Three wide and deep moats, together with two im-
mense hornworks, each of the latter of an equilateral
triangular shape, have yet to be passed before the
main line is reached. These outworks will have
casemates armed a la Haxo, with light pieces of the
same character of weapon as the main lines, where
it is intended fortheArnsstronggun to enter largely
into the armament. Passing these outer defences,
we enter by the double gates of the western bastion,
which is now receiving its earthen front and profile.
The bastion trace has three fronts, with exterior sides
of about 730 yards, the lines of defence being 500
yards long. The flanks of these fronts are casemated
a/a Haxo, and will contain 10 guns each. In the rear
of each gun is a bomb-proof chamber for 10 men.
These batteries will deliver a heavy flanking fire
over the Channel on the flanks of each bastion. The
base is 116 feet. The command of the line will
average 26 feet. The parapets of all the works ex-
posed to a direct fire will be 24 feet thick. The
whole of the works, with the exception of a portion
of the road and railway, as before stated, will be
perfectly defiladed from the fire of any batteries
that can be planted in any position in front or on
Portsdown. On the east and we end of the line
a demi-bastion casemated protects that part of the
work, and a continuation of the earthwork is car-
ried for some distance along the shore of each har-
bour. This latter it is not intended at present to
arm with guns ; still, it would seem necessary to
do so, especially on the Langston harbour face, as
an enemy advancing on the Chichester road might
seize boats at Havant, &c., as he came along, and,
crossing the harbour, take the works in reverse.
The top of the works will have a parapet for rifle
fire, the terre-plein of which will be well reversed,
with a slope of 2 feet to the rear. Along the entire
length of the main line, in its rear, is being con-
structed a military road for the supply of material,
&c. In the rear of this road a large sewer is in course
of construction, which will intercept the natural
drainage of the land in the roar, and receive the sew-
age from the new barracks building in the rear of all.
The magazines, 36 in number, are situated at inter-
vals under the main line. The greater portion of
the brickwork and masonry of the main line is com-
plete, and the line of earthwo ks to corer and con-
nect the whole has been fairly commenced, and in
parts, where the profile is complete, gives some idea
of the immense strength and solidity the whole will
possess when completed. 130,000 bricks per day
are now being laid on this portion of the line of de-
fences alone. About 1,200 men are also employed
upon them-500 in fixing the material, and the re-
mainder in preparing it. The late wet weather has
been pre-eminently calculated to try the great masses
of brickwork and masonry forming the casemates
for the flanking batteries of each bastion. A careful
inspection of the whole, however, proves the perfect
soundness of their construction, not a single crack or )
flaw being visible in any part. These works, forming
as they do one of the most important points in the
defence of Portsmouth, deserve an extra amount of
attention, and, as their profile has not yet been
formed, their apparent deficiency on certain points
may be pointed out. They now contain accommoda-
lion for 600 men, but by slightly raising the height
of their profile, and bringing the interior slope of
tho ',corks square with the base or ground plan,
sufficient space could not only be gained in which
to quarter all the troops proposed to be quartered
in the new barracks in rear of the lines, but also to
afford shelter to the whole of the inhabitants of the
hie new
island in the event of any bombardment by sea and
land. he
ni ea i barracks now
of naing underwbu theildin building forofttehe.
iroo
latworks, are entirely the t
unprotected, and
troops
i enfiladeis alsofirfrora intended anyto sptooirnett h In tlle
greaterse
portion of the
material required for war service in
the new lines.
tcaeisning seaward
t he
obparernae toks, an
too,
This concludes the defences of the port
by land. The proposed
d ecfee nn
are fully
reported in the Blue-book
taken before the National Defence Commission.
They consist of a series of heavy stone forts on the
Noman, Horse, Spit, and Stearbridge shoals,backed
by strong batteries erected on the Isle of \S ight