The Sun.
London, England, 1841-08-12 00:00:00

PLYmOUTII BREAKWATER.

" W. STUART, Esq., Superintendent of this Work, then
read the following paper :
" Gentlemen,—Before I proceed to the immediate sub-
ject of my paper, I may, perhaps, be allowed to state
that from the moment at which I first learned that the
eleventh meeting of the British Association would be held
at Plymouth, I purposed preparing a communication
upon the Breakwater to lay before it, for I readily ima-
gined that a communication respecting that great
national undertaking could not be but well re-
ceived. Had this, however, not been my determine-
`ion, I should have felt myself called upon, after
the recent papers which have been presented to
the Association in this and another of its sections,
to make some communication upon the subject ; for,
as the matter now appears before you, the present stone
Breakwater has on the one hand been productive of very
injurious results to this great naval and maritime port,
by causing a deposit within, and consequent loss of depth
of water of about five feet ; and on the other hand, not-
withstanding the great outlay on the
apart of the Go-
vernment in the construction of that Breakwater, it will
be entirely destroyed by submarine agency. But as to
thg correctness of these conclusions 1 shall presently say
a word. The importance attached to Plymouth as a
naval station, arising from the magnitude of its Dock-
yard, and other causes, gAye rise to the Breakwater.
In the early part of the year 106, the attention of the
Admiralty was directed to the subject. and in the
month of February in that year their Lordships
directed the late Mr. John Rennie, civil engineer, and
the late Mr. Joseph Whidbey, then Master Attendant
at Woolwich Dock-yard, to proceed to Plymouth to
survey the Sound. It is unneeessary- that I should say
a word upon the judiciousness of the selection thus made
of the parties who were to plan a Breakwater .for Ply-
mouth Sound. Mr. Rennie was then at the head of his
profession, and up to the period of his lamented death,
1821, maintained his well-earned reputation. Mr.Whid-
bey had had considerable experience as a Master in the
navy ; had sailed round the word with Vancouver, dur-
ing which he had made extensive surveys of harbours,
tides, kc., and for several years had been Master At-
tendant at Woolwich and Sheerness Dockyards. On the
lath of March, 1806, Messrs. Rennie and.Whidbey met
at Plymouth in order to carry out their Lordship's in-
structions, and on the. 21st of April they made a joint
Report to the Admiralty with the result of their.survey,,
and. at the same time submitted to them a plan for a stone
Breakwater, and gave their opinions upon several plans
which had been previously proposed for protecting Ply-
mouth Sound and Cawsand Bay, none of which, however,
had been prepared under the directions of the Board of Ad-
miralty. The plan proposed by Messrs. Rennie and
Whidbey consisted of a Pier or Breakwater across Ply-
mouth Sound, of 1,700 yards in length at the top, 1,000
of which at the middle part was to be straight, and 350
yards at each end was to incline to the straight part in
an angle of about 20 degrees, leaving an opening at
either end for the •passage of vessels, &c. The. top of
the Breakwater was to be ten yards in width at the level
of ten feet above the lower water of an ordinary spring
tide, and to have a slope on the south or sea side, of
three feet horizontal to one foot perpendicular, and on
the north or land side, one and a half horizontal to one
perpendicular. The work was to be constructed by
blocks of stone, thrown promiscuously into the sea, in
the line of the intended Breakwater, leaving them to
find their own base, and the topOrts to be composed of
a cut. stone pier. !-A?,77•.-
• .
This report and plan was very 'favourably received,
but owing to frequent changes in the Government and
other causes, the commencement of the Breakwater was
delayed, and it was not until the 22d of June, 1811, that
the order of his Royal Highness the Prince Regent in
Council was issued for that purpose. T,he necessary
steps were immediately taken to carry out that order,
and in the beginning of 412, twenty-five acres of lime-
stock rock, situated at Oreston, adjoining the harbour of
Catwater, were purchased for a sum of 10,000/. The
first stone of the work was laid on the 12th of August,
1812, after which vessels continued to discharge their
cargoes, consisting of stones of from half a ton to 7 tons
in weight, upon the line of the direction of the intended
work. By the 30th of March, 1813, a small part of the
Breakwater was visible at low water, and by the 30th of
July following the work was dry at low water to the ez-
,tent of about 720 yards. The work progressed, so rapidly
that in the month of March, 1814, first-Fate ships
of war were enabled to anchor in the Sound,instead of
in Cawsand Bay as they had previously done. In No-
vember 1814, it was determined to bring up the Break-
water to the height of 20 feet above low water of spring
tides, and to finish it with rubble instead of with a cut
stone pier as originally intended. In August, 1815,
1,100 of the 1,700 yards of the intended length of the
Breakwater were brought up above the level of low
water, spring tides. Up to this time 615,057 tons of
stone had been deposited. The first storm which mate-
rially effected the work, occurred in January 1837 ;
and in the month of November, 1825, another storm
occurred, far exceeding in violence any that had pre-
eeeded it since the work began. The wind blew from the
S.S.E. to S.W. and the tine rose seven feet higher than
the usual flow of spring tides. At this period, 1,241 yards
in length of the Breakwater were completed, of which 796
yards were overturned and deposited upon the northern
slope, during the storm (which lasted only a few hours)
leaving only 445 yards remaining not much damaged at
the east end of the main arm. The slope as left by the sea on
this occasion from low water upwards was about 5 feet
horizontal to 1 foot perpendicular and in some places ra-
ther more. It was therefore determined in April 1825,

to form the Breakwater regularly from the level ofJow

water, spring tides, with a casing of rough squared blocks
of granite and limestone on the top and on the exterioror
south side with a slope of 5 to 1, and on the inner or
north side with rough blocks of limestone with a slope of
2to 1. It was also determined to change the centre line
by placing it 39 feet 6 inches to the northward, so as to
leave the great mass of materials to seaward, and to in-
crease the width on the top to 45 feet. I may here remark
that although the Breakwater was so much affected
by this great storm, and considerable damage was sus-
tained by the shipping then in the harbour, yet the
generally received opinion was, that had the Breakwater
not been in existence, the shipping would have sustained
still greater damage, and the lower part of the town of
Plymouth been swept away. In 1830 it was found
necessary still to add to the south side, by depositing
about 60,000 tons of stone as a foreshore, fifty feet
in width from the top of the south slope at low water at
the west end, and 30 feet at the east end of the main
arm. In 1833 it was proposed to complete the extreme
western end of the Breakwater with a circular head of
solid masonry with an inverted arch as the foundation
of an intended lighthouse. In February, 1838, a storm
removed about 8,000 tons of stone from the foreshore at
the west end, and threw them over to the north side, and
disturbed a portion of the masonry, where it was uncon-
nected or in an unfinished state. A further extension
of the foreshore at this part was consequently agreed
upon. Another severe storm in November of the same
year, producing nearly similar results, occasioned the
construction of a buttress not only for the purpose of se-
curing the foot of the south slope, but also to afford
protection to the intended lighthouse, by breaking the
force of the sea, and preventing the stones composing the
foreshore from beating against the lighthouse. The force
of the sea at this part of the work is so consider-
able, that stones of 15 and even twenty tons have been
taken from low water, and carried over the top of the
work. The buttress as well as the work in progress
round the west-end at the foot of the slope at low water •
is composed of granite masonry, clove-tailed horizontally,
and vertically fixed with iron lewes or cramps, the rough
biocks formerly deposited being first removed by the aid
of a diving-bell, to the depth of from 3 to 5 feet below
• low water, and the masonry then laid at the above men-
tioned level. It was originally calculated that 2,000,000
tons of stone would be required to construct a Breakwa-
ter according to the plan of Messrs. Rennie and 'Whid-
bey, but from the various extensions of the work, the
quantity has necessarily increased, and the total amount
deposited since the commencement of the work on the
12th August 1812, up to the 31st July, 1841, was
3,377,068 tons. The greatest number of tons of stones
deposited in any one week amounted to 15,329, and the
greatest quantity in any one year to 332,407.
The estimated cost of the Breakwater, as originally
planned in 1806, was 1,013,900/., but this amount cannot
fairly be brought into comparison ith the actual out-
lay, owing to the frequent alterations which have taken
place in the mode of executing the work, aml the conse-
quent increase in the quantity of material:; required for
the purpose. The expenditure upon the whole untbr-
taking up to this period has nevertheless only amounted
to 1,111,7001.; and the cost of the Breakwater when
completed (including the Lighthouse) will not exceed
1,300,0001. I have mentioned the exact expenditure
upon the work because various erroneous statements
have been put forth in print and otherwise upon the
subject. In a recent publication it is said that three
millions of money have been already expended, and
but a: few days since it was stated in the course of the
reading of a paper in this section that three such
Breakwaters would cost six millions of money. The
lighthouse tower intended to be erected on the western
end of the Breakwater was commenced on the 22d of
February last upon an inverted arch, which had been
previously brought up from below low water of spring
tides, and is now in progress. It is to be of granite
14 feet in diatheter in the clear, and the centre of the
light will be 55 feet from the top of the Breakwater.
This lighthouse, when completed, will supersede the light
vessel now moored ut the west end of the Breakwater,
where it was stationed in 1813, since which time, al-
though strongly fastened, it has more than once broken
adrift. Having now briefly noticed some of the leading
points in the progress of the stone Breakwater, I will
refer to some of the Breakwaters which, prior to its
commencement, were proposed to be constructed of
other materials. One of these was to, be of cast iron,
proposed by an officer of the Royal Navy in 1804.
Others, two of stone and one of wood, were proposed in
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less determined upon the construction of a stone Break-
water. It is clear, then, that plans for iron and wooden,
as well as for stone Breakwaters for the protection of
Plymouth Sound, were submitted to the Government of
the day prior to the commencement of the present one,
although it has been stated that had a plan for a wooden
Breakwater been submitted to the Government a great
saving to the country might have been effected. Thirty
years have since elapsed, and my own opinion is now, as