Autobiography of Sir John Rennie, F.R.S 57

Autobiography of Sir John Rennie, F.R.S 57

made, and the larger the scale on which the operations were conducted,

the sooner the harbour would be completed, and the greater would be the

economy. I have already observed that the Government had approved of

a certain plan for the harbour without consulting me, and that it had

simply confided to me the charge of carrying the design into effect.

However, I felt it my duty to consider the plan more maturely, so as

to ascertain how far it was likely to answer the object intended; as,

for example, whether the estimate made was sufficient for the purpose,

and whether it could be done within the time stated. I could not at

first do this, because I had not had time sufficient to investigate the

local circumstances; however, upon my second visit, the experience of

my former one, combined with the observations which Mr. Plews had made

in the meantime, enabled me to master the subject; and upon carefully

considering the plan adopted by the Government, and comparing it with

the local experience which I had now obtained, I felt convinced that the

design would not effect the object proposed. Vessels would neither be

able to enter nor depart during the most dangerous and prevalent winds,

without the risk of being shipwrecked; neither could those vessels lying

in the harbour be considered safe. The plan was deficient in all the

qualities necessary for a good harbour; as regards the expense, it would

cost at least more than double the estimate; and as to the time, it

would be extremely difficult to state when the works would be completed.

Having clearly satisfied myself upon these points, I felt it my duty to

inform the Junta, so that they might report the same to the Government.

The Junta received my remarks very cautiously, and said that several

objections to the plan adopted had occurred to them; however, they did

not pretend to give any opinion upon the subject, and they requested

me to make a full report upon the plan adopted, together with all my

objections, and the cost of carrying it into effect. They also requested

me to prepare a new plan, according to what I conceived best adapted to

the local circumstances; also an estimate of the cost of carrying it into

effect; and said that as soon as they received them they would send them

to the Government, and would communicate to me their decision as early as

possible. This I accordingly did upon my return to England.

 

This report was submitted by the Junta to the Government, and it was

decided that the plan I proposed was the best, and the Government ordered

it to be carried into effect. This decision was very gratifying to me,

for I was strongly convinced that I was right, and if the Government had

decided otherwise I felt that there was no alternative but to resign

my situation. The works were therefore ordered to be proceeded with

according to the new plan that I recommended. The Junta before I departed

arranged with me that the contract for my services should be limited to

five years from 1861, although I was previously informed that it should

only be for four years, the sum for my remuneration being the same for

five as for four years; this was certainly a loss to me, but I did not

wish to make any difficulty about it, as I was anxious that my plan

should be adopted.

 

My design consisted simply of one mole or breakwater carried from the

west side of Fort St. Braz, and in such a direction that no eastern pier

would be required, as the opposite shore of the bay would answer that

purpose. The mole consists of two arms, one at the shore end, 2000

feet long, and the outer end from 800 to 1000 feet long, with ample

depth within from 40 to 50 feet, and covering a water space of nearly

double the extent of the old plan. This new mole when finished will

have a strong promenade stone parapet 20 feet above the level of high

water, and a roadway below 40 feet wide, lined by a quay wall on the

inside, alongside of which the largest vessels may approach and take in

and deliver their cargoes at all times. Railways will be laid along the

quays, and cranes worked by steam will travel along them for loading and

unloading the vessels.

 

This mole is now advanced outwards about 1600 feet, and if the Junta had

only followed my advice, it ought to have been finished by this time.

I always calculated that after the first year, when the whole of the

works were in full operation, from 1000 to 1200 tons of stone should be

daily deposited, whereas, upon an average they have not done half that

quantity, in consequence of their not employing sufficient plant in the

shape of waggons, trucks, cranes, locomotives, tools, &c.; however, that

is their fault, not ours. I have constantly made reports pointing out

these deficiencies.

 

The quarries having now been opened, railways laid, and a sufficient

number of locomotives, waggons, and trucks having been provided for the

present, I proposed to the Junta that they should commence depositing

stone on the line of the great mole. The laying of the first, as

mentioned before, was simply a matter of ceremony, as they were really

not then in a position to commence the actual work. The Junta approved of

my proposal, and accordingly, two days before my departure, this ceremony

took place. About six waggons laden with blocks from two to five tons

weight were drawn by one of the locomotive engines from the quarries

to the end of the staging or platform in the line of the mole, and

were there deposited with great _éclat_. The locomotive then returned

with the empty waggons and brought six more, which were deposited in

the same manner, and this operation continued throughout the day. As

this mode of conducting the harbour works had never been before seen

on the island, it created much interest and astonishment amongst the

natives, and the ladies were particularly amused by taking a ride upon

the locomotive engines. I simply observe once for all that this mole was

to be constructed by depositing, from open staging in the line of the

mole, blocks of rough stone varying from a quarter of a ton to 10 tons

in weight, when they could be obtained. These blocks being deposited in

the sea, the waves would soon drive and consolidate them together, until

after a time the mass becomes immovable; in fact, the sea is the workman

or mason to arrange the stone deposited in such a manner that it shall

become fixed in its place; therefore, during the operation the more and

heavier the storms the better, the great point being that the stone shall

be carried out and deposited in such masses that the sea shall not break

through it, but merely act upon it, by drawing down the exterior or sea

slope to such an angle that it will stand after the heaviest storms. Now

my father, who commenced this system at the breakwater in Plymouth Sound,

and in other places, found that the sea slope of a mole or breakwater

constructed in this manner would stand an inclination of about 5 or 5½ to

1 for every foot perpendicular, and 1 to 1 on the land side, as I have

mentioned in a former chapter.

 

Throughout all my experience I have found the same, therefore the

breakwater at Ponta Delgada was founded upon this principle. Five lines

of railway of the 7-feet gauge have been carried out upon the staging,

so that the top has a width of fully 50 feet; and as the works proceed

outwards another will perhaps be added, if circumstances require it,

which will make the width 70 feet. By keeping up a constant supply of

stone, there will always be sufficient for the waves to act upon until

the sea slope has attained its ultimate point of repose. As fast as

the large blocks of stone are deposited and washed into their place,

great quantities of quarry rubbish are supplied to fill up the minor

interstices and render the whole mass more solid, until the slopes are in

a fit state to be regularly formed and paved for receiving the parapet.

 

For some years there had been constant complaint from merchants and

shipowners that they were taxed for Ramsgate harbour when their vessels

never did or could use it. These continued complaints, so often repeated,

at last had effect, and Parliament decided, in the year 1861, that the

passing toll of Ramsgate harbour should cease, and that only those

vessels that used it should pay, according to a certain tariff. The

trustees under whose direction the harbour had been made and maintained,

complained to the Government that without the passing toll they did not

see from whence funds could be derived to maintain it in a proper state

of efficiency, and therefore they requested to be relieved of their

responsibility, and tendered their resignations, which were accepted by

the Government, and an Act of Parliament was passed in the year 1862

relieving the old trustees from their trust, repealing their Acts of

Parliament, and vesting the harbour, all its funds, and responsibilities,

in the Board of Trade. I succeeded my father in December 1821 as

engineer-in-chief to the harbour, at the same salary, namely, 210_l._

per annum, which included travelling and office expenses of every kind,

the trustees paying the salary of the resident engineer themselves. The

harbour was in a very dilapidated state, in fact, it almost required

rebuilding, when it came under my direction, and monthly visits of two

and three days were necessary, besides attending the Board in London

once every fortnight examining accounts, correspondence, reports, and

plans, all of which required a good deal of labour and responsibility,

and which, if paid for according to the usual professional scale, would

have amounted to at least treble the sum of 200_l._, or more; but

considering the appointment to be permanent, and that upon retirement

I should be entitled to an adequate pension according to my years

of service, I thought it better not to decline. In the year 1822, a

committee was appointed by the House of Commons to investigate Ramsgate

harbour and everything connected with it. Mr. Wallace, afterwards Lord

Wallace, was chairman of this committee; he made a searching inquiry, and

found nothing wrong. I was examined at great length touching all works,

the mode of managing them, and what would be the total cost of doing so.

The cost it was extremely difficult if not impossible to state, for the

greater part of the works were under water, and failures and accidents

were constantly occurring without any previous warning, so that what was

sound one day was in ruin the next.

 

As an example, I may mention the west pier-head: this upon examination

carefully from above appeared quite sound; not a crack could be seen

above low water. It is true that the projecting basement floor of the

lighthouse, which was not properly connected with the lighthouse tower

itself, and was little more than a mere shed, showed a slight subsidence,

but this outer part of the lighthouse was in no way connected with the

outer walls of the pier head; in fact, it rested upon the chalk filling

between the outer walls and the lighthouse. Now this chalk filling might

have subsided, by some leaks through the outer wall of the pier head,

without denoting any serious defects in the pier-head walls; however

the walls fell, with little or no warning, and the consequence was that

it was necessary to rebuild the whole pier-head, and the lighthouse

also, at a cost of nearly 20,000_l._ To a certain extent the same

thing occurred at the east pier-head; but this I observed in time, and

completely secured it at a cost of 2000_l._ The whole of the inner walls

of the east and west piers were completely undermined, although from

above they showed no signs of failure, and I was obliged to underpin them

to a depth of from 10 to 12 feet below low water of spring tides. The old

wooden sluices were worn out; and these it was necessary to replace. The

main entrance from the harbour to the basin was in such a dilapidated

state that it was necessary to take it down and rebuild it; this cost

18,000_l._ The quay walls of the inner basin were fast going to decay;

and I was obliged to take them down and rebuild them. All the filling