Autobiography of Sir John Rennie, F.R.S 59

Autobiography of Sir John Rennie, F.R.S 59

that if he had lived he would have recommended cofferdams instead of

the diving bell. I consulted my brother George upon the subject, and he

was of the same opinion. We resolved to recommend that the remainder of

the works should be completed by cofferdams, and the Admiralty approved

of our recommendation. Messrs. Jolliffe, Banks, and Nicholson therefore

undertook the contract for these works at the sum of 845,000_l._, and

gave ample security; and they were most successfully finished for the

sum of 854,000_l._ in round numbers, or at about 9000_l._ beyond the

contract price, our estimate being nearly 900,000_l._; so that they were

actually completed for about 45,000_l._ below our estimate, and fully

three years sooner than they would have been if the diving bell had been

used. Of course the real merit of these works is due to my father; but

I claim some credit for having successfully carried them into effect,

for if any failure had taken place--and there was very great difficulty

and risk--I should have been blamed for it, and probably been ruined at

the outset of my career, as the whole responsibility rested with me; my

brother never went near them.

 

III. I finished the Chatham dry docks, commenced by my father, at the

cost of 100,000_l._ In these there was nothing remarkable; after those of

Sheerness they were much less difficult, although of a somewhat similar

kind.

 

IV. The next great work was the finishing of the great breakwater in

Plymouth Sound. The chief merit I claim for this is in adding the

benching or berm on the outside, at the base of the sea slope, which

breaks the sea before it reaches the slope and prevents it from acting

injuriously upon it. I also claim a certain portion of the credit

for arranging and executing the paving of the upper surface, and the

dovetailed masonry of the two ends of the breakwater.

 

V. The design and execution of the Royal William Victualling

Establishment, at Stonehouse, near Devonport, I claim entirely as my

own, with the exception of the machinery, for which my brother George is

entitled to an equal share of credit with myself. This establishment,

including the cost of the land, amounted, I believe, to between

600,000_l._ and 700,000_l._

 

VI. The great basin, two building slips for first-rates, mast slip, and

the river wall in front, at the Royal Dockyard at Woolwich, costing

340,000_l._

 

VII. In company with Mr. Joseph Whidby, Mr. Walker, and Captain

Fullerton, of the Trinity House, I made a report for removing the bar,

by means of dredging, at the entrance of Portsmouth harbour, upon which

there was only 13 feet at low water of spring tides, which we estimated

at 55,000_l._; and it is singular that this important work was never

carried into effect until many years afterwards, when it proved to be

completely successful as far as it went. The bar was lowered 5 or 6 feet,

and it might be lowered 8 or 10 feet more, so as to enable the largest

class of vessels to enter and depart at low water of spring tides, which

would be of the greatest possible advantage to the public service; and

although the Admiralty have not carried the dredging far enough, still

there is now 18 feet at low water of spring tides, which enables the

largest class of vessels to pass the bar at half tide, instead of only

at high water as before. This fully proves the value and correctness

of our joint report; it only now requires that our recommendation

should be carried further, and there can be little doubt that it will

be successful. This great national harbour will be rendered accessible

at low water, and it ought to be, particularly after the enormous sums

that have been expended upon it, for unless the depth over the bar is

increased all improvements will be comparatively valueless. Mr. Murray

and myself wrote a joint report to the Admiralty, recommending that, in

order to assist the dredging operations over the bar, a sluice should

be erected across the entrance to Langston harbour, with the gates or

doors of the sluice pointing inwards, so that at high water they might be

shut, and all the water, or so much of it as might be required, should be

sent through Portsmouth harbour at ebb tide, to assist in scouring down

the bar. Of course, in order to render these works effective, it would

be necessary to enlarge the connecting channel between Portsmouth and

Langston harbour, so that all the Langston tidal water should flow out

through Portsmouth during the time of ebb.

 

The Admiralty up to the present time have not adopted this report. They

must, however, in order to preserve the requisite depth over Portsmouth

bar, do either the one or the other, or both; that is to say, they must

increase the dredging operations, or send more tidal water over it, and

the latter can only be obtained from Langston; as this harbour is of

little commercial value, supposing that any partial silting up should

take place, the depth could be restored by dredging; but if both the

dredging of Portsmouth bar and the additional quantity of tidal water

from Langston harbour should be resorted to, the bar might be kept down

to the depth required, and Langston would not be injured. If these two

operations are skilfully conducted, so as mutually to assist each other,

the result will be successful, and this success is the more necessary,

in consequence of the quantity of land which is now being reclaimed from

Portsmouth harbour for the new works.

 

VIII. The great flour mills and biscuit machinery at the Clarence

Victualling Yard, Portsmouth, were designed and executed by my brother

George and myself. The idea of the bread apparatus was proposed by M.

Grout, and worked out by ourselves. The great flour and biscuit mills at

Deptford were also designed and executed by my brother and myself.

 

IX. The Thames Tunnel shield; the rolling machinery of the Bombay, the

Calcutta, and the Mexican mints; the machinery at Constantinople for

manufacturing small arms; numerous locomotive engines and tenders for

different railways, amongst them the ‘Satellite,’ for the Brighton

Railway, which was one of the first that travelled at the rate of 60

miles an hour. The engines and machinery for several of Her Majesty’s

vessels of war, amongst which may be mentioned the ‘Bull Dog,’ the yacht

‘Elfin,’ and others; four iron vessels, engines, and machinery for the

Russian Government for the Caspian Sea, the first that were ever placed

there; two yachts for the Emperor Nicholas; the ‘Vladimir’ frigate; two

large screw vessels of war for the Baltic; three also for the Black Sea;

several for the Danube Company; cranes, sugar mills, diving bells, and

machinery; gantry cranes for the mahogany roofs of the West India Docks;

spinning and all kinds of machinery, from the year 1821 until the year

1852.

 

X. The first sea-going screw vessel that was constructed, namely, the

‘Archimedes;’ and also the ‘Dwarf,’ 1839, the first screw vessel of war

that was introduced into the navy.

 

XI. I recommended that the use of the Cornish high-pressure condensing

system should be introduced into the steam-vessels of the Royal Navy.

At that time they were entirely upon the system of Boulton and Watt,

when steam was only employed to the extent of 5 lb. pressure upon every

square inch. Now it was well known that the intensity of the power of

steam increased in a much greater ratio than the additional quantity of

fuel required to raise the temperature, so that high-pressure condensed

steam was much more economical than low pressure. There was a good deal

of prejudice against it, in consequence of the decided objections of

Boulton and Watt, and therefore it was not adopted at the time, but by

degrees this prejudice has been overcome, and now steam of 25 to 30 lb.

is employed in the Royal Navy, with great advantage and economy.

 

XII. I may also say that I was the means of introducing oscillating

engines into the navy. These I believe were invented by a Mr. Witté,

of Hull, but in consequence of the extreme accuracy required in making

them, and some degree of prejudice against the vibratory action of the

cylinder, this very valuable invention was laid aside. The able and

ingenious Mr. Maudslay took it up, but was dissatisfied with it, and

abandoned it. Mr. John Penn, who had a small establishment for making

machinery at Greenwich, then adopted it, and commenced manufacturing

these engines upon a small scale for the steamboats on the Thames. He

improved on the idea, acquiring the greatest experience in constructing

the engines, and he was convinced that they could be made upon any scale

with equally successful results. It happened about this time that the

Admiralty required new engines of greater power for their official yacht,

the ‘Black Eagle,’ whose speed averaged little more than 8 knots an

hour, and they applied to Boulton and Watt, who had made the old engines

for the ‘Black Eagle.’ They said they could easily make more powerful

engines, but that these would necessarily be heavier, and sink the vessel

lower in the water, when the resistance would be so much increased that

very little additional speed would be gained, and therefore it would be

better to have an entirely new vessel. The Admiralty did not wish to

incur the expense, and the matter was likely to fall to the ground. Penn

heard of this, and, quite uninvited, sent in a tender to make new engines

for the ‘Black Eagle,’ double the power of the old ones, of the same

weight, and occupying the same space, for a sum, not, I think, exceeding

the cost of engines of the same power on the old method. He further

offered, if the Admiralty officers were not satisfied, to take them out,

and replace the old engines at his own expense. I happened to be present

upon other business with the Comptroller of the Navy, Sir Thomas Byam

Martin, when Penn’s tender was sent in, and after reading it he threw it

to me, and said, “Rennie, what do you think of that; should I accept it

or not?” I read Penn’s tender carefully, and knowing something about the

oscillating engine, and having a good opinion of it, I said I thought he

should accept it. “Then,” said he, “I will do so, and if it turns out

badly you shall have the blame.” “Very well,” I replied, “if it turns out

badly I will take the blame.” Penn’s offer was accordingly accepted. The

engines were made and fixed on board; all the conditions of the tender

were fully complied with, and the Admiralty were perfectly satisfied

with their bargain. From that time forward Penn became one of the chief

manufacturers of the Admiralty engines, and has continued to be so up to

the present time.

 

The harbours which I made are described in my work on ‘British and

Foreign Harbours’; they were a portion of Kingstown, in Dublin Bay;

Donaghadee, Port Patrick, Port Rush, Warkworth, Sunderland, East

Hartlepool, Whitehaven; nearly rebuilding Ramsgate harbour; Ponta

Delgada, in the Azores. I designed harbours for Oporto; the Mattozenhas;

Viana, Aveiro, Figuera, and St. Ubes, for the Portuguese Government; also

for Douglas, Castleton, Peel, Ramsey, and Laxey, in the Isle of Man,

for the local authorities; and Redoubt Kalé, in the Black Sea, for the

Russian Government.

 

XIII. London Bridge; Hyde Park, Kensington Gardens, and Staines Bridges,

besides finishing those at Crammond and New Galloway, designed by my

father.

 

I laid out and carried through Parliament the Brighton Railway and the

Black wall Railway, in 1838; also the Manchester and Liverpool Railway,

in conjuncti