Autobiography of Sir John Rennie, F.R.S., Past President of the Institute of Civil Engineers / Comprising the history of his professional life, together with reminiscences dating from the commencement of the century to the present time.

by Sir John Rennie

Besides oranges and lemons, St. Michael’s grows large quantities of Indian corn, wheat, barley, potatoes, and other articles, of which she exports largely to Portugal, and is considered the granary of the kingdom; her exports are much larger than her imports, and she receives back in return wine, oil, and manufactured goods. In fact, St. Michael’s is looked upon by the Portuguese as their most productive and wealthiest island. The population is extremely civil, hard-working, and industrious, and the upper classes are wealthy, enterprising, and energetic, and send some of the most talented deputies to the Cortes, who by their ability and perseverance attain the highest offices in the State; for example, the late Minister of Finance, Senhor Avila, who, although a rough subject, was yet possessed of great talents and integrity. The island also furnishes some very fine hardy sailors and soldiers; and I was told that the other islands of Pico, Fayal, and St. Mary’s, although not equal in extent or wealth, do the same.

On the 9th of October (1863) I again left London for Lisbon by one of the Royal Mail steamers, and reached it on the morning of the 13th following, and on the 15th, in the evening, I started in the packet for Ponta Delgada, which we reached on the morning of the 20th, after an agreeable and tolerably smooth passage. I found that some considerable progress had been made with the preliminary works; although these were not so far advanced as they might have been, in consequence of the Junta not having found the necessary funds. I had previously explained to them in written reports, that the more complete the preliminary works were 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, 210l. 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 200l., 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 20,000l. 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 2000l. 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 18,000l. 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 in between the outer and inner walls of the outer harbour had sunk in numerous places, and it was unsafe for any person or carriage to go over it; it was therefore imperative to take the whole of this out and refill it with proper concrete. The pavement also was completely worn out, so that we had to renew it. There was no means of supplying the ships with fresh water, or of extinguishing fires. It was therefore necessary to lay pipes with stop cocks and hoses round the piers and basin, connected with the main water-pipes in the town. The whole of the sewage of the town was discharged into the basin, and at low water it created a most offensive effluvia, which rendered this part of the town unhealthy; I therefore recommended that an intercepting sewer should be made round the basin, so that all the sewage should be diverted from the town and harbour into the sea, to the westward, and by this means it was carried away by the tide, and a great nuisance taken away from the town. There was no regular tide gauge to ascertain the exact rise and fall of the tide, so that the harbour light at night could not be shown at the proper time, neither could the day signal be hoisted to show when there was sufficient depth at the entrance. This defect I remedied by establishing a self-acting tide gauge in a well within the lighthouse at the west pier-head. The pole of this tide gauge was connected with a cylinder and a clock hand; on the cylinder was a roll of paper, and to the hand of the clock was attached a pencil, which, as the rod or tide gauge rose and fell, marked it on the paper; thus the rise and fall of every tide was indicated upon the paper, and the clock showed the time, so that the rise and fall of every tide was regularly registered and kept in a book from year to year. I also established barometers at different parts of the harbour, under lock and key, the latter of which was kept by the harbour-master; these barometers were set every morning, and the rise and fall was registered in a book, so that all the captains of vessels in the harbour could ascertain as nearly as practicable the state of the weather; rain gauges were also established, a regular account of the rainfall being registered. Before my time the trustees had got an admirable time clock, by Moore, for which they paid 200l., and Mr. Turner, one of the chairmen of the trustees, got another clock from Dent’s, which cost 105l. These two clocks were kept in repair by a competent person, and corresponded to a second with the Royal Observatory time at Greenwich, hence every captain of a vessel starting from Ramsgate could carry the correct time with him. Thus Ramsgate was provided with all the instruments for ascertaining the correct time, the state of the tides, together with the barometer, thermometer, the wind and rain gauges, and everything necessary to indicate the probable state of the weather.

All harbours ought to be provided with these instruments, and a regular journal should be kept, forming a careful record of the observations made from them. After the harbour was transferred to the Board of Trade I still continued as principal engineer, at the same salary, viz. 315l. per annum and travelling expenses.