Search      Hot    Newest Novel
HOME > Biographical > Life of Robert Stevenson > CHAPTER XVII. EXTRACTS FROM EARLY REPORTS.
Font Size:【Large】【Middle】【Small】
    Wide range of subjects on which Mr. Stevenson gave advice—Reports on ruins of Aberbrothock Abbey—St. Magnus Cathedral, and Earl’s Palace, Kirkwall—St. Andrews Cathedral—Montrose Church Spire—Melville Monument, Edinburgh—Lipping of joints of masonry with cement—Provision for flood waters in bridges—Hydraulic mortar—Protection of foreshores—Cycloidal sea wall—Checking drift sand—Night signal lamps—Cause of heavy seas in Irish Channel—Sea routes across Irish Channel—Build of ships—Prospective increase of population—Tidal scour—Unscrewing of bolts by the waves—Cement Rubble cofferdams—Buoyage system—Observations on fog signals—Regulations for steam vessels—Notes on shipwrecks.

Judging from Smeaton’s well known “Reports,” to which all have access, we may conclude that the “professional advice” given by early Engineers was very generally accompanied by a fuller and less reserved discussion of opinion than is to be met with in the brief and technical Engineering reports of the present day. In early times, Engineers did not hesitate to express themselves freely on physics, ?sthetics, or commerce, provided their views had a collateral bearing on the subject under discussion, and this often added to the interest of their reports.

These early Engineers were also consulted on a much wider range of subjects than the Engineers of modern times. We know that the larger requirements of modern Engineering demand that its practice should be classified237 under distinct branches, such as harbours, navigations, water works, gas works, lighthouses, or railways, not to mention electrical and sanitary engineering, and other branches of modern growth, all of which cannot possibly be advantageously practised by any one member of the profession; for no one mind can grasp the theoretical knowledge, and no one life can compass the practical experience, to enable a man to attain eminence in all these departments of modern Engineering.

A biographical sketch of Mr. Stevenson’s professional life would, it seems to me, be incomplete if it did not convey to the reader some notion, however general, of the wide range of subjects brought under his notice, in these early times, and of his comprehensive and suggestive mode of treating every case on which he was professionally consulted. This object would be only imperfectly attained were I to restrict my reference to his reports to the examples given in the preceding chapters; for I have found in his numerous writings casual notices of a miscellaneous and fragmentary character, many of which seem to me to be interesting to the profession, and worthy of preservation, and I propose, in this chapter, to give a few of these extracts, without order of subject or date; and I think they will justify my remark as to the great variety and fulness of treatment to be found in the reports of early Engineers.
* * * * *

It appears, for example, that Mr. Stevenson was often called to advise on matters which were more related to architecture than engineering. Of this nature was his238 tour of inspection to the jails of England, in company with Sir William Rae, the Sheriff of Edinburgh, in 1813, referred to in a former chapter.

In like manner he inspected Aberbrothock Abbey, with Sir Walter Scott and the Sheriff of Forfar, in 1809, to advise as to preserving the ruins, some of the turrets being in imminent danger of falling; and after procuring a survey of the whole building he prepared a report, with plans and specification, which were submitted to the Barons of Exchequer, and the work was thereafter carried out under his direction.

He also reported in a similar way to the Sheriff of Orkney with reference to the repairs of the Earl’s Palace at Kirkwall, estimated at £500, and on certain alterations at the Cathedral of St. Magnus.

With a similar object in view he inspected and reported on the Cathedral of St. Andrews, and the steeple of the Church of Montrose, which was thought to be in danger, and the result of that inquiry was the present beautiful spire, built from the designs of James Gillespie Graham.

He was also associated with Mr. Burn in the Melville Monument of Edinburgh,—the preparation of the foundation,239 the rubble work for the tower, and the scaffolding and tackling for raising the statue were carried out under Mr. Stevenson’s direction; the whole architectural design being due to Mr. Burn alone.

The well known practice of what is termed “lipping” with cement the mortar joints of masonry exposed to the wash of water is described by him as new in his report to the Trustees of Marykirk Bridge, of 16th July 1812, where he says:—

“Upon carefully examining the face joints of the masonry of the south pier under water line, some of these were found not to be so full of mortar as could have been wished, and although Mr. Logan (the inspector of works) had taken the precaution to cause the joints to be covered with clay to preserve them from the effects of the water, yet this had not altogether answered the purpose, and hence the reporter recommended to the meeting of the 8th current to provide a few casks of Parker’s Roman Cement, to be laid to the breadth of three or four inches upon the bed and end joints under the low water mark of the remaining piers.”

In determining the waterway of his bridges, Mr. Stevenson invariably provided for prospective increase of flooding due to agricultural improvements, as stated in the following extract from a report made in 1811:—

“To preserve an ample waterway the north abutment is placed about twelve feet from the edge of the river,240 leaving a sufficient passage for the water in floods. A less waterway might perhaps have answered the purpose, but as the valleys through which the North Esk passes may come to be meliorated by drainage, and especially those districts of country on each side of the feeders which join the river, the facility with which the surface water may then escape must greatly increase the floods, and although their duration will be shorter, yet their rise must be proportionally higher.”

The following remarks on hydraulic mortar, made in 1811 to the Commissioners of Montrose Bridge, are interesting as showing the detail which he brought to bear on all his works:—

“The best mortar for water work is a mixture of Pozzolano earth with lime and sand, but the late interrupted state of commercial intercourse with the Mediterranean has for years past rendered Pozzolano so scarce an article as hardly to be procured on any terms. Your reporter has therefore been induced to make various experiments with preparations of lime and Roman cement, and finds that a mixture may be made which will set under water and answer every purpose. For this mortar the lime ought to be well burned, and put into casks when drawn from the kiln. It should be brought to the work as recently after being burnt as possible. This will be most readily attained by taking the lime from Boddam kilns. English lime is in general stronger and cleaner, but some of it brought for the purpose of241 agriculture is not so suitable for buildings as Lord Elgin’s lime. These limes, however, cannot be had very newly burnt, and it will be preferable to take lime from some of the kilns in the neighbourhood which are of good character. When brought to the bridge the lime should be kept under cover, opening only one barrel at a time; the shells must be pounded to a state of powder, and immediately before mixing it with the other ingredients it will be proper to sprinkle a little water upon it to dissolve any gritty particles that may remain amongst it.

“The sand for this work, though fine, must nevertheless be sharp; it must also be passed through a sieve, and cleaned of all impurities by washing, if found necessary. For ramming the joints and pointing under water, let equal parts of lime in its powdered state and of Roman cement be used, with one fourth part of prepared sand, but for the upper works the quantity of Roman cement in the mortar may be reduced to one third part.

“The mortar must be mixed in small quantities and quickly beaten up into a consistency suitable for the work. All white specks, which are apt to swell and spoil the joints, must be carefully rejected from the mortar.”

Some suggestive remarks on the protection of foreshores, made in 1812, in a report to Lord Rosebery, on his Lordship’s property at Barnbougle Castle on the Firth of Forth, are given in the following terms:—

“If the operation of the waters of the ocean be242 attended to in the formation of the shores, some useful hints may be gained. These shores will be found to be so many inclined planes, varying in declivity according to the tenacity of the matter of which they, are composed. Hence it is that the minute grains of sand and the light sea shell become a lasting barrier against the rapid river current and the tumultuous ocean, while the erect sea wall is levelled with the ground. For the truth of this it were needless to refer to the works of nature in different quarters of the world, or in distant parts of this country; it is only necessary to examine the shores on each side of Barnbougle Castle, where the beautiful beach, consisting of sand and shells, between the Cockle Burn and the sea, forms a complete defence to the low grounds behind it, while to the northward of the castle the massive wall is in danger of being completely thrown down. Without waiting to inquire into the causes which regulate these appearances, it will be more consonant to the business of this report to point out how their simple forms may be imitated and turned to advantage.”

In reporting on the defence of the lands of Trinity, on the Firth of Forth, Mr. Stevenson recommended the adoption of a cycloidal talus wall, which was executed under his direction in 1821:—

“In giving an opinion relative to the best mode of defending and preserving this property, the reporter observes that it fortunately happens that the beach is pretty closely covered with large boulder stones, which now form a kind of chevaux de frise in breaking the force243 of the sea, and making it fall more gently towards high water mark. Were it not that these stones are proposed to be employed in the erection of a more effectual barrier against the waves, the reporter would not fail to disapprove of their removal for any other purpose.
Fig. 20.

“The reporter proposes that a Talus wall or bulwark should be built of these boulder stones, roughly dressed and laid so as to form a cycloidal curve in the central part, as nearly as may be, as represented in the section with its tangents (Fig. 20). The properties of the cycloid as applicable to a sea wall in an exposed situation are very important. In particular, if compared with any other curve, in the same vertical line and down through the same points, it will be found of swiftest descent under similar circumstances, therefore the water in its rise must be proportionally retarded. The lower tangent to the curve alluded to also forms a wall towards low water, best adapted for admitting the sea to flow gently over it, while that connected with the upper extremity of the cycloidal part, tending towards the perpendicular, brings gravity into action against the rise of the waves.244 The practical execution of a wall upon this construction is simple, while the aggregate quantity of materials is less than for any of the curves of the conic sections of similar extent, and it seems upon the whole to be peculiarly applicable for the defence of the sea beach in question.

“If we examine the numerous works of this kind erected for similar purposes along this coast, we shall find that the general process or action of the waves is to undermine the seaward courses of the walls. In some cases, however, where due attention has not been paid to making up the backing of the face wall in a compact and firm manner, the central parts have been found to sink and give way. But the more common mode of failure is by the undermining of the seaward courses, arising from too sudden a slope being given to the face wall, which has a direct tendency to produce additional agitation in the waters at the bottom of the wall, by which the beach is excavated, and the foundation, being exposed to the wash of the sea, its destruction soon follows. If we attend to the distribution which nature makes of the matters composing a sea beach, unless where special local causes occur, we find them laid with a very gradual descent towards low water mark. The sands of Portobello, in this neighbourhood, form a striking example of this. Here small quartzose grains mixed with light sea shells prove, in their effects, a more effectual barrier against the overwhelming force of the waves than perpendicular and massive walls of masonry.”


Mr. Stevenson recommended Lord Palmerston to introduce the Pinus maritima major, as a check for sand drift, on his estate of Mullaghmore, in the following report, dated 21st July 1835:—

“During the reporter’s visit to Mullaghmore, his advice was also asked regarding the operations at present going on for the improvement of the land. He had then much satisfaction in viewing the interesting improvements of reclaiming bog lands, and checking the inroads of the sand flood or drift, by planting ‘bent’ grass upon the shores of this estate. The system of dibbling the bent grass, pursued by Mr. Lynch, is in the best style which the reporter has anywhere met with; and he has been so impressed with the national importance of this scheme, from the success already experienced at Mullaghmore, that he has already taken the opportunity of recommending this system as applicable to the entrance of Ballyshannon, and in other quarters, particularly to the Highland and Agricultural Society of Scotland.

“The question chiefly submitted to the consideration of the reporter, in regard to these operations, was the best mode of defending the margin of the bent grass towards the sea. For such purposes, buildings or fences of any kind are not only expensive in their formation, but are also in constant need of repair. Mr. Lynch seems so much at home in all planting operations that the reporter begs simply to bring under your Lordship’s notice the French mode of planting a species of fir (Pinus maritima major),246 which was originally suggested to the Government by the late M. Bremonteuil, Ingénieur des Ponts et Chaussées. This system has been extensively tried along the stormy shores of the Bay of Biscay, particularly in the district of Grave, at the entrance of the Garonne, where the arid and sterile sands have been covered with extensive forests, which thrive quite close to the water’s edge. From the climate and exposure of the shores at Mullaghmore, the reporter has no doubt of the success of similar plantations in arresting the progress of the sand flood. It is believed that Mr. Lawson, seedsman to the Highland and Agricultural Society of Scotland, is taking measures to import the seeds of the Pinus maritima major, with a view to trying it on some of the exposed sandy districts of Scotland.”

From the following extract of a letter from Mr. Kincaid of Dublin, who was Lord Palmerston’s Commissioner, it is interesting to know that the experiment was entirely satisfactory, proving that the Pinus maritima major is well adapted to the climate of the coasts of the British Isles:—

“The Mullaghmore plantations extend to about 200 acres. About eighty of these were planted twenty-five years ago. Some of the trees are thirty feet in height, and vary from that height to about twenty or twenty-five feet. The remainder were planted ten years ago, and are making fair progress. All the pine plantations from opposite Newtown Cliffony to Mullaghmore are in a most healthy condition, the trees making growths of from twelve to twenty inches each year. The storms have no bad effect on the south side of the great sand hill, but on its summit, and towards the west side, the spray and247 gales of the Atlantic will not allow the young trees to make any progress.”

In a report to the Trustees for improving the Queensferry passage, made in 1811, Mr. Stevenson proposes a set of signals as described in the following extract, his proposal being, in fact, the signal now in use on all British railways:—

“Upon the supposition of its being the intention of this Honourable Trust to have an establishment on the south side of the Firth similar to that which is now proposed for the north side, the reporter takes the liberty of observing that much advantage, as the Trustees know, might be derived by the public from a few simple and well appointed signals, both for night and day.

“Those intended for the day may be constructed upon a modified scale, after the common telegraphic method; while the night signals can be rendered extremely simple and effective by interposing at pleasure between the observer and the reflector a shade of coloured glass. By connecting these partial obscurations of colouring the light with an index that shall be understood on both sides of the passage, orders may be communicated in a very expeditious manner.”

In a report to the Right Honourable Viscount Cathcart, Commander of His Majesty’s Forces, made on Portpatrick harbour in 1812, he gives the following explanation of the well-known rough sea between Portpatrick and Donaghadee:—

248 “In describing the harbour of Portpatrick, it may be noticed that although the coast on which it is situated is not directly exposed to the Atlantic Ocean, yet the opposing tides of the north and south channels meet there and separate to flow up the Clyde and Solway Firths, which, independent of storms, must occasion a very considerable commotion in the waters of the channel between Portpatrick and Donaghadee.

“Accordingly we find that the sea has made a great impression upon the coast of Wigtonshire; and though the shores between Loch Ryan and the Bay of Glenluce consist chiefly of whinstone (the greenstone of mineralogists), which is one of the most indestructible rocks we have, yet the figure of the coast is indented with many small cuts or creeks, and rocks are all along the shore found jutting into the sea. At the head of one of these creeks, which is about a hundred fathoms in length, and thirty fathoms in breadth, the harbour of Portpatrick is situated between two insulated rocks, upon one of which the piers are built, the harbour being formed by an excavation, chiefly in the solid rock.”

In the same report he states the relative advantages of various routes of communication across the Irish Channel:—

“A further extension of the intercourse between Scotland and Ireland could be made with much advantage to both by a regular establishment of packets between Ardrossan, Troon, or Dunure in Ayrshire, and Larne in the county of Antrim. Between the two last places,249 viz., Dunure and Larne, the distance would only be about sixty miles, being ten miles shorter, and unquestionably much safer, than the passage from Holyhead to Dublin.

“Under all the views of this subject, from the greater contiguity of Portpatrick and Donaghadee than of Lochs Ryan and Larne, and the former places having more immediate access to the open sea than the latter, and also from the intercourse being now fully organised by long establishment, it were perhaps better, even at a much greater expense, to continue the present system than to change it. Portpatrick harbour may be rendered incomparably better by the plan now proposed, and Donaghadee is also capable and stands much in want of improvement, by an extension of its piers and the erection of a permanent light to direct the packets into the harbour under night.”

In reporting to the Royal Burgh of Dundee as to the improvement of the harbour in 1814, Mr. Stevenson takes occasion to introduce one of those collateral questions to which I have referred:—

“It is curious to observe the changes and to trace the progressive improvements which have taken place in the form and build of ships. When we contrast those of early navigators with ships of modern times, among the many alterations, none seems more striking than the difference of............
Join or Log In! You need to log in to continue reading

Login into Your Account

  Remember me on this computer.

All The Data From The Network AND User Upload, If Infringement, Please Contact Us To Delete! Contact Us
About Us | Terms of Use | Privacy Policy | Tag List | Recent Search  
©2010-2014, All Rights Reserved