With regard to architecture, that strictly belonging to the office of the civil engineer is of the most simple character. The buildings should be laid out in the best manner, and the most convenient for their respective purposes, and thoroughly substantial. At the same time, their exterior appearance should possess a certain degree of symmetry and dignity, so as to impress upon the spectator the idea that they are thoroughly adapted for their purpose. The materials should be chiefly iron, stone, and brick; and timber should only be used when absolutely necessary. At the same time, although it is not altogether necessary, the civil engineer should have a thorough knowledge of the five orders of architecture, and the mode of applying them; the principles of constructing and equilibrating arches of all kinds must be thoroughly understood; and if he intends to combine the practice of domestic and public architecture with that which is only strictly necessary for civil engineering, then he must enter more largely into the subject, and study the different ancient and modern styles of building.
Surveying and levelling will also form an important part of his duties. In order to understand them it is necessary that he should know thoroughly plane and spherical trigonometry, and the calculations necessarily connected with them. He should also have a certain knowledge of astronomy, to enable him to calculate the tides and other phenomena connected therewith, and to be able to lay down correct charts of any harbour or sea coast, with the soundings, currents, and winds prevailing there.
Geology will form another important department of study, without which he cannot understand the nature of the materials that he will have to deal with, such as stone, lime, cements, earths, &c.; the angles at which they will stand in making deep cuttings and embankments; the best and most durable kind to be employed in any particular work, the proper mode of working it, and how to place it in the best position so as to resist the effects of the atmosphere or running water, the concussion of waves, &c., in the most effectual manner. The study of geology will further enable him to account for the formation of shoals and any given line of coast, together with the operation of the currents upon them, and the best mode of remedying their disastrous effects; also the best plan for designing and constructing harbours on each particular coast or situation.
Again, by having a thorough knowledge of the strata and formation of any given district of country, he will be enabled to ascertain where water may be found, and in what quantity; and if he practises mining, he will be able to predict with tolerable certainty where different kinds of minerals may be obtained, such as coal, iron, lead, copper, tin, gold, silver, &c., and the mode of working them to the greatest advantage.
In fact, geology combined with mineralogy he will find to be of most essential service in almost every department of civil engineering.
Embankments.—This is another department of engineering which requires a good deal of skill and judgment, particularly along an exposed open coast, where lowlands are to be protected against the encroachments of the sea. The first point is to select the line of embankment in such a manner that there shall always be in front of it a good foreshore, so that the force of the sea may be broken before it reaches the embankment; that is to say, where practicable, to have a certain extent of green or outlying marsh in front of it, so that the embankment when completed will seldom have a head of water to contend with at high tide of above six or seven feet. And even with this moderate depth at high water, when exposed to the action of a heavy gale of wind, there will for three or four hours be a considerable broken sea, calculated to do a great deal of damage, if the embankment be not properly constructed. Now, if the embankment have a good green foreshore in front, with sea slope of about 5 or 6 to 1, well sodded up, a facing of clay about 18 inches thick, 6 feet above the highest level of spring tides, the top being 6 feet wide, with back slopes of 2 to 1, with a back ditch 10 feet from the foot of the inner slope, the interior of the embankment being composed of sound earth well rammed or pressed together, so as to make it solid—an embankment of this kind will be able to resist such a pressure as we may ordinarily expect it to be exposed to.
There may be extraordinary cases where this will not be sufficient. When these occur it will be necessary to pave the surface with stone, about 9 inches thick, or with fagots. The former is, however, decidedly the best plan, as it will be permanent, whereas fagots are constantly rotting, and require renewal.
If the sea shows a tendency to carry away the foreshore, it must be prevented, by means of jetties so disposed as to collect the alluvial matter held by the sea water in suspension. These, if properly designed and constructed, will generally have the desired effect.
In cases where the water outside is deep and the sea face of the embankment may be exposed to a head of water of 12 feet and upwards, much greater precautions must be taken to guard against accident. The sea slopes of the embankment must be increased to 7 or 9 to 1, well faced with clay and paved with stone, having the foreshore in front well protected with jetties. In fact, no two cases will be alike: each must be treated separately according to the particular local circumstances, and therefore it is impossible to design a proper plan for any embankment without knowing all the local circumstances. The general principle is that the sea face of the embankment should never be less than from 4 or 5 to 1. In some particular cases a less slope will do, say 3 to 1. This, however, certainly depends upon local circumstances. The base of the outer slope should be particularly watched, and if any crack appears to be forming, it should be immediately stopped by jetties carried out as far as necessary. In forming embankments it is usual, when it can be done, to take the earth from the outside of the sea slope, but this should never be done within less than 10 yards from the base of the slope, and these “floor pits,” as they are termed, should generally not exceed 12 to 18 inches in depth, and be increased in width in proportion to the quantity of earth required for the bank; at every 10 or 15 yards, in the longitudinal direction, the earth should not be removed, but left to form small cross banks between the floor pits, so as to prevent any current being formed in them; thus these floor pits will soon be filled up by the alluvial matter brought in by the tide, when the outside slopes of the bank are neither exposed to the heavy lash of the waves nor to strong currents. Then if they are covered with good grass sods properly laid on and beaten into the face of the bank it may suffice, but not otherwise. If this should not answer the slope must be increased and, if necessary, paved with stone as above mentioned. When good clay cannot be obtained to face the bank, then the best of the earth that can be got must be employed, mixed with straw, well puddled with water, and laid upon the surface of the bank in a moist state about 18 inches thick, and then faced with stone about 9 inches thick, well rammed edgeways into it. In cases where it is necessary to protect any line of coast against the ravages of the ocean, the measures to be adopted will depend upon the form and geological character of the coast to be so protected, whether low flats and alluvial, or cliffs composed of rocks more or less hard, and easily acted upon by the waves, rain, and atmosphere. In the former case it will generally be found that the coast is surrounded by extensive flat sands, and that the water holds a large quantity of alluvial matter in suspension. The great object, therefore, should be to cause this alluvial matter to be deposited in such form and in such places as are best adapted to our purpose. Now this may generally be effected in an inexpensive manner, considering the object to be attained, by a series of jetties, either composed of stakes wattled together with fagots, or lines of loose stones disposed in such a manner that they shall break the rising and falling waters, and make them stagnant between the jetties, so that they may deposit their alluvial matter. In the first instance these jetties need not be raised more than two feet above the level of the sand, and when the sand or alluvial soil has accumulated up to the top, they may be again raised to a similar height, and so on until the soil in front of the coast has been converted into a green marsh; thus there will not only be formed a protection to the coast invaded by the sea, but fresh land may be gained in front of it and embanked from the sea. It is impossible to explain the precise disposition and direction of these jetties and works without a thorough knowledge of the locality, and such circumstances as its exposure to winds, tides, and currents. The principle however is to check the currents gradually, and in such a way as to prevent any strong current from being formed; for if a new and strong current should be created, not only will the alluvial matter not be deposited, but the works themselves will be carried away, and all the labour and expense will be wasted. It is generally advisable that such works should be commenced near the shore, and worked downwards towards the sea; thus, if they are properly managed, no deep pools or strong currents will be formed behind them; and the required process of filling or silting up will proceed regularly seaward, always increasing the protection required, and obtaining additional land as they proceed.
In some cases, where the sea is heavy, it may be necessary to have stronger jetties or works to relieve and protect the minor ones above described; but these should only be resorted to in places where the others are insufficient, or in greatly exposed situations; wherever the minor works will suffice, as they will in most cases if properly applied and constructed, the less heavy works are resorted to the better, as the great object is to lead not drive Nature; that is, to work with her instead of against her. By this means a few bricks and stakes will do a great deal more than far greater and more expensive works. So far as regards low alluvial coasts, these, if properly managed, will be found comparatively easy to deal with.
When we come to rocky coasts that are wearing away by the combined action of the sea below and the rains and atmosphere above, and where there is little or no alluvial matter held in suspension by the waters, that might be collected so as to form a protecting deposit at their base, then we must adopt a different system, but not altogether ignoring the other when it can be made useful. In this latter case we must secure the bases of the cliffs at least up to high-water mark by means of retaining walls, where the rock itself is not hard enough to resist the action of the sea. These walls need not be carried higher than absolutely necessary. In some cases a mere footing will do; in others, the wall may be carried up to half tide; and in others up to the full high-water mark; and although the rock may be naturally soft, yet if its surface be protected by harder stone, even of a very moderate thickness, it will be quite sufficient to resist further encroachment by the sea. As these retaining walls will be founded upon a base of solid rock, there is very little fear of their being undermined; therefore, when I said before that it would be necessary to carry these retaining walls up to high-water mark, it must be understood as applying only to those rocks that are easily abraded by the sea.
There is another point to be attended to. The base being secured, we must look to the cliff above. Here, from the effect of rains, the water frequently cannot get away, accumulates behind at the top, and sinks through the fissures, when partly by hydraulic pressure and partly by the effects of frost, large masses are detached and fall below; and as this is continually occurring, the progress of decay goes on increasing. Having secured the base, the next thing, where practicable, is to slope off the upper surface of the cliff, so as to prevent it from overhanging, and then to make a drain at the back to carry off any water that may lodge there. By these means, if properly carried into effect, the base of the cliff being protected against the sea from below and rainwater from above, there is every probability that it will be preserved, in all ordinary cases. In extraordinary cases additional measures must be taken to meet them upon the same principles. With regard to retaining walls of brickwork or masonry, these should be always in excess of strength beyond the pressure, whether vertical or lateral, that they may have to resist. When the pressure is simply lateral, then the mean thickness of wall built of masonry and brickwork—the mean thickness, generally speaking, of the main body of the wall—should be about one-fourth of the height, besides counterforts at the back at certain distances from each other, regulated according to the particular circumstances. These, upon the average, including the thickness of the main wall, will make the total mass to be equal to nearly one-third of the total height. My father frequently made these walls curved in the front as well as at the back, the front being struck from a radius whose centre was level with the top of the wall, and of such a length that the face of the wall should batter one-fifth of the total height; the back of the wall should be struck from a centre at the same level as the other, but a little longer, so that at the base the wall might be about 2 feet thicker than at the top, in addition to two or three footings of 6 inches each; and the base of the wall was made to incline backwards, according to the radius from whence it was struck.
These walls, when they are to rest upon alluvial soil, must be founded upon a platform composed of piles of a sufficient length and thickness, driven at right angles to the line of the foundation, until with the blow of a ram weighing 15 cwt. and falling 20 feet they will not move one-eighth of an inch. These piles should be driven in regular rows, longitudinally and transversely, about 3 feet apart, and hooped and shod with wrought-iron hoops and shoes. At the front, immediately under the tie of the wall, there should be a row of grooved and tongued sheeting piles driven close together, and to the same depth as the others, about 6 inches thick, having a waleing or longitudinal brace 6 inches thick and 12 inches wide, well bolted in each side of the top of the sheeting piles. The loose earth should be taken out to about a foot in depth, and the space filled in with stone or brickwork to the level of the pile heads, which should be carefully trimmed, then covered with sills about 12 inches square, well spiked down to them. The spaces between the sills should be well faced with brickwork, and the whole surface should then be covered with 6-inch plank, properly spiked down to the sills below. Upon this platform the masonry and brickwork of the wall should be built. The wall should be carefully backed up as it proceeds with sound earth or clay, or clay mixed with one-sixth of gravel or concrete, as shall be deemed most advisable. These curved walls, if properly constructed, are stronger and more economical than the ordinary walls.
In some cases, as in that of Sheerness, for example, the foundation is so bad that a totally different plan must be adopted. At Sheerness it was necessary that the base of the walls should be increased, distributing the weight over a wider area, so that each superficial foot of the superincumbent mass should have a larger bearing, thus greatly relieving the pressure over every part.
The foundation upon which the walls were built was as bad as possible, being composed of nothing but loose running silt and sand. Upon such a foundation walls of the ordinary kind would not have stood; my father therefore saw the necessity of designing some new construction, upon the principles above mentioned. He had previously adopted something similar for the docks at Great Grimsby, in Lincolnshire, in 1786, which design was carried into effect with great success. The walls at Sheerness and at Great Grimsby were built both upon the same principle, modified according to local circumstances. Sheerness docks were finished altogether in the year 1826, and they have stood ever since.
I believe that I have now enumerated all the chief points to which the education of a civil engineer should be directed. Whilst he continues in an engineer’s office, whatever business is brought before him, he should always endeavour to thoroughly understand the reasons for which such and such a work is proposed to be made, and the principles upon which it is to be constructed; and if he finds, according to his previous education, difficulties either in the principle or construction, he should modestly state his doubts to his superior; if no explanation is given, he has simply to do as he is ordered, making notes of his doubts, and when the work is carried into effect he will then be able to ascertain how far he was right or wrong. If the work turns out to be a failure, his previous calculations will show him that he was right; but if the work succeeds, his calculations were wrong, and he should carefully go over them again to ascertain his error. He should follow the same process when he has to design and carry into effect any work upon his own responsibility, and if he is in doubt as to any point, let him consult some one of his professional brethren in whom he has confidence. When he is consulted on similar occasions by another engineer, let him give his advice and opinion to the best of his power; by this means he will gain the respect of his colleagues, and every one will be ready to help him when required.
Let him be particularly careful about his estimates; and after he has estimated fully the probable cost of a work, let him add an allowance of quite 15 per cent. for contingencies, which in all engineering works are so numerous and varied that it is almost impossible to foresee them.
We should always recollect that the great object of all engineering works is to produce a fair return for the capital expended upon them, or, in other words, that they should pay. If, after due calculation, it is found there is no chance of that, they should not be undertaken; for although it may be very gratifying to the professional reputation of an engineer to have executed a great work, it is but a poor consolation to his subscribers to find that their money has been comparatively thrown away without any adequate return.
Upon these grounds, therefore, I think it is better that the engineer should confine himself strictly to his business, that is, of designing and estimating any proposed work in the best possible manner to ensure the object intended. Let those who are most competent ascertain whether there is a sufficient prospect of traffic to pay a good return for the required capital; and so long as the engineer executes the work for his estimate, he cannot be blamed if the work does not pay a sufficient return. In fact, the whole commercial value of a work depends upon its cost, and therefore it is so important that the estimate should be adhered to as closely as possible, for if this be much exceeded the commercial calculation falls to the ground, and then the subscribers have just reason to complain. Against this I have heard it argued that if correct estimates were always made, and the ultimate cost of many works was known beforehand, they would never have been carried out, although notwithstanding the increased cost they have finally proved to be very valuable. This is certainly to some extent true; many inventions and discoveries have ruined the original promoters, yet have ultimately conferred the greatest benefits upon mankind; and many enterprises that have ruined the original undertakers have greatly enriched their successors. Still there can be no excuse for an engineer knowingly underestimating the cost of a work; he is undoubtedly bound to make a fair, honest estimate of every work committed to his charge, so far as his judgment goes; having done that his duty is discharged; nothing further can be expected of him than to see that the work entrusted to his care is strictly carried into effect according to that estimate.
Since the summer of 1866 I have done scarcely anything. The great crisis and subsequent panic that occurred at that time paralysed the commercial world. I considered my advancing years (I was then seventy-two), and the great hazard and uncertainty of carrying on business, and thought it most prudent to retire. After the harassing and anxious life that I had led for so many years, I felt my health so shaken as to require complete repose. But I hope, if God spares me, to be still useful to the profession and my country, by completing a work on the drainage of the fens and lowlands of Great Britain, and hydraulics generally. I also design to write a history of engineering, enlarged from my Address to the Institution of Civil Engineers, and a life of my revered father. All these I have already sketched out, and I hope to complete them, if it please God to spare my life a few years longer.
My apology for the present work is this: I think it is the duty of everyone who has led an active professional life faithfully to record the various works in which he has been engaged, the failures as well as the successes, detailing the causes of both; for we frequently learn more from the former than from the latter. I believe I have in this book faithfully done this. From unavoidable circumstances I have been obliged to trust entirely to memory while writing these pages, having been totally precluded from consulting notes or memoranda of any kind; I hope, therefore, that any inaccuracies that may be detected by the reader will be pardoned, though I believe that in the main my statements will be found correct.
Like others, I have had to contend with professional jealousy; but I believe I have on all occasions done justice to my rivals, and I have never wilfully attempted to injure anyone. Naturally of a very sanguine temperament, I am but too apt to view things in a favourable light, and to judge well of those with whom I come in contact; as a consequence of this I have often been deceived by those in whom I have placed the greatest confidence. This sanguine disposition has been the cause of many disappointments; but it has also enabled me to bear up successfully against failure, and still to look forward with hope to the future. Whenever a misfortune has occurred I have endeavoured to forget it as soon as possible; I always called to mind the words of the great Duke of Wellington, who said, There is no use in looking back and brooding over the past; forget it, and apply your energies to the future, and do better next time. This many people either cannot or will not do; hence they succumb. Doubtless everyone has his trials, and some are much better able to get through them than others; nevertheless, a very little reflection will show that what is past cannot be helped, and that by brooding over misfortune we do no good, but only waste our energies and invite failure in everything else.
The motto of life should be, Forward! We must expect to be checked, thwarted, and baffled in our endeavours to attain success; but these obstacles, instead of totally arresting our progress, should serve only to increase our energy. Like a river, impeded in its course, in silence waits till its accumulated strength sweeps the obstruction from its path, and it flows on majestically as before—so should we make every difficulty we encounter add to our strength, instead of increasing our weakness. Nevertheless, since “’tis not in mortals to command success,” we may sometimes struggle in vain; and fortune ever against us, we may be overcome at the last; but even then we have this satisfaction—we have fought a good fight; we have done the best we could; we have done our duty to the best of our ability, and that is all that can be required of us. To do my duty has been my endeavour through life; and probably if I had adhered to it more strictly I might have done a great deal better. Nevertheless, little as I have done, I should not have accomplished half so much had I not kept that one object in view, as far as my physical and mental powers would permit; and this is no small consolation. The old motto, “Nil desperandum,” should be constantly on our lips, and should act like the spur on a jaded steed. Affairs are never so bad but they might have been worse, and they may generally be mended by energy and perseverance, and a determination to make the best of everything. We may not be able to accomplish all we aspire to achieve; nevertheless by refusing to yield to misfortune we shall escape the reproach of cowardice and faintheartedness. When we suffer a defeat, let us calmly consider the cause of it, and nine times out of ten we shall find that it is through our own fault; these lessons of experience should be carefully laid to heart, and serve for our future guidance.
I have never deemed wealth desirable for mere personal gratification, but only in so far as it would have enabled me to help others, to promote the advancement of science and the well-being of my fellow creatures; this would have conferred the greatest happiness upon me, but it has been denied by the Almighty Disposer of events, and most probably with justice, that it might be done better by other hands. I therefore humbly bow to the Almighty’s decision; and if I have done the best I could in His sight, I am amply rewarded. I, however, most deeply regret that I have not done more. I return my most fervent thanks to the Almighty that He, out of His great mercy, has allowed me to do the little I have done; and I most devoutly hope that He through His Son Jesus Christ will pardon my shortcomings; and I say with all reverence, Bless the Lord for all His mercies!
Dawlish, December 9, 1867.