By these means, regulated according to the particular circumstances of each case, the whole question, viz. economy of water, which is so very important in every respect, is solved. I have long endeavoured to make it clearly understood, but in England we are slow to move in a new direction. The enemy must be at our doors before we are prepared to meet him, and then we begin in earnest. Such has been the case with the water question: we carried drainage almost to the utmost extent, so that the rainwater was discharged into the adjacent watercourses and rivers with the greatest rapidity and was carried off to sea, and we thought not a moment that the day would come when we should want it. The universal cry was, “Only get rid of the water, and all will go on well.” At the same time all the sewage matter was discharged into the watercourses, the cry being, “Only get rid of the sewage, and our cities and towns will be healthy, and we shall hear no more of it;” little thinking that the streams would be polluted, and that water when most wanted would not be forthcoming, and that even the moderate quantity that could be obtained would be unfit for domestic purposes. The Thames and all the great rivers and streams were converted into common sewers, threatening to spread pestilence around them. The water that was to be obtained for domestic purposes was polluted to such an extent, that the malaria caused by the foul state of the watercourses was increased by drinking the contaminated water that we fondly expected we had got rid of. At last the public opened their eyes, and asked how all this had arisen; then commissioners of all kinds were appointed by the Government to investigate these important questions; and what is the result? Precisely that which I mentioned years ago, namely, 1. That means must be established for economizing water and for affording an ample supply at all times. 2. That all sewage matter must be diverted or be prevented from being discharged into the watercourses. 3. That as far as practicable the sewage matter must be utilized for manuring the land. All these three propositions, which constitute the whole elements of these important questions, are now being carried into effect by Acts of Parliament; better late than never, for if these terrible evils had been allowed to exist much longer the consequences would have been most fatal.
About four years ago I wrote two letters to ‘The Times,’ which were printed in that journal, embodying my views upon this subject in a detailed manner, according to the principles above described. I am extremely glad that at the eleventh hour the subject is beginning to be thoroughly understood, and it is to be hoped that now the proper remedy will be employed; it is contained in the principles that I have recommended for the last forty years. I may not perhaps claim the merit of the whole; but this I must say in justice to myself, that I have contributed in some degree to direct attention to the subject, and I most sincerely trust that, having been made conscious of its importance, the public will not be content until the question has been thoroughly sifted, and the evils complained of successfully remedied. Up to the present time neither compensating reservoirs for the due supply of water during the dry seasons have been made, nor, with a few solitary exceptions, has the sewage been excluded from the rivers, nor have the watercourses been properly improved so as to prevent inundations of the adjacent lowlands. In fact, the authorities have only just begun to get an idea of what is required to obtain an ample supply of good water; but the more they investigate the subject, the more they will find that only upon a right understanding of the principles above recommended can this supply be procured. Sewage matter has now been recognized as a fertilizing agent, and the only points undecided with regard to it are the best modes of deodorization, so as not to injure its manuring value, and the most suitable method of applying it to the land, whether in a liquid or in a solid state.
With regard to water for domestic use, considerable progress has been made: the water is conducted into covered reservoirs, where it is excluded from the action of the atmosphere; it is also filtered, so that all the alluvial and tangible vegetable matters are excluded; and the best method of separating from it those injurious ingredients with which it is chemically combined has made great progress. These, no doubt, are considerable advantages gained, but unless the means of obtaining an ample supply be used, the other advantages will be comparatively of little service. It is true they will be valuable as far as they go, but if there be a deficient supply of water, there will remain a great deal to be remedied, therefore it will be necessary to secure an ample supply by means of open reservoirs.
CHAPTER XI.
The Formation of Natural Breakwaters—The Society of Civil Engineers—The Education of a Civil Engineer—Some Hints on Practice—Estimating.
In the introduction to my work on ‘British and Foreign Harbours,’ I have suggested a method by which shoals formed by alluvial deposits in the open sea might be converted into effective breakwaters, so as to become harbours of refuge; or the means of removing them altogether. It is well known that many existing shoals form, to some extent, safe roadsteads at certain times of tide, e.g. the Goodwin Sands, the banks outside Yarmouth Roads, the banks off the coast of Holland, and many other places. These are generally formed off alluvial shores, where the meeting of opposing currents causes an eddy or line of stagnation, and the alluvial matter held in suspension is deposited, forming a bank, according to the extent, width, and direction of the eddy. In some instances, as in the case of deltas of rivers, and along coasts where the waters are densely charged with alluvial matter, these shoals, by continual deposit, are raised to the level of high water of neap tides, when a succession of marine vegetation appears on the surface, finally becoming a rich grass marsh; except under special circumstances, the land is seldom raised higher, and where there is no flow of tide the same result takes place at the medium level of the waters.
In other cases, as in the open sea, where the waters are exposed to violent agitation by the wind, these deposits not only rarely reach the level of high water, but, except under particular circumstances, seldom exceed the level of half-tide, and often the banks remain many fathoms below low water, though even in their lowest state they are far above the bottom of the sea. As all these banks are composed of alluvial matter, we can only ascribe the different levels, first, to the variable quantity of alluvium with which the waters are charged; secondly, to the degree of agitation to which the waters are exposed; and thirdly, to the velocity and extent of the opposing currents which produce the banks. Having thus stated generally the causes that produce these banks, I now come to my proposition, namely, the best mode of utilizing them for making harbours of refuge, or the method for clearing them away where they may be injurious.
With regard to the first, it is only necessary to increase the power of the depositing eddy by means of artificial works, to raise the banks to any height required; by this means they may be rendered permanent breakwaters at the least expense. Secondly, where these shoals are injurious they may be removed by diverting the course of one or both currents, so that the line of stagnation shall be destroyed; the action of the sea will then gradually remove the shoal. Thus we have the means in our power of converting these sandbanks into most valuable harbours of refuge, or of removing them where they are found to be injurious. This I do not pretend to call an invention, but simply an idea, and I am not aware that it has been suggested before. Modern engineers have not sufficiently directed their attention to the construction of harbours. It is a very simple affair to build piers or breakwaters of any extent, provided the requisite means are forthcoming, but it is a totally different thing to ascertain whether, after these works have been constructed, they will answer the purpose originally intended.