Autobiography of Sir John Rennie, F.R.S 61

Autobiography of Sir John Rennie, F.R.S 61

should be stored during the periodical rains, to serve as a supply in

the dry season, not only for domestic purposes, but for irrigation,

navigation, &c.; the reservoirs should, in some cases, be covered, and in

others open, even to the extent of making them large lakes. They should

be provided with proper sluices and culverts, open or covered, as may

be required, and best adapted for distributing the water in the most

beneficial manner.

 

Having obtained a sufficient supply, the next point to be attended

to is, to take care that the water shall not be polluted: in order to

effect this, in all thickly-peopled districts the sewage should not be

discharged into the river or watercourses, but into separate, isolated,

and well-ventilated tanks, and then be deodorized by mixing it with

earth, or subjecting it to any well-known process for this purpose, and

the refuse should be distributed for manure; thus the sewage, instead of

being a nuisance, will become valuable for agricultural purposes.

 

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.

 

When President of the Institution of Civil Engineers, during the years

1845-6-7, I drew up detailed reports of the history of the profession

from its commencement in Great Britain up to that time, showing what had

been done in every department, by whom, and at what date. These reports

are published in their ‘Transactions.’ Subsequent presidents have to

some extent adopted a similar course; but with all due respect to them,

they have not taken that large and scientific view of the profession of

a civil engineer which it is imperatively necessary to adopt in order to

keep the profession up to that high tone which its importance requires,

not only for its own credit, but for the benefit of the world at large.

Perhaps there is no profession (with all proper respect to others) that

has conferred so much benefit upon mankind as that of the civil engineer.

Its objects are clearly defined in the two mottoes belonging to the

Smeatonian Society of Civil Engineers, which was the first of the kind

established in this country, having originated with Smeaton, Mylne,

and my father, namely, “_Omnia numero pondere et mensurâ_;” Ὦν φύσει

κρατοῦντες τέχνῃ νιχώμεθα. Up to that date the profession of a civil

engineer may be said to have been unknown in Great Britain; previous to

that time we were simply known as “_vulgar mechanics_”--men who toiled

with their hands, as masons, bricklayers, carpenters, blacksmiths, &c.

But those who so called us would have entertained a very different

idea of the “mechanics” if they had been forced to dispense with their

services. Let me ask how could the various and complicated operations

which alone render modern trade, and therefore modern civilization,

possible, be carried on without the aid of the mechanic, _alias_ the

civil engineer?

 

The object of the Smeatonian Society was merely a social gathering in

the form of a club, to assemble the members at dinner at certain times,