1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



313 



wisliet) to know the alteration we proposed to make, and I submilted to them 

 a section of a differently formed sewer, Ihe sides beinf; arched as well as Ihe 

 top and botlom— a similar form to that adopted by the Finsbury division, but 

 rather more round ; 1 thought this necessary, in consequence of the extreme 

 wetness and want of solidity in the ground. Some discussion arose with tlie 

 commissioners on that question; and it was repeatedly urged that the ex- 

 pense of such experimental sewer would be borne entirely by my employer, 

 but that in the event of its being found inadequate it should be taken up and 

 replaced by any other they might require, at our cost. It ended, however, 

 in their refusing to allow any alteration to be made. Immediately afterwards, 

 feeling that the ground was our own, and that we had a ri^ht to make ex- 

 periments upon it without reference to the commissioners, we commenced a 

 sewer of a new form, intending, if our experiment succeeded, to call Ihe at- 

 tention of the commissioners to the subject, and to request their inspection. 

 One day, however, during the progress of this experimental sewer, we received 

 a notice from the commissioners, slating that they understood we were mak- 

 ing a sewer of different form from that prescribed by their regulations, ami 

 cautioning us from making such a sewer, because if made in that form they 

 should not adopt it, if required so to do. We paid no attention to that no- 

 tice at tlic time, not intending it to form a part of the permanent seiver, un- 

 less they might be induced to adopt it in the event of success. We shortly 

 afterwards received another notice from them, enclosing an extract from their 

 Act of Parliament, 47 Geo. 3, cap. 7, giving them pouer to "prostrate, de- 

 molish, or put down," a sewer built contrary to their rules, charge us with 

 the expenses, and otherwise punish us. As we were not disposed to get into 

 a collision with them, we abandoned that sswer, and have since built Ihe 

 sewers in Ihe form prescribed by theiii, and they stand perfectly well. 1 ap- 

 prehend that arises from the altered condition of the giouiid, for in the course 

 of these alterations the ground has been very much improved ; it is now dry : 

 whereas at the time we commenced, it was very full of water. Tlie sewer is 

 built in mortar, and the section of the present one is Ihe same as the seciion 

 of the original one. In the course of the examination of the sewer after its 

 failure, a singular circumstance presented itself: Ihe footings in several 

 places were forced upwards, the position of the bricks at the sides of the sewer 

 being canted upwards. 



" Do you conceive the footings add to the stability of the drain ? Decidedly 

 not ; I think they weaken it very materially. They prevent the pressure of 

 the earth being distributed equally over the sewer ; I conceive that a most 

 important condition to be considcreJ in the building of a sewer is that the 

 resistance afforded by the sewer should be equal, and in the opposite direction 

 to the pressure to which it is submitted ; there is no great dilficully in ascer- 

 taining the forces operatirg upon .sewers; they vary in direction and extent 

 as the degree of mobility of the ground: you might imagine the ground to 

 be so fluid that the pressure should assimilate itself to that of Hater : in pro- 

 portion as the ground gets more solid there is less of lateral and upward 

 pressure, and the sewer becomes subjected to the simple pressure arising from 

 the gravity of the superincumbent material. 



"It appears from the drauing you have produced that one side was more 

 depressed than the other ; will you state the cause of that ? 1 imagine that 

 arose from the sewer being on the side of a hill, and in consequence of the 

 pressure from the hill. The present condition of the sewer is dependent on 

 the circumstance of the earth having becoming stationary. It is not owing 

 to any alteration in the mo le of building the sewer? None wliatever.— Would 

 you still conclude from your experience that the original form was essen- 

 tially bad ? Yes ; 1 consider that the sewer stands now merely from the ac- 

 cident of the ground having become hard and mortar having become consoli- 

 dated. 



Mr. Hugh Biers, an extensive builder, prefers the Finsbury sewers. 

 For a small cheap sewer he proposes the following plan of a sev\er quitesutii- 

 clent for an up[ier drainage to [20 or 30 houses. Do you use any particiil:ir 

 Section of a Sewer for Surface or Upper Drainage. 



At 6 feet depth of digging tliis sewer will cost "s. per foot lineal. For every additional 

 course in deptli add lOd. per foot lineal. 



kind of mortar orcement '^ Stone lime and river sand are always used. — Are 



you satisfied that the nature of the mortar is sufficiently adhesive for those 

 purposes? Yes; quite so, 



What arc the advantages you propose by this new 



form of drain shown in the drawing? Strength and 

 durability with the same inside area as a 12-in. barrel- 

 drain, and without additional cost. — What would be the 

 effect of the discharge of water througli that drain as 

 respects the shape of the bottom ? All tlie sullage must 

 fall to the centre, and the water passing through the 

 drain would by its concentration havc;greatcr jiower in 

 expelling such sullage. 

 You consider an acute angle at the bottom better than the segment of 

 a circle ? I do so ; and the more especially as the segment of a circle in 

 stone would make it very expensive.- I speak from experience ; and where I 

 am not bound by a covenant to construct a barrel-drain, I invariably build 

 one similar to this. In a barrel-drain, a very great portion of the outside is 

 mortar; in this you have nothing but the liard material.— Have you built 

 this drain to any extent? Only to my own private buildings.— What is the 

 actual cost per foot run of a 12-inch barrel-drain ? A 12-inch barrel-drain 

 will cost abiiut 2s. per foot run. — Suppose you had well burnt earthen-pipes 

 sufficiently strong for those communicating drains from the bouse to the 

 larger sewer, which « ould he less expensive and give a sufficient area ? If as 

 durable. I think it would.— Have you seen such? I have seen and used them, 

 especially where there has been a deficiency in the current.— Have you seen 

 them in trial? Yes. I have ; but I do not think they ate so duiable as a 

 brick drain, and there is also a difficulty in taking them up to cleanse.— Do 

 you think for the humbler class of houses some such as those might be adopt- 

 ed ? I think Ihey might, especially if improved upon, and which might be 

 easily done- — Have you any knowledge of those kind of pipes which have 

 been proposed, strong burnt pipes glazed on the inside ? I have not seen any 

 ofa very new construction. — If they were glazed in the inside, would that 

 give a freer waterway than those made of brick', which are of course rough 

 on the inside ? They would of course be much fetter ; and if every third or 

 fourth « as made to open, or be made in halves, or with a cover even less than 

 that, it would be a great improvement in getting at the drain to cleanse it. 

 I have very often constructed drains to the smaller houses, according to 

 this drawing, with a tile bottom, bricks on the sides, and covered with a stone 

 or brick, and I find that much better than the 'J-inch barrel-drain, which 

 requires so much mortar to fill up Ihe outside of the joinls, and besides being 

 so much cheaper— On what do you lay the tile ? On the earth itself, and 



Section of a Drain equal in Area to a 9-incli Barrel Drain, but much cheaper in construe 

 tion, adajiled to the smaller description of houses. 



ZL 



Cost price, lOd. per foot ; the bottom, a strong garden-drain tile, 

 the brick side, just clear of Ihe tile. — Is not there a bad joint ? No;ifitis 

 flushed in with a little cement it makes a much stronger description of drain 

 than the 9-inch barrel-drain. — If they were made of tiles well burnt, and 

 glazed inside, would they not give a freer » aterway than those made of bricks ? 

 Yes. — They would in consequence require less declivity than if made of bricks? 

 Generally speaking, pipes are used where ue cannot get so much current. — 

 That would give you an opportunity of having them shallower ? Yes ; there 

 would not be so much digging.— That would be of advantage, in giving you 

 a clear waterway ? Yes ; where I can get a current I never hesitate about 

 the expense ofa little digging." 



Mr. Roe details the effect of his improvements in the Finsbury commission 

 of sewers. The sewers, at the time he became surveyor, were constructed with 

 upright side walls. The sewer called the first-sized sewer had 14-inch side 

 walls, was five feet in height, and three feet in width ; the second-sized sewer 

 was four feet six in height, and two feet six in width. Soon after he became 

 surveyor a sewer of the first size, with 14-inch side walls, was built in a clay 

 ground at the side ofa hill, by a very good bricklayer, and a very respectable 

 contractor; but, though that had every advantage of execution and material, 

 the side walls, being upright, were not sufficiently strong ; the ground forced 

 in the upper side wall of the sewer for a length of 300 feet. After that, he 

 proposed to the commissioners that they should adopt a curved side wall, 

 instead of an upright side wall. The bottoms of the old drains were semicir- 

 cular. He used the common stock brick for the sides. At the same time he 

 suggested to the coinmissiuners, that by adopting curved side walls it woul 

 do away with four inches of the 14-inch side walls, which would yet Le 

 stringer than before. The commissioners considering that an advantage 



