1 848. 1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



279 



do not give satisfaction. From the misconduct of the Ordnance 

 functionaries, the corporation of Liverpool are put to the trouble, 

 expense, and delay of a second survey — and, to make it worse, they 

 have no remedy. Whetlier the metropolitan survey will turn out 

 better we have our doubts : but it remains to be seen. At all events, 

 the Treasury will have to make good any short-comings of the 

 Ordnance surveyors. 



If the Ordnance have been unable to do their work properly and 

 in time at Liverpool, what security have we against delay in the 

 general and metropolitan surveys .-" To the great disgrace of 

 the government, engineers have long had to use the northern 

 sheets of Mr. C'ary's survey ; and now this dilatory body, having 

 proved itself incompetent in its past duties, is to have more thrust 

 upon it. Why do not the Associated Surveyors get Mr. Wyld to 

 move for a parliamentary committee of inquiry into the general 

 management of the surveys carried on by the Ordnance ? 



This Report is a sufficient specimen to show that civil engineers 

 are not incompetent for sanitary duties, and we hope it will not be 

 forgotten, for doubtless Mr. Chadwick will next propose that 

 mUitary engineers should be chosen to lay down the lines of drain- 

 age, and carry out the details under the " Health of Towns" Act. 



The Report may be divided into the following parts : — 



Sewage and drainage, what are the necessary conditions to pro- 

 duce a perfect system. 



Description of the borough of Liverpool in relation to the river 

 Mersey and the docks — the effects of discharging the sewage into 

 the docks and river. 



Schemes for constructing a new sewage. 



Lists of all the existing sewers, showing their size and length — of 

 new sewers required. 



Estimates for forming the new system of sewage. 



On the a])plication of the sewage water for fertilizing the soil. 



On the form and size of sewers and drains. From this part of the 

 report we make the following e.xtracts : — 



Sewers and Drains. — The proper size and forms of sewers and drains is a 

 Eubject which of late has excited much controversy. In so far as the honse 

 drainage is concerned, the question lies within narrow limits; for if all the 

 liquid refuse of a house passes through a soil-pipe of 2^5 or 3 inches diameter, 

 there is surely no need of the drain which receives it being made much 

 larger. ]f more than one pipe enters a drain, the question is still a simple 

 one; and although, by calculation, the corresponding increase of capacity 

 for every adilitional pipe which enters the drain could be readily determined, 

 practice will hardly admit of the refinement which would so nicely adjust 

 the increments ; and it Is easy so to proportion the drain pipe in each case 

 with the materials in practice at our disposal, that it shall be no larger than 

 the quantity of water avadable under the particular circumstances of the 

 case shall thoroughly flash. Pipes of from three to sis inches internal dia- 

 meter, are amply sufBcient for service drains, as one of &ix inches, with a fall 

 at the rate of one in forty will, according to the ordinary formula, discharge, 

 in half-a-minute, as much water as is due to a family of six indiTiduals for a 

 whole day, even on the liberal scale of five cubic feet per head. 



a, Carriage Pavement ; i, Channel Stone; c, Curli ; </, Foot-Paving; 

 e, Coal-Vault Shoot ; /, Gas-Pipe ; ji, Water-Pipe; A, Sewer; 

 i. Syphon Trap; j, Tube; k, Coal-Vault. 



The drains of streets should, in my opinion, be double in all the streets 

 above twelve yards wide ; and in such cases I would construct them in the 



bottom of the side trenches for the water and gas pipes, as shown in the 

 annexed engraving. By this arrangement are insured diminished capacity 

 and direct communication, and the other advantages connected with the 

 paving, elsewhere insisted on. The first cost of the double sewer is nearly 

 balanced by the saving in the service drains ; and in regard to the paving, it 

 is impossible sufficiently to estimate the saving, if, in connection wilb these 

 side trenches, the more durable manner of paving recommended be intro- 

 duced. The sewer proposed to be used in this case consists of a semi-oval 

 nuderpart, formed of stone ware, or some of the other materials which will 

 afterwards be noticed, and a semicircular cover, as shown in the above 

 engraving. The joinings I propose to form with the pitch of coal-tar, in 

 rather a soft state ; and when any part of the drain requires to be in- 

 spected, a hot iron or a little blazing straw will soften the cement so much 

 as to admit of the cover being removed. Service drains are connected 

 with the side drains by means of sockets formed in the latter. 



The report proceeds to denote the different forms of sewers and 

 their connections, which are something similar to those described 

 in the Journal for March last, p. 77. It then gives the area of land 

 drained into each of the main sewers. 



From observations made while Beacon's Gutter sewer (6ft . by 4 ft. 6 in.) 

 was opened at its outlet, for the admission of the new sewer in Great How- 

 ard-street, it was found that the water was only 20J inches deep, after 

 twelve hours of heavy rain. 



The extent of drainage into that sewer is 983-3 acres ; of which about 

 one-fourth is built, and three-fourtbs unbuilt. Now, by the formula most 

 approved, the diameter of sewer necessary for this drainage, with the given 

 fall, would be ten feet, while the actual diameter of the sewer at its largest 

 part is only 4 ft. 6 in., and the depth of water in it was somewhat less than 

 a third of its longest axis, even after the continuance of heavy rain for 

 twelve hours, when it may be reasonably supposed the whole earth would be 

 saturated, and every drop of rain would flow into the sewer. AH calcula- 

 tions for the capacity of sewers proceed on the assumption, that it is neces- 

 sary to provide for the contingency of a rain flood, estimated at the enor- 

 mous fall of five-eighths of an inch in half-an-hour. Now, that such a flood 

 may occur is possible ; but it would be easy to show, that if it did occur, it 

 could not get into the sewer, and therefore there is no necessity to make 

 provision for it ; and it requires merely a glance at the streets of a town 

 built on sloping ground like Liverpool, during even a moderately heavy rain, 

 to be convinced, that a great part of the rain drains directly by the surface 

 of the street into the river, and never enters the sewers. As all formulre 

 then, are founded on imperfect experiments, and give results so far above 

 what experience shows to he necessary, they are obviously uncertain guides, 

 and it is belter to trust to the observations of what actually takes place. 

 This, in fact, is experimenting on the largest and most proper scale. 



The Report afterwards makes some observations on surface drain- 

 age and paving. If the streets of a town he unevenly paved, putrid 

 exhalations will constantly arise. A smooth, non-absorbent, hard 

 surface, without hollows or joints, is what health demands. Mac- 

 adamised streets are the worst : the absorbent material soaks up the 

 liquid filth, v^hich, putrifying, sends its noxious exhalations into the 

 atmosphere ; and the road wears fast under great traffic — in wet 

 weather it is covered with mud, and in dry weather the air is loaded 

 with dust. It is the most expensive to keep in repair, and costs 

 four times as much to cleanse as a paved road. Boulder paving is 

 the next lowest in the scale of roads. Streets formed witli stones 

 dressed in regular courses are the best : where the road is steep the 

 courses should be of stone 3 inches wide, with joints l| inch 

 wide, filled up with cementitious substance, impervious to water. 

 In streets less steep, the stones may be increased and the joints 

 decreased. On a level, the stones may be increased to 5 inches in 

 vi'idth. 



To insure stability, the courses should be made nearly wedge-form. They 

 should be in contact at their base and for about one-third of their height, 

 and the width of the joint should be obtained by diminishing the width of 

 the upper surface of the courses. The joints should be rammed hard wllh 

 macadam or clean shingle, and then filled with a coarse kind of asphalte, 

 composed of the jiitch of gas-tar and small gravel. The joint should not be 

 filled quite flush v»ith the surface of the stones, but left slightly hollow, as in 

 the figure (a). If the expense of the asphalte be objected to, lime grout may 

 be used to fill the joints. The lime should, for this purpose, be such as 

 will set under water. 



For the foot-pavement, Caithness stone, l| inch thick, with 

 sawn joints, is recommended in preference to Yorkshire stone 3 

 inches thick. 



A good foundation to a road is no less essential than a good surface ; 

 hardness in the latter cannot be insured without firmness in the former. 

 Softness or elasticity in a foundation will permit the surface to yield under 

 the wheels of a carriage. The rise and fall forms a new obstacle to be over- 

 come, and causes an increased amount of friction to be opposed to the 

 moving power. Besides, by the sinking of the paving material, the soft 

 earth is forced up between the stones, and covers the road with mud. It is 

 worth while, then, to be at a little extra cost in the preparation of the 



