280 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



LSbpteitoeb, 



fouiiJation, wlien so much depends upon it ; and I think the following plan 

 the best adapted to secure perfect firmness. A level bed is prepared for the 

 laaterials, and on this a paven\ent of common soft rock is laid by hand. The 

 deepest stones are used for the centre, and the size is diminished towards 

 the side, so as to brini; the top line nearly to the intended transverse section 

 of the road. The stones are all laid on their broadest edges lengthways 

 across the road, and the thickness of the upper edp;e should not exceed four 

 inches. When the setting is completed, the irregnlariiies are broken off by 

 hammers, and the interstices filled in vpith the chips. On the foundation so 

 prepared, a three-inch stratum of small broken stones is to be laid, and on 

 this, where the case will afford it, a coating of clean gravel should be spread, 

 and the whole rolled with a heavy roller until consolidated, when it is in a 

 condition to receive the covering of paving stones. The under pavement 

 would be still farther improved by running the joints with good lime grout 

 before laying on the ballasting; anil in the case of macadam roads, the pre- 

 vious ballasting is not required, the macadam being laid directly on the 

 pavement. 



The objection to a street formed and paved in a manner so permanent 

 as that described, is, that it requires to be frequently broken up for laying or 

 repairing water and gas pipes and making branch sewers, and cannot he 

 reinstated in so perfect a manner. But water and gas pipes should not be 

 laid in the carriage way, hut in trenches formed along the sides of the 

 streets, as shown in the foregoing engraving, and the sewers should he double 

 and laid in the bottom of these trenches. The advantages of this mode of 

 forming streets I have before pointed out, and shall now merely exhibit a 

 statement of the comparative cost of the two modes. The calculation is 

 made for a street fifteen yards wide, and the actual cost of both modes is 

 given : — 



Estimated cost of side-trencties for gas and water pipes, and seiaers. 



fi Va^tlg Brickwork, in one lineal yard, at 33. (jd. per yard superficial ,.£110 



1(1 Vards Bricliivork do. do. at33. Od. „ cube .. 10 



Cust I^on Bearers do. do. at.^s. <>i. „ .. .. H 6 



Side Eutrances (every 4'i yards) at Is. 6 J. „ .. ..016 



Total, 



^2 8 



Eitimated saving in the cost of laying down gas and water pipes, and 

 excavating fur sewers by using side-trenches. 



In the Lineal Yard. 

 Main Sewer, 10 yards excav^itiag, say one-half, at la. Od. 

 Gas Pipes do. 2s. 3d. . 



Wul»r Pipes do. 2i. 3d. , 



House Drains do. and Pipes Us. Od, . 



Branch Pipes {Gas and Water) do. 23. 6d. . 



j^O 10 



3 3 



3 3 



9 



2 6 rfl 8 



The diSerence of expense 



ie\ 



The excess of the cost of the trenches is £\ per lineal yard of street ; but 

 to counterbalance that cost, there is the saving in keeping the street in repair 

 and cleansing it — the convenience and the non-interruption of the traffic — 

 and to these it is impossible, in the present state of information, to assign a 

 money value. 



For cleansing streets, the Report recommends washing them with 

 water, and carrying the slush off by the sewers, instead of carting 

 the sweepings ; by which means an enormous saving will be effected. 



The water channels ought to be formed with smooth-faced stones 

 10 inches wide and 6 inches deep, and from 2 to 4 feet long, laid to 

 the general curved line of the cross-section of the street, which 

 can be laid at 6s. 6d, the superficial yard. — (iS'ee 6 in the engraving 

 on previous page.) 



(r'aWy- Graces should all be trapped, and the grating-bars either be so 

 close as not to admit stones and other matters which might impede the flow 

 of water in the drains, or the longitudinal openings may be crossed under- 

 neath by small wires, forming, with the bars, a series of reticulations, which 

 will prevent the passing of any large substance. The kind of trap which 

 experience proves to be efficient is alluded to in the next paragraph. 



All traps which depend on the agency of water, are lialde to get out of 

 repair, and require care and attention to maintaiu their efficiency. For if 

 the water be allowed to dry up, the gases have free passage ; and if it be 

 allowed to remain long in the trap without being changed, it becomes im- 

 pregnated with the gases, and yields them again to the air : constant change 

 of the water is thus essential to the perfect action of such traps. The forms 

 of water traps are very numerous ; but probably the most simple and efficient 

 for house drains, when the drain pipe is not too large, and the supply of 

 water abundant, is the plumber's trap, which is a pipe bent to the sigmoid 

 curve, as in fig. 5. 



Where the quantity of water passing through a pipe is very small, and 

 yet the pipe requires to be large enough for an occasionally-increased dis- 

 charge, some trap, which can be opened to admit of any deposit being 

 cleaned out, is probably to be preferred, and I have hitherto used the one 

 represented at g, fig. 4. This is merely a modification of the former, and 

 answers well. It is made of earthenware. Wliere the fall of a sewer is not 

 great, and the house drains are apt to be filled with back-water, the flap 

 Talve is the most effectual preventive which 1 have tried. It answers ad- 

 mirably for keeping out back-water, and fits so tightly that no gas can escape. 

 These valves can now be had made entirely of earthenware. The gully 



