3191. Is there anything more in connection with that plan which you wish to mention?--- I think not ; except that the gradient on this southern loop is 1 in 50 up and down.
3192. Sir Philip Nash : The bottom section is H to J, is it not! --- Yes ; and this is from J to K.
3193. Mr. W. H. Gattie : Turn now to your eastern tubes! --- These section for the eastern tube is not quite finished.
This is the preliminary draft. (Producing section.) This is the approximate line I have adopted, 1 in 50 down, then 1 in
1000---- practically level --- to a point here, where it rises to 1 in 60 in Bishopsgate Goods Yard.
3194. With regard to that tube, have you what you described as balanced grades? --- Yes.
3195. What do you mean by that? --- A balanced grade is where you have the following a down grade an up grade. A well balanced grade is where you get the two heights corresponding in some degree approximately to the same level.
3196. What is the minimum radius of the eastern tube? --- About 400 feet.
3197. Have you gone fully into the question of the obstructions that you are going to meet with in building these tubes? I believe you have come to the conclusion that you must cut into two sewers? --- Yes.
3198. Which tubes are they? --- There are only two places where we interfere with pipes, leaving out the space occupied by the Clearing House, of course, that is there and there ; and it is not possible to get past those two points without syphoning a 10 feet barrel sewer here, which becomes, I think, 9 feet 6 inches. below at this point, and also 4 by 6 by 2 feet, 8 inches., which runs alongside it. There is no other place where we shall interfere with pipes, except that there may be one or two of quite small dimensions, which are hardly worth considering.
3199. I think the Committee would like you to identity by z mark where you propose to cut into those sewers? --- zI will call them X and Y.
3200. I believe it is quite common to Syphon sewers under those conditions, is not it --- I mean it can be done? --- It can be done. It is not always done; it is not often necessary, but it was necessary here where the Metropolitan Railway had to Syphon the Fleet River sewer, that is s somewhat larger pipe than this, actually 10 feet 6 inches., I believe.
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