1843.] and Hydraulic works in India. 541 



tensive, a number of cauldrons should be heated at once, as one of the 

 indicated dimensions will not lay down more than 70 supl. feet.* 



In laying it down, a lath of the required thickness of the coating is 

 placed across the floor or roof prepared as above, which from the wall 

 or curb, as the case may be, should divide the whole space into com- 

 partments of about 2/6 wide. It is necessary before laying down the 

 mass to cut a small channel (if for a floor under the wall, if for a ter- 

 race close to the curb) of 2 ins. wide and 1 deep, into which hot mastic 

 should be poured, and taken up again when settled in order to warm, 

 and enable the whole to bind and adhere at the edges. Into the com- 

 partments above-mentioned the mastic is poured with a large ladle, the 

 bowl of which should be a foot in diameter and 6 inches deep, each 

 ladleful, as it is poured in, is rubbed from the centre towards the wall 

 or curb with a wooden float (made of cask staves), and a smoothing rod 

 of 3 feet long and 2 feet square is applied to level the surface by a man 

 immediately in rear of the one who uses the float, who also whilst the 

 substance is still hot sprinkles a powder on the surface through a very 

 fine sieve, composed of the finest sand and unslaked lime, reduced into 

 an impalpable powder in equal quantities, which is rubbed in with a flat 

 board, and gives a white surface to the terrace which does not wear off. 

 The surplus is carried forward with such a hand brush as the figure 

 shews, at C as soon as the liquid material is smoothed. Care should 

 be taken to force the substance well into edges and joints, and in remov- 

 ing the gauge rod not to lift it, as it may raise the asphalte with it ; 

 but by a gentle tap to loosen it horizontally from the mass. In laying 

 down at two different times, when the first layer has had time to harden, 

 the edge must be warmed with a little hot material laid on for a mi- 

 nute and removed, the work then to be proceeded with directly. If a 

 roof is covered with wood, coarse canvas should be stretched over it and 

 nailed, and the mastic laid on that, finishing it off with a fillet, as in D 

 of the plate. Store rooms and magazine floors should be 3/4 inch thick, 

 stables 4/8, and carriage drives 1 , coverings of arches 3/8. 



* The cauldron must not be left standing, as the material will burn. 



