A sample of the footpath after it is laid should be cut out (this is easily effected by heating the surface with a piece of hot mastic), in order to see that the proper thickness is given, and by applying a light to the sample, the smell will readily tell if real asphalte or any inferior material has been used. Stockholm tar or common pitch should not be allowed to be substituted for Trinidad bitumen, or it will spoil the mastic. Asphalte mastic footpaths are excellent in every way, the only objections to them being the necessity for the grit, and the temporary unpleasant smoke and smell whilst being laid. It is also necessary to put stone sills round the cellar openings and coal shutes, etc., for it to butt against, but it makes an invaluable pavement, especially for courts, alleys, back yards, etc., for sanitary and other reasons. The proportions of asphalte, bitumen and grit are given as follows by Mr. Delano in his translation of a paper by M. Ernest Chabrier, on the applications of asphalte.[104] “One ton of sanded mastic requires 13 cwt. of pure block mastic, 2 qrs. 12 lb. of bitumen, 7 cwt. of grit or sand washed and dried,” and it takes 2 cwt. of coal to heat it. He further says that one workman can easily prepare 3 tons of material in 12 hours. The following table gives the number of square yards that a ton of prepared Sicilian rock asphalte will spread. ----+--------------+---------------------+----------+---- | | With about | | |Without grit. |25 per cent. of grit.|Thickness.| +--------------+---------------------+----------+ |square yards. | square yards. | inches. | | 63 | 80 | ³⁄₈ | | 51 | 65 | ¹⁄₂ | | 32 | 40 | ³⁄₄ | | 26 | 33 | 1 | | 16 | 20 | 1¹⁄₂ | | 12¹⁄₂ | 16 | 2 | ----+--------------+---------------------+----------+---- A skilled workman properly assisted can lay 140 to 180 square yards in a day.[105] With regard to the price of asphalte mastic footpaths, this is quite a local question, and is not worth while discussing. The life of a footpath thus treated may be reckoned at about 15 years under ordinary traffic; the concrete will remain untouched and what is left of the asphalte may be remelted, so that a renewal is not so costly as the first expense. _Yorkshire Flagging._--This pavement is too well known to need any description from me; it is an excellent pavement in many ways, and is most pleasant to walk upon, there being a cling or foothold not experienced in any other material. The objections to this description of pavement are:-- (1.) Its first cost, which is undoubtedly high as compared to its durability.