[94] _Vide_ Mr. Haywood’s Report upon Asphalte and Wood Pavements, also Report on the Application of Science and Art to Street Paving and Cleansing of the Metropolis,’ and numerous other pamphlets and reports by eminent authorities upon the subject. [95] _Vide_ ‘Asphalte and its Application to Street Paving,’ by E. B. Ellice Clarke, ‘Proceedings of the Association of Municipal and Sanitary Engineers,’ vol. vi. p. 52. [96] The asphaltic roadways of Paris, of which there were 290,000 square yards in the year 1878, cost from 10_s._ to 12_s._ per square yard to lay, and about 8·83 pence per square yard per annum to maintain, including the charge for renewing ¹⁄₁₅th part of the surface every year, which is the method adopted there. _Vide_ ‘Annales Industrielles,’ 1878. [97] _Vide_ Mr. Haywood’s report on asphalte and wood pavements, 1874. [98] “Lime concrete ruins compressed work.” _Vide_ ‘Asphalte and its Application to Street Paving,’ by B. Ellice Clarke. ‘Proceedings of the Association of Municipal and Sanitary Engineers and Surveyors,’ vol. vi. p. 46. [99] See p. 94 _ante_. [100] It must be ²⁄₅ths more in thickness than that specified as finished. CHAPTER XI. FOOTPATHS. As in the case of roadways, so with footpaths: the foundation is of primary importance, whatever material may be used for the surface. Where this material may be classed under the head of “Paving,” concrete[101] makes the best foundation. For gravel, tar paving, or other similar surface, a hard core bottom well drained is sufficient. The materials of which a footpath can be formed are almost innumerable, but the following may be given as embodying most of them: (1.) Natural asphalte, compressed and mastic. (2.) Yorkshire flagging--Caithness flagging. (3.) Blue lias, and Devonian limestone flagging. (4.) Concrete. (5.) Bricks. (6.) Granite slabs. (7.) Artificial asphaltes, including tar pavement. (8.) Gravel. First on the list stands natural asphalte, compressed and mastic. The compressed has been thoroughly described in the preceding chapter; it is sometimes used for footpaths where there is a very heavy traffic, and answers admirably. I will, however, now deal solely with mastic asphalte, which means the rock ground to powder, mixed with a certain proportion of bitumen to act as a flux, and then subjected to heat; this is sometimes used in conjunction with fine sharp clean river sand, but more often with finely crushed stone about the size of peppercorns, and is styled “gritted asphalte.” As long ago as the year 1838, Mr. F. W. Simms speaks of asphalte mastic from Pyrimont, near Seyssel, and says “it may be considered a species of mineral leather”[102]--a very good description of its surprisingly tough, hard, durable and pliant properties. The usual method of the preparation of the mastic is as follows:--