Note 53 — Chapter VIII · PITCHED PAVEMENTS.

Birmingham in 1854 had not, I believe, a single mile of paved streets; the principal ones are now nearly all paved with granite setts, and over 20,000 square yards were so paved in 1880.

[54] It is said that the cost per annum per square yard of granite paved roadways is but 3d., whereas the same cost for macadamised roadways under the same circumstances is 1s. 6d.

[55] In Paris after considerable research into the question, the engineers of the Ponts et Chausseés, decided that the size of the paving stones, which used formerly to be 9 inches square should be 4 inches wide by 6¹⁄₄ inches long by 6¹⁄₄ inches deep, the stone that is used being a grit sandstone, from the forest of Fontainebleu.

[56] Vide ‘Minutes of Proceedings of the Institution of Civil Engineers,’ vol. lviii. p. 66.

[57] Syenite is a hard, greenish-grey metamorphic rock, composed principally of silica, alumina, and lime, in conjunction with magnesia, iron, etc. Its specific gravity is 2·96.

[58] Mr. Boyle, District Surveyor of Manchester, says: “I would caution you against the use of the old blue Penmaenmawr stone as being an extremely slippery stone, and one which makes a dangerous pavement.” Vide ‘Proceedings of the Association of Municipal and Sanitary Engineers,’ vol. iii. p. 58.

[59] The old granite paving of London used only to last eight years. Vide ‘Minutes of Proceedings of the Institution of Civil Engineers,’ vol. ix. p. 222.

[60] Vide ‘Street Carriageway Pavements,’ by George Frederick Deacon, M. Inst. C.E., ‘Minutes of Proceedings of the Institution of Civil Engineers,’ vol. lviii. p. 1 et seq.

[61] The pavior’s rammer is about 55 lb. in weight, with an iron ring at its foot; this is swung with some dexterity between the legs, and is allowed to fall with great force upon the earth or stones it is in use upon.

[62] The usual specifications for the Guidet paving blocks (in New York) require that they shall be of granite, equal in hardness to the Quincy granite, of durable and uniform quality, each measuring not less than 3¹⁄₂ nor more than 4¹⁄₂ inches in width on the upper surface or face, and not less than 10 nor more than 15 inches in length, and not less than 8 nor more than 9 inches in depth. Blocks of 3¹⁄₂ inches in width on the face to be not less than 3 inches in width at the base; all other blocks to measure on the base not more than 1 inch less in width or in length than on the face. The blocks are set upright in close contact on their edges in courses, with the longest dimensions and the continuous joints running across the street, breaking joints lengthwise of the street.

The ends of the blocks are dressed off so as to give close joints in the direction of the draught, while the broad vertical sides of the blocks are left rugged or uneven, or with the split rock-face so that the continuous joints running across the street are somewhat open. Vide ‘Roads, Streets, and Pavements’ by Q. A. Gillmore, p. 157.

[63] Vide ‘A Treatise on Roads,’ by Sir Henry Parnell, p. 130.

[64] As these ingredients often vary very much in their constitution, the surveyor must use his judgment to a great extent as to these proportions.

[65] These boilers are now much used for such purposes, they hold from 60 to 500 gallons and are light and portable; the temper of the bituminous mixture also remains uniform whilst being drawn off, and there is very little evaporation or waste arising from them.

[66] Since writing the above, the Liverpool and Manchester tram-road was designed I believe on this principle.