Mr. Haywood says,[79] “Wood pavements with repairs have in this City (London) had a life varying from 6 to 19 years, and that with repairs, an average life of about 10 years may be obtained.” The life of wood is no doubt extended by being preserved by one of the processes I have enumerated, but as its life may be taken as an average of 8 to 10 years, and as the blocks are bound to wear unevenly, they should be made as shallow as is consistent with stability; as it is an undisputed fact that the foundation of a roadway is the important carrier of the traffic, the surface material, of whatever it may be constructed, only acting as a skin to preserve it. If the blocks are too thick, unnecessary capital is locked up. Wood pavement was laid in Sunderland[80] in 1859 with strips of creosoted red pine, creosoted beech wood, and unpreserved oak, the bulk of the paving being unpreserved red deal, and this was replaced in 1867. In 1877, on renewing the pavement, it was found that the creosoted wood suffered less from wear and tear than the unpreserved, so the whole was done with creosoted red pine, the original strip of creosoted red pine was left untouched, the strip of oak was turned, and the beech was merely raised; and there is no doubt that the best wood pavement is that which can be constructed in the simplest manner, as for instance deal blocks 4 or 5 inches deep, laid with a close joint upon a Portland cement concrete bed, the blocks being well grouted in with Portland cement grouting, their surface being afterwards sprinkled or strewn with sand or sharp gravel. The woods employed for paving are beech and oak, both of which are said to be too slippery, elm, which is not durable, pitch pine and Baltic fir. Memel and Dantzic timber is better than Riga, the best wood for the purpose being said to be Wyborg or St. Petersburgh red deals. All sappy wood must be at once rejected as unsuitable. This is a great objection to creosoting or other preserving processes, as it hides defects in the wood. The advantages of wood paving may be summed up as follows:-- (1.) It is the quietest of all known pavements, wheels make scarcely any noise upon it and there is no clatter of horses’ hoofs. (2.) It is much safer than either asphalte or granite pavements for horses travelling upon it and if a horse falls he can rise more easily. (3.) The traction necessary upon it, though slightly greater than upon asphalte, is compensated for by the better foothold given to horses. (4.) It is clean. If well constructed there should be no mud made upon it; all that appears upon its surface should arise either from its being imported upon it, or from the gravel with which it is sometimes necessary to dress the surface. (5.) It presents a uniform and slight elasticity, which is of great benefit to vehicles passing over it. (6.) It may be laid on a gradient of 1 in 20 with safety to the traffic. The principal objections to wood as a paving are:--