600 PRACTICE OF AGRICULTURE. Part III, 



Guernsey or other pebbles, or water-worn granitic or trapstones. Walker prefers the 

 granite of Guernsey to that of Aberdeen. 



3709. The size of the st07ies used in road pavements is commonly from five to seven 

 inches long, from four to six inches broad, and from six to eight inches deep. Walker 

 prefers stones nine inches deep ; and Telford is of opinion that the general shape of the 

 stones at present used for paving, and the mode of distributing them, are very imperfect ; 

 the lower part of the stones being of a triangular wedge-like shape, which, instead of 

 enabling them to resist the weights which come upon them, easily penetrate into the 

 substratum : the stones are also broken of an unequal size. The remedies for these 

 defects are obvious : they should be as nearly as possible of a cubical form, the lower bed 

 having an equal surface with the upper face ; they should be selected as nearly as possible 

 of an equal size, and they should never be of unequal length on the face. In quarrying 

 and preparing the stones there would certainly be an additional expense in the prepara- 

 tion, because there would be more work required in the dressing, and many stones 

 must be rejected which are now used ; but the additional expense would be very well 

 bestowed. 



S710. In laying down the stones, each stone, according to Edgeworth, should bear 

 broadly and firmly on its base ; and the whole should be rammed repeatedly, to make the 

 joints close ; the upper and lower sides of the stones should be as near each other as pos- 

 sible, but they should not touch each other laterally, except near the top and bottom, 

 leaving a hollow in the middle of their depth, to receive gravel, which will serve to hold 

 them together. This method of paving may be easily executed by common workmen, 

 who may throw in gravel between the stones as they are laid down. It may be easily 

 conceived, that if a grain of gravel inserts into holes that are in stones opposite to each 

 other, it will dowel them together. It will be useful to cover a newly made pavement 

 with gravel, which will preserve the fresh pavement for some time from the irregular 

 pressure of wheels, till the whole is consolidated. The stones should be of equal hard- 

 ness, or the soft ones will be worn down into hollows. In every species of paving, 

 no stones should be left higher or lower than the rest ; for a wheel descending from 

 a higher stone will, by repeated blows, sink or break the lower stone upon which 

 it falls. 



8711. T/ie requisites for laying down the stones and forming a good pavement are, 

 according to Walker, to have the stones properly squared and shaped, not as wedges, 

 but merely as rectangular prisms; to sort them into classes according to their sizes, so as 

 to prevent unequal sinking, wliich is always the effect of stones, or rows of stones, of 

 unequal sizes being mixed together ; to have a foundation properly consolidated before 

 the road is begun to be paved ; to have the stones laid with a close joint, the courses 

 being kept at right angles from the direction of the sides, and in perfectly straight lines ; 

 the joints carefully broken, that is, so that the joint between two stones in any one course 

 shall not be in a line with or opposite to a joint in any of the two courses adjoining. 

 After the stones are laid they are to be well rammed, and such of the stones as ap- 

 pear to be rammed loose should be taken out and replaced by others; after this the joints 

 are to be filled wdth fine gravel, and, if it can be done conveniently, the stability of the 

 work will be increased by well watering at night the part that has been done during the 

 day, and ramming it over again next morning. The surface of the pavement is then to 

 be covered with an inch or so of fine gravel, that the joints may be always kept full, and 

 that the wheels may not come in contact with the stones while they are at all loose in their 

 places. Attention to these points will very much increase both the smoothness and the 

 durability of the paving. He has found great advantage from filling up, or, as it is 

 called, grouting the joints with lime water, which finds its way into the gravel between 

 and under the stones, and forms the whole into a solid concreted mass. The purpose 

 served by the lime might also be eflectually answered by mixing a little of the borings or 

 chippings of iron, or small scraps of iron hoop, with the gravel used in filling up the 

 joints of the paving. The water would very soon create an oxide of iron, and form the 

 gravel into a species of rock. He has seen a piece of rusty hoop taken from under water, 

 to which the gravel had so connected itself, for four or five inches round the hoop, as 

 not to be separated without a smart below of a hammer ; and the cast-iron pipes which 

 are laid in moist gravel soon exhibit the same tendency. 



37 12. As substitutes for paving stones, plates of cast iron moulded into the form of the 

 surface of a pavement of different sizes {fg. 558. c, d, e) have been tried ; but on the 

 whole they are not considered as likely to succeed. They are very hot in summer, and more 

 slippery than stone in winter ; but what is most against them is, that the water finds its 

 way beneath them and softens the substratum. This, at any time of the year, tends 

 directly to produce holes by the leverage of wheels and the feet of animals (3573.) ; but 

 after a severe frost the effects are ruinous. At all events, this description of pavement 

 does not appear so well adapted for the sides or middle of public roads as that pf granite 

 stones prepared in Telfoid's manner (3700.). 



