BooKir. PRESERVATION AND REPAIR OF ROADS. 607 



3738. J. Farey is of opinion that varying the length of axles, so as to prevent their 

 running in the same track, w^ould be very beneficial. This he particularly stated to the 

 Board of Agriculture, with an example of the tolls over a new road in Derbyshire, 

 which are regulated according to the length of the axle. 



3739. The division of weight has been proposed by Fry as a means of preserving roads : 

 that is to say, the division of the power, which any carriage may possess, to crush or 

 destroy the materials of the roads ; and the division of the power, which any carriage 

 may possess, to resist the power of the horses drawing such carriage. " A man can break 

 an ordinary stick, an inch in diameter, across his knee ; but if he tied ten of these sticks 

 together, he could not break them if he tried ten times, nor if he tried a thousand times ; 

 although, by these thousand efforts, he might have broken a thousand such sticks sepa- 

 rately. A stone might be of such a size and texture that a strong man with a large 

 hammer might break it into pieces at one blow ; while a boy with a small hammer, 

 striking it with one tenth part of the force, might strike it a thousand times, applying in 

 the whole one hundred times the power upon it that the man would have done, without 

 producing the same effect. So it is with the pressure of wheels on the materials of the 

 roads. Suppose a stone, the size of a man's fist, to be detached on a firm part of the 

 road, and a waggon-wheel, pressing with the weight of two tons, were to pass over it, 

 the consequence would be that it would crush it to powder. But suppose these two 

 tons to be distributed into forty wheelbarrows, of one hundred weight each, and they 

 were to pass over over it succession, the only effect likely to be produced would be a 

 trifling rounding of its corners ; nor would probably five hundred such wheelbarrows, 

 of twenty-five tons, crush the stone so completely as the single waggon-wheel. Nor do I 

 think that five hundred gig or one-horse chaise wheels, of four hundred weight each, in 

 all one hundred tons, would so completely destroy the cohesion of the stone, as the single 

 crush of the heavy wheel. Conceiving, therefore, that the destructive effect of pressure 

 on the roads increases, from the lowest weights to the highest, in a very rapidly increasing 

 ratio, I think that all reasonable ingenuity should be exercised, so to construct our car- 

 riages, as for each wheel to press the road with the least possible weight that the public 

 convenience will allow." 



3740. A great weight in one rolling mass {Jig. 564.), Fry continues, " has a tendency 



to disturb the entire bed of the road, whether it be on a six-inch wheel or on one of 

 sixteen inches, and whether on conical {Jig. 563. a) or on cylindrical wheels {Jig. 563. b). 

 Under all these considerations, I am satisfied that the only grand desideratum, on behalf 

 both of the roads and the horses, is light pressure; and therefore any dependence 

 on breadth of wheels, as a security against the destructive effects of pressure, is in 

 my opinion fallacious. I wish here to be understood as applying these remarks upon a 

 supposition that wheels were made upon the most philosophical construction ; that is to 

 say, perfectly cylindrical {Jig. 563. b) ; and that they stood perfectly upright or vertical. 

 The present system of broad wheels I consider a system of mere mockery." 



3741. Frt/ proposes to attain his principle of the division of power by the adoption of light one-horse 

 waggons with six or eight wheels ; which in our opinion are of very questionable advantage, all things 

 considered, compared to one-horse carts, to carry one ton, and four-wheel waggons to carry four tons. 

 " One-horse waggons " he says, " fully embrace the principle; and the labour of the horses would be 

 much more efficiently applied than at present. If light one-horse waggons were constructed, to weigh 

 eight hundred weight each, and these were charged with a load of sixteen hundred weight each, a good 

 ordinary cart-horse would travel England over with such a load ; drawing just as much net weight as the 

 ten horses in a heavy waggon take each in gross weight ; and the roads would never have a pressure, on 

 one point, exceeding six hundred weight. The only objection to such carriages that I see is, that each 

 must be attended by a man. [There is no reason for this ; in Scotland one man always drives two single- 

 horse carts ] But, were they adopted, roads would last, I will not say ten times as long, I think they 

 would last a hundred times as long, as they now do. Carriages so constructed ought therefore to pass at 

 the lowest possible rate of toll. The next mode is by the use of carriages with six or eight wheels. About 

 twenty years ago there were several stage-coaches constructed in this manner. Two eight-wheel coaches 

 plied some years between Bath and Bristol ; and they were so constructed that each wheel supported 

 its share of the load, carrying its proportion, and no more, over every obstruction : the consequence was, 

 that when a wheel passed over a stone two inches high, the middle part of the carriage rising only an 

 eighth part of two inches, or one quarter of an inch, they were perhaps the easiest coaches to passengers 

 that ever were sat in. They had, however, one defect in their construction ; which was, that the two 

 hinder axles being fixed, whenever the coach varied from a straight line on the road, the hindermost pair 

 of wheels must have been dragged sideways. How the six-wheel coaches were circumstanced in this 

 respect, I had no opportunity of observing." 



