232 BOARD OF AGRICULTURE. [Pub. Doc. 



maker is next to secure it from rain-water, by a solid road 

 made of clean dry stone or flint, so .selected, prepared and 

 laid, as to be perfectly impervious to water ; and this can- 

 not be effected unless the greatest care be taken that no 

 earth, clay, chalk or other matter that will hold or conduct 

 water, be mixed with the broken stone, which must be so 

 prepared and laid as to unite with its own angles into a firm, 

 compact, impenetrable body." 



Find room for a " porous" spot in that, if you can. 



In the accounts of the road-trusts he overhauled, M'Adam 

 saw well enough how figures could be made to lie, and so 

 preferred to avoid giving mathematical color to suspicion in 

 his writings ; yet his meaning is plain. He had unbounded 

 faith in wrought stone over dry earth. But who has seen 

 his ideas exemplified in any quarter of the world? Let him 

 repeat : — 



" The thickness of such [stone] road is immaterial as to 

 its strength for carrying weight; this object is already 

 obtained by providing a dry surface over which the [stone] 

 road is to be placed as a covering or roof, to preserve it in 

 that state; experience having shown that, if water passes 

 through a road and fills the native soil, the [stone] road, 

 whatever may be its thickness, loses its support and goes to 

 pieces." 



"Encyclopedia Britannica," while admitting "road-scrap- 

 ings " among " binding material," declares that " The name 

 M'Adam often characterizes roads on which all his precepts 

 are disregarded.'''' 



That broken-stone road may be a " roof," shedding water 

 from its own foundations, as well as a "smooth floor," 

 affording pleasant wheeling at all seasons, were among 

 M' Adam's principles and practices, and are what we want 

 to-day; but we can reach no such result as that in the way 

 of porous, crumbling bottom-work, a ventilated mid-struc- 

 ture, and the diip-stone which should fill its crevices reserved 

 for top-dressing. 



Our modern way of screening and assorting road metals 

 — so abundantly illustrated in rock-crusher circulars — has 

 left our roads open at the top to water and tilth, open at the 

 bottom to clav, and open everywhere to the question 



