14 Mr Stevenson on the Building Materials 



thin pieces called " shingles," while the spires of the churches, 

 which rise from all the principal towns on the banks of the 

 St Lawrence, are covered with highly polished tin. 



Another of the many illustrations that may be given, ap- 

 pears in the construction of roads — a most important branch 

 of engineering. The roads in this country are now invariably 

 Macadamized, as materials hard enough for forming them ad- 

 vantageously on that principle are very generally met with 

 throughout the length and breadth of the island. In France, 

 on the other hand, the want of hard materials renders Maca- 

 damizing not so applicable ; and consequently, it has not by 

 any means been generally introduced in that country, many 

 of the principal roads being still pitched or paved with large 

 stones. In Holland, owing to the scarcity of "Stones of every 

 description, most of the roads are paved with small well- 

 burned bricks, called " clinkers," which are set in sand, and 

 present an exceedingly smooth surface ; while in America and 

 Russia, we find long stretches of " corduroy road, " con- 

 structed entirely of timber — the produce of their extensive 

 forests, which forms a species of highway by no means so well 

 calculated as any of the others alluded to, for extending com- 

 munication or promoting the comfort of the traveller ; as the 

 painful experience of every one who has travelled on them 

 can abundantly testify. 



The materials of every country may therefore be regarded 

 as a subject of great interest connected with its history, and 

 this consideration has induced me to offer a few remarks on 

 the materials employed in the construction of the public works 

 of the United States, in, the belief that they may not be un- 

 interesting to the members of a society which has for its ob- 

 ject the promotion of the useful arts. 



Iron is pretty abundant in North America, and it is worked 

 in several parts of the United States. The only iron-works 

 which I had an opportunity of visiting in the course of a 

 late tour in that country, were those in the neighbourhood 

 of Pittsburg, on the river Ohio, which are said to be the 

 most extensive in America. At this place, the workmen 

 were engaged in the manufacture of pig-iron and plate-rails 

 for railroads. The use of plate-rails, howevei', has been very 



