616 



PRACTICE OF AGRICULTURE. 



Paut III. 



carriage roads cross the railways; and, at turnings of the railways, great care is required 

 to make them perfectly easy. The rails of the side forming the inner part of the curve 



should be fixed a little lower than the other; and the rails should be set a little under 

 the gauge, so as to bring the sides nearer together than in the straight parts: these 

 deviations in level and width to be in proportion to the sharpness of the curve. The 

 blocks and rails being fixed and spiked last, nothing more remains to he done than to fill 

 the horse-path, or Bpace between the blocks, with good gravel, or other proper materials; 

 a little of which must also lie put on the outside of the blocks, to keep them in their proper 

 places. Tiiis gravel should always be kept below the surface of the rails on which the 

 wheels are to run, to keep the tracks of the wheels free from dirt and obstructions. The 

 form of the tails must be such as will free them from dirt if the gravelling is kept below 

 their level. 



S797. Thejbrmation of edge railways, on the middle or sides of public roads, has been re- 

 commended h\ Dr. Anderson, Fulton, Edgeworth, Middleton, Stevenson, Mathews, Baird, 

 and others. A flat railway, with the rail ten or twelve inches broad, we conceive, might be 

 laid down along the sides of a road with advantage. It would require a rib below of sufficient 

 strength to bear waggons of any weight. This strength would be communicated partly 

 by the mass of material, but chiefly by the rib (/(';,'. 574. a, a), resting on a bed of bricks 

 or masonry below t b). Such a railroad might be used by any description of carriage, 



574 



'" . . .. / . 



light or heavy. But the best description of railroad for the sides of a highway is pro- 

 bably some of those formed of blocks of stone, already described. Stone railways of this 

 sort appear to have been suggested by Le Large (Machines Approuvies, vol. iii.) in 

 France ; and afterwards by Mathews (Committee Examinations, May 1808.) in England, 

 but they have never been fairly tried. The best specimen we have seen is in a street in 

 Milan, where it is not so necessary, the whole breadth being very well paved. 



Chap. V. 



Formation of Canals* 



3798. Though the subject of canals is not included in that of agriculture, yet it is so 

 intimately connected with territorial improvement, that it would be improper in a work 

 of this description to pass it over. Canals of any extent are never the work of an indi- 

 vidual; they are always formed by public bodies, constituted and empowered by public 

 acts : but it is of importance to individuals to know the sort of effect which a canal 

 passing through their property may have, both on its appearance and value ; not merely 

 as a medium of conveyance, but as a source of population, of water for irrigation or 

 mills, or the use of stock, and even as an object of ornament. For this purpose we 

 shall submit some remarks on the utility of canals, the choice of lines, the powers 

 granted to canal companies, and the mode of execution. 



Sect. I. Utility and Rise of Navigable Canals. 



3799. Good roads, canals, and navigable rivers, Dr. Smith observes (Wealth of Nations, 

 i. 229.), by diminishing the expense of carriage, put the remote parts of the country 

 more nearly upon a level with those in the neighbourhood of large towns; and on that 

 account they are the greatest of all improvements. They encourage the cultivation of the 

 remote parts, which must always be the most extensive circle of the country. They are 

 advantageous to towns, by breaking down the monopoly of the country in its neighbour- 

 hood ; and they are advantageous to all parts of the country, for though they introduce 

 some rival commodities into the old markets, they open many new markets to its produce. 

 " All canals," says an intelligent writer on this subject (See Phillips's General History cf 

 Inland Navigation, Introd. ), " may be considered as so many roads of a certain kind, on 

 which one horse will draw as much as thirty horses on ordinary turnpike roads, or on 

 which one man alone will transport as many goods as three men and eighteen horses 

 usually do on common roads The public would be great gainers were they to lay out 

 upon the making of every mile of a canal twenty times as much as they expend upon 

 a mile of turnpike road ; but a mile of canal is often made at a less expense than 



