Book II. CANALS. 617 



the mile of turnpike ; consequently there is a great inducement to multiply the number 

 of canals." 



3800. General arguments in favour of canals are superseded by the rapidly improving and tliriving state 

 of the several cities, towns, and villages, and of the agriculture also, near to most of the canals of the 

 kingdom ; the immense number of mines of coal, iron, limestone, &c., and great works of every kind, 

 to which they have been conducted, and to which a large portion of them owe their rise, are their best 

 recommendation. In short, it may be concluded, that no canal can be completed and brought into use, 

 but the inhabitants and the agriculture of the district will shortly feel great benefit from it, whatever may 

 be the result to the proprietors. 



3801. The great advantages of canals as means of transport result from the weight which may be moved 

 along by a small power. The velocity with which boats can be drawn along a canal is confined within 

 very narrow limits, owing, as Edgeworth has observed, to the nature of the resistance to which they 

 are exposed ; this resistance increasing in a geometrical proportion, as the squares of the velocity with 

 which the moving bQdy is impelled : whereas, on roads or railways, an increase of velocity requires only 

 an arithmetical increase of power. Or, in other words, to draw a boat with ten times a given velocity, 

 would require a hundred times as much power as was requisite to draw it with that given velocity ; 

 wiiereas, to dra\y^ carriage on a road or railway with ten times a given velocity, would require only 

 ten times the given power. For this reason, however advantageous canals may have been found, for 

 transporting heavy loads, they will be found upon trial inferior to roads in promoting expedition. 



3802. Canals appear to have been first made in Egypt. Though less attended to 

 by the Romans than roads, yet they formed some in this country near Lincoln and 

 Peterborough. 



3803. China is remarkailefor its canals, and there are said to be many in Hindostan, though we believe 

 they are principally for the purpose of irrigation. In Russia there are some, and several in Sweden ; 

 one or two in Denmark ; some in Germany ; and a great many in Holland. The canal of Burgundy 

 in France was commenced under Henry IV. ; and that of Languedoc finished by Riquet, the Brindley 

 of France, under Louis XIV. Some attempts have been made to form canals in the hilly country 

 of Spain ; and a great many excellent ones are executed in America. 



3804 Navigable canals in Britain took their rise between 17.?5 and 1760, by the Sankey Brook Com- 

 pany in Lancashire ; but the great impulse wasi^jven by the duke of Bridgewater about 17.57, when he 

 first commenced, under the direction of BririiUey, the canal between his cdal-works at Worsley and 

 Salford. The duke of Bridgewater has, in consequence, not improperly been called the father of canals 

 in England ; while his engineer, Brindley, by his masterly performances on the duke of Bridgewater's 

 canal, altered and extended as the scheme thereof was by the three subsequent acts of parliament, has 

 secured to himself, and will, it should seem, (from a comparison of the great features and minutise 

 of execution in this the first canal, with most others in this country, even of the latest construction,) 

 long continue to hold that rank among the English engineers, to which Riquet seems entitled among 

 foreigners. 



3805. Since the duke of Bridgewater's time, the extension of canals in the British Isles has been rapid. 

 A number of scientific engineers have arisen, of whom we need only mention Smeaton, Rennie, and Tel- 

 ford, and point to the Caledonian canal. 



Sect. II. Of discovering the most eligible Route for a Line of Canal. 



3806. The first object, vthen the idea of a canal is determined on by a few^ landed pro- 

 prietors, is the choice of a skilful and experienced engineer. Such an artist should 

 undoubtedly possess a considerable degree of mathematical knowledge. Calculations, 

 of which some are of the most abstruse and laborious kind, will frequently occur ; and 

 he should, therefore, be well acquainted with the principles on which all calculations are 

 founded, and by which they are to be rightly applied in practice. An engineer should 

 also have studied the elements of most or all of the sciences immediately connected with 

 his profession ; and he should particularly excel in an acquaintance with the various 

 branches of mechanics, both theoretical and practical. His knowledge should compre- 

 hend whatever has' becii written or done by other engineers ; and he should have inform- 

 ation in every department of his business, from an accurate examination of the most 

 considerable works that have been executed, under all the various circumstances that are 

 likely to occur. It is necessary that he should be a ready and correct, if not a finished, 

 draughtsman. He should also be conversant with the general principles of trade and 

 commerce ; with the various operations and improvements in agriculture ; with the 

 interests and connection of the diiferent owners and occupiers of land, houses, mills, &c. ; 

 and with all the general laws and decisions of courts pertaining to the objects connected 

 with his profession. By an extensive acquaintance with the disposition, inclination, and 

 thickness of the various strata which compose the soil or land of the British Islands, he 

 will be able to avoid many errors incident to those who are destitute of this knowledge. 

 As the last, though not the least, of these qualifications of an engineer, which we shall 

 enumerate, he should be a man of strict integrity. 



3807. A proper engineer being fixed upon, the adventurers should not tie him down too closely by 

 re.-itrictions as to time; but allow him leisure to consider, digest, and revise, again and again, the different 

 priijects and ways, which will, in most instances, naturally present themselves to him in an extensive and 

 th()rough investigation. The engineer should be allowed to choose and employ the most competent 

 assistants, and to call in and occasionally to consult the opinions of eminent or practical men, as land- 

 surveyors, agents of the neighbouring landed property, the principal and most expert commercial men of 

 the district who are best acquainted with its trade and wants, any eminent miners, &c. &c. ; and such 

 men the engineer should be authorised liberally, and at once, to remunerate for their services and intelli- 

 gence. Previously to the beginning of any minute survey or system of levelling, the engineer ought to 

 visit all the objects within the district under consideration, and endeavour to make a just estimate and 

 preserve memorandums of them ; as of the trade and importance of all the towns likely to be affected by 

 the undertaking ; of all mines of coal, iron, &c., quarries of limestone, freestone, slate, &c., or the situation 

 where such can be found ; of all the manufactorirs of heavy and cumbrous goods, and other extensive 

 works ; and generally of every thing likely to furnish tonnage for a canal. The most eligible route for a 

 canal being settled in the engineer's mind, he will then proceed to m.ake a rough calculation of the quan- 

 tity of goods of each kind which may be expected to pass upon the line in a given time; he will also 



