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HISTORY OF ENGINEERING.

Book I.

the Loire was the principal object to which the attention of the government should bedirected, in 1689, employed Thomasin, a royal engineer, to examine the projects of thecanals proposed in Burgundy ; this engineer chiefly directed his attention to the canal ofCharolais , and it appears that he took the levels from the Saone to the Loire , but the un-fortunate termination of the reign of Louis XIV . was not favourable for such works. Underthe Regency, Thomasin was employed in 1719, at the request of Vauban , the nephew of theMarshal, and the members for Burgundy, to examine two other projects ; but he finallydetermined on that of Charolais ; he laid down a plan in 1720, and made a report whichwas approved by Sebastien, member of the academy, and M. Rcgemort. Many otherengineers were at various times employed in surveying and reporting upon this celebratedcanal, but it was not till 1783 that letters patent were issued, when Gauthey the engineer,traced out the line, and the work was commenced at the end of April in that year. Com-panies of pioneers and ground diggers were appointed with clerks of the works over them,and troops assisted in the various operations. Each regiment employed sent at a time372 men, commanded by ten officers, two of whom were present; each company of twelvemen encamped together, and the work was so set out, that a certain quantity was completedevery twelve days. The soldiers did not take out the lowest excavations, that being left tostronger men. At the end of every fortnight, a measurement was taken of the work per-formed by each company, as well as of that which remained unfinished ; and a report wasmade by the surveyor, which was sent to the engineer-in-chief, and submitted in case ofdispute to the superior officer of the departments; three hours per day were allowed formeals ; a change took place about every fortnight. The troops were employed for threeyears, and performed work to the amount of 288,400 livres, which was about a tenth of thesum required for the completion. The whole length of the canal was divided into eightand then into ten stations, to each.of which a commissioner was attached, who made everyday a survey of the works in their divisions, numbered the workmen, planted the piquetsfor the direction and levels, and took care that the work was executed conformably to theinstructions given ; they also measured the masonry, and gave in the accounts of the con-tractors, no new measurement being made till the former one had been paid. They re-gistered the number of workmen employed, and the quantity of work done, and at the endof the month abstracted the whole ; the tools, of which they defrayed the expense, were alsounder their care, those lost being replaced at the cost of the workmen.

The heights of the various locks were set out by the engineer of the canals, who madethe drawings for their execution. This celebrated canal, uniting the Loire at the Saone ,has its mouth on the first of these rivers at Digoin ; it follows the Arroux, then the leftbank of the Bourbince, passing through Paray, Genelarde, Ciry, Blanzy, to the Lake ofMont Chanin, where the navigation commences; at some distance from the lake, the canalseparates the Lake of Longpendu into two parts, and then passes by the side of the leftbank of the Dheune to St. Julien, where it traverses the valley, following the right bank ofthe Seine , and passing through St. Berain, St. Leger, Dennevis, St. Gilles, and Remigny;it afterwards traverses by Chagny, near the left bank of the Thalie, and passing throughFragnes and Champfergueil, runs into the Saone at Chalons .

The level of the “ point de partage ” being determined, the line of the canal was setout, by fixing stations on the hills, by means of the spirit level, and the platforms of thelocks were determined, the ground between each lock was then accurately levelled, andprofiles were drawn on the ground at the distance of every 64 feet, on which the centreof the canal was marked; care being taken to regulate ihc cuttings, and make themequal to the embankments, agreeable to a table previously constructed, which indicatedthe depth they were to dig, according as the fall was greater or less; the points wereset out on the ground, and rectified so as to avoid too great a bend, and form ratherright lines or great curves: the level lines being drawn above or below a lock, a rightline was sought about 390 feet in length, which should unite with the two preceding,without making too sharp an angle; in the midst of which was placed the lock, exceptwhere the ground offered a proper fall. The ordinary breadth of the canal is 32 feet atthe bottom, and 48 feet at the level of the water, the depth being 5 feet; at this level is aset-offi 18 inches in width, on which grows the flag or some other aquatic plant; at18 inches above the water are two other sets-off, one serving as the towing path, havingfrom 10 to 20 feet of width; the other being 6 feet wide, unless the height exceeded thatdimension; in all cases the width was made equal to the height. The fall of its talus ingood ground is one and a quarter, on sandy ground one and a half, and where subject toinundation, two. The sets-oft' have a counter slope of one-forty-eighth to prevent the rainwater entering the canal ; at the foot of the bank, on the land side, is a ditch of variouswidths to receive the rain water, which is conducted under the aqueducts traversing thecanal; its ordinary width at the bottom is 65 centimetres. In the parts where the canal isbacked by steep hills, two ditches are made at some distance apart, one above the other ;there is also a ditch at the foot of the talus on the valley side, to receive the water which mayfilter from the canal, and to prevent cattle from doing injury to the banks. Care was taken