WORKS FOR CREATING SLACKWATER. 137 



trict possesses any natural wealth the wisdom of the course will soon become 

 apparent. 



A valuable lesson in this respect may be drawn from the Seine, where the first 

 system of slackwater between Paris and Rouen was established between 1838 and 

 1853, at a cost of about $2,800,000, affording a depth of water 5^ feet.* Soon 

 after its completion the improvements in railroad transportation caused serious 

 inroads on the river traffic, and it finally became evident that if the latter were 

 to be kept in existence the system must be enlarged. Accordingly, between 1858 

 and 1878 new locks and dams were built, and the capacity of the old ones increased 

 to a draught of 6$ feet. The cost of these changes was about $2,800,000. The 

 relief, however, was only temporary, and between 1878 and 1888 a further expendi- 

 ture of $12,200,000 was incurred, securing a depth of water of io feet, and the 

 result has been the creation of an immense and increasing traffic on the river, and a 

 general development of the valley. 



A similar example has been afforded by the St. Mary's Falls Canal, in Michigan, 

 between Lakes Superior and Huron, through which passes most of the interstate com- 

 merce of the Great Lakes. The first canal with its lock was completed in 1855 at a cost 

 of about a million dollars. In 1870 enlargements had to be commenced, which were 

 finished in 1881, and cost over two million dollars. These soon proved insufficient, 

 and in 1887 more extensive work was begun, including a lock 800 feet long and 100 

 feet wide, which was completed in 1896 and provided a depth on the sills of 21 feet. 

 The cost of the last improvements was $3,700,000 but it is nevertheless becoming 

 evident that further accommodation must be provided before many years. 



Similar demands are being made at other points in this country, and it is becom- 

 ing apparent that if river traffic is to hold its ground many of the existing systems 

 must be enlarged. At present most of our new locks are designed for a depth of six 

 feet on the sills, but it would be much better to provide for eight or nine feet. 



Size of Lock. It may be taken as an axiom for similar reasons, that it is better 

 to build a lock too large for present needs, than only large enough. The trend of 

 modern transportation is toward cheap rates, which means larger boats and greater 

 draught of water, and if rivers are to hold their own in competition with railroads, it 

 will be necessary to improve them with this in view. A railroad must renew its rails and 

 rolling stock because of wear, and can then make them suitable to modern demands, 

 but a lock once built can only be changed by a special and very heavy expense, which 

 could have been avoided at the outset for a small part of the cost. 



We are acquainted with one instance of a small lock which proved of practically 

 little value, since the only boats which could utilize it had to be of small tonnage, and 

 could not carry much freight, and the expenses were consequently too high in propor- 

 tion to the profits. Several boats attempted to establish a trade, but all met with the 



* Canalisation de la Seine, Boul6, 1889. 



