780 



NEW YORK STATE MUSEUM 



was greater than 2 feet. A series of experiments was accord- 

 ingly made at Cornell University, extending the results up to G 

 feet. 



Bridges. The railway and highway bridges were designed for 

 250 feet clear span on the 30-foot channel and 240 feet on the 21- 

 foot. In a few cases of highway crossings steam ferries were 

 provided for instead of bridges. 



Unit prices. In establishing unit prices for the estimates the 

 prices paid on large works throughout the country, involving 

 similar constructions, were considered and the advice and opinion 

 of most of the experienced contracting engineers was secured. 



Control of Lake Erie. Under the influence of varying supply, 

 evaporation and discharge, the monthly mean level of Lake Erie 

 has varied 4.6 feet during the past seventy years. The low level 



Fig. 60 Rock cross-section of proposed Barge canal. 



occurs from September to November, when navigation is the most 

 active. In order to maintain the level the discharge must be so 

 controlled that it will always be approximately equal to the dif- 

 ference between the water supply and the evaporation of Lake 

 Erie. This can be accomplished by establishing regulating works 

 at Buffalo. They must be so arranged that they will not only 

 maintain the level of the lake at or near the fixed stage adopted, 

 but will also produce no injurious effect upon the lakes and water- 

 ways from which the supply is derived, or upon those receiving 

 the discharge. This problem was investigated by the Board of 

 Engineers, and they concluded that the best location for the regu- 

 lating works would be at the foot of the lake, just below Buffalo 

 harbor. The board also concluded that the level of the lake could 

 be maintained during the season of navigation within about 0.6 

 foot below the level adopted for regulation, under all the condi- 

 tions of supply. Variations of level, due to violent winds, will 



