Mr. Allen on the Volume of the Niagara River. 71 



of six hundred and sixty feet apart.* After thus obtaining three 

 cross sections of the volume of the current, whereby its area or 

 dimensions were ascertained, the velocity of the surface was then 

 found in ten different places between these three lines, by noting 

 the time in which floating bodies set adrift in different parts of 

 the width of the river, were borne down from one sectional line 

 to the distance of six hundred and sixty feet to the next sectional 

 line below it. All these admeasurements were made with every 

 attention to accuracy. 



Having thus found by experiment the velocity of the surface 

 of the stream, the average or mean velocity of the bottom and 

 middle, as well as of the surface, was ascertained by means 



of the formula established by Eytelwein I V=t^x9) which for 



measuring the volume of water flowing in rivers of great depth, 

 I consider to be a closer approximation to accuracy than those es- 

 tablished by Prony and other philosophers, who have investigated 

 the subject of the discharge of water flowing down the inclined 

 planes of the beds of rivers. These calculations have been care- 

 fully revised ; and the results stated may therefore be deemed as 

 a sufficiently accurate estimate of the volume of water that flows 

 from Lake Erie. 



Allowing about 374,000 cubic feet of water (by estimate) to 

 flow through the harbor of Black Rock per second, as indicated 

 on the map, the results of these calculations show, that about 

 22,440,000 cubic feet, or 167,862,420 gallons, weighing 701,250 

 tons, or 1,402,500,000 lbs. of water, flow out of Lake Erie every 

 minute, and become precipitated over the cliffs of rocks at the 

 grand cataract of the Falls of Niagara. 



Estimating the perpendicular descent of the waters of the 

 grand cataract to be one hundred and sixty feet, and making the 

 usual allowance of one third part for waste of effective power in 

 the practical application of water to water-wheels ; and also esti- 

 mating the power of a horse to be equal to a force that will raise 

 a weight of 33,000 pounds one foot high in one minute, which is 

 Watt and Boulton's standard, v/e obtain the following results : 



* In the preceding map the left hand column of figures in each section represents 

 the distance of each sounding from the American shore, and the right hand column 

 the depth of the soundings. The distance of the soundings from each other may be 

 found by subtracting each measurement from the one next above it. The arrow 

 denotes both the direction of the current and the point of compass. 



