Page:Popular Science Monthly Volume 66.djvu/504

500 the flow, the length of the entire crest of the Falls on both sides (4,070 feet) and the difference in elevation of the sill of the Falls, has calculated that when the flow is reduced to 184,000 cubic feet per second, or by 40,000 cubic feet, the water will be down to the present rock bottom at the edge of the American shore.

Then the American Falls, though still forming a cataract, will be but a ghost of their ancient magnificence; instead of the mighty sheet of emerald waters now spreading in silent majesty over the rock crest, a weakly, thin, white apron of waters carried forward by a slender impulse a tergo and the great cadence will have lost its glory. Electric searchlights in all the colors of the rainbow dancing up and over the falling waters and other factitious means of producing a spectacle will never compensate the loss.

Let one fifth more of the water be abstracted beyond the line we have already calculated and the American channel will be dry. That is, in effect, double the amount of 40,000 cubic feet, and when 80,000 cubic feet have been taken away from the present flow the Canadian channel will still be an interesting object, but the American Falls will be wholly gone.

All our figures in these statements and calculations, it may be well to repeat, are taken from the reports of the United States engineers, of the power companies' engineers, or have been specially derived at my solicitation by engineers of high standing.

We may return to the data given concerning present and immediately contemplated abstraction.

The two American and three Canadian companies now in