272 Mr. Thomas Commerford Martin [June 19, 



parallel with the canal outside. Here the water gets a fall of about 

 140 feet before it smites the turbines. The arrangement of the 

 dynamos generating the current up in the power house, is such that 

 each of them may be regarded as the screw at the end of a long shaft, 

 just as we might see it if we stood an ocean steamer on its nose with 

 its heel in the air. At the lower end of the dynamo shaft is the tur- 

 bine (Fig. 2) in the wheel pit bottom, just as in the case of the steamer 

 shaft we find attached to it the big triple or quadruple expansion 

 marine steam engine. Perhaps we might compare the dynamo and 

 the turbine to two reels, stuck one each end of a long lead pencil, so 

 that when the lower reel is turned the upper reel must turn also. 

 You might also compare the dynamos to bells up in the old church 

 steeple, and the turbines to the ringers in the porch, playing the 

 chimes and triple bob majors by their work on the long ropes that 

 hang down. The wheel pit which contains the turbines is 178 feet 

 in depth, and connects by a lateral tunnel with the main tunnel 

 running at right angles. This main tunnel is no less than 7000 feet 

 in length, with an average hydraulic slope of 6 feet in 1000. It has 

 a maximum height of 21 feet, and a width of 18 feet 10 inches, its net 

 section being 386 square feet. The water rushes through it and out 

 of its mouth of stone and iron at a velocity of 26J feet per second, or 

 nearly 20 miles an hour. 



More than 1000 men were employed continuously for more than 

 three years in the construction of this tunnel. More than 300,000 

 tons of rock were removed, which have gone to form part of the new fore- 

 shore near the power house. More than 16,000,000 bricks were used 

 for the lining, to say nothing of the cement, concrete and cut stone. 

 The labour was chiefly Italian. The brick that fences in the headlong 

 torrent consists of four rings of the best hand-burned brick of special 

 shape, making a solid wall 16 inches thick. In some places it is 

 thicker than that. Into this tunnel discharges also by a special sub- 

 tunnel, the used-up water from the water wheels of the Niagara Falls 

 Paper Co. The turbines (Fig. 3) have to generate 5000 horse-power 

 each, at a distance of 140 feet underground, and to send it up to the 

 surface. For this purpose the water is brought down to each by the 

 supply penstock, made of steel tube and 7J feet in diameter. This 

 water impinges upon what is essentially a twin wheel, each receiving 

 part of the stream as it rushes in at the centre, the arrangement being 

 such that each wheel is three stories high, part of the water in the 

 upper tier serving as a cushion to sustain the weight of the entire 

 revolving mechanism. These wheels, which have thirty-two buckets 

 and thirty-six guides, discharge 430 cubic feet per second, and they 

 make 250 revolutions per minute. At 75 per cent, efficiency they 

 give 5000 horse-power. The shaft that runs up from each one to the 

 dynamo is of peculiar and interesting construction. It is composed 

 of steel f inch thick, rolled into tubes which are 38 inches in diameter. 

 At intervals this tube passes through journal bearings or guides that 

 steady it, at which the shaft is narrowed to 11 iaches in diameter and 



