174 



NA TURE 



[April 7, 1910 



rapids at a place where the current is very swift. To 

 exclude the former trouble, the following precautions have 

 been taken : — a long and tapering forebay, protected at 

 the entrance by the main intake, terminates at its narrow 

 down-stream end in a deep spillway. Upon the river side 

 it is enclosed by a submerged wall, while the other side, 

 near the spillway, is occupied by the main screen building 

 leading to the inner bay and to the portals and headgates 

 of the three conduits. 



The intake, which is nearly 600 feet long, stretches 

 across the inlet at DufTerin Island almost parallel with 

 the current in the river. Throughout its whole length, a 

 concrete curtain wall extends down 9 feet into the water, 

 which is 15 feet deep at this spot, so that the gate openings 

 beneath admit only deep water, and this at right angles 

 to the swift exterior surface f^ow, which, sweeping the full 

 length of the curtain wall, carries the floating ice past to 

 the rapids beyond. 



The intake is divided into twenty-five bays, through 



' to the inner ba}-, and parallel with the direction of flow 

 in the outer bay. Here again a curtain wall formed by 

 the front wall of the superstructure admits only deep 

 water to the screens at right angles to the main current, 

 while it also excludes ice with the surface currents main- 

 tained through the forebay by a huge spill of surplus 

 water. At the gate structure, where the water is 30 feet 

 deep, the tapering portals leading to the electrically operated 

 Stoney headgates are protected with wide-meshed screens, 

 which are also enclosed and safeguarded by a curtain 

 carried by the front wall of the gate-house. There is ary 

 ample ice-run from the bay in front of the curtain to the- 

 river, and both at the headgates and screens an open canal 

 spills into a gravity ice-run emptying into the river. Both 

 buildings are supplied with steam for heating and thaw- 

 ing from an underground boiler plant, and the author can 

 testify to the entire success of the heating. It was a bitterly 

 cold day, snowing and freezing hard, with a nasty wind, 

 but inside these houses it was almost unpleasantly hot, in^ 



. ^5 •<r-"*ifcJi3AUOT"^ 



pOWtR HOUSE 



•^LONDON 



Power Sub-StcUioThe o 



Fig. I.— Power District of Niagara Falls. 



which the water is admitted at a velocity of 5 feet per 

 second. Provision is made for inserting stop-logs into 

 each of the twenty-five openings in order to regulate the 

 flow of water. 



The outer forebay has an area of 8 acres, and a 

 depth ranging from 15 to 20 feet, and is bounded on its 

 down-stream side by a submerged wall or dam 725 feet 

 long, terminating at the down-stream end of the screen- 

 house, which is 320 feet long, built of reinforced concrete 

 faced with Roman stone. 



The inner forebay is 2 acres in area with a depth of 

 20 to 30 feet, whilst the gate-house, similar in construc- 

 tion to the screen-house, is 120 feet long and divided into 

 six bays, two for each of the main conduits. The i8-foot 

 " Stoney " gates which guard the entrances to the conduits 

 weigh 18 tons each, or 36 tons including the counter- 

 balance. They were built by Ransomes and Rapier, and 

 are operated by electric motors of 5 horse-power capacity. 



At the main screen the same precautions for • the ex- 

 clusion of ice are repeated. This structure, which is 320 feet 

 in length, in 20 feet depth of water, lies across the entrance 



NO. 2 no, VOL. 83I 



spite of the large masses of ice-cold water coming in con- 

 tinuously from the river. The water before entering the 

 conduits must pass through three automatically selective 

 steps, each excluding ice, and, in addition, through two 

 screens, each behind ice-runs, in heated buildings contain- 

 ing live steam for emergencies, and the experience of three 

 winters has proved the above plan of excluding and pre- 

 venting the formation of ice to be an entire success- 

 record which is unprecedented for power plants in a 

 climate like that of Niagara. 



An electric overhead travellitig-crane runs along the 

 screen-house for removing the screen-frames for cleaning 

 and changing when necessary, and as this building is 

 situate in the park the roof is flat and finished off as a 

 promenade, access being obtained from the outside by 

 broad steps at either end of the building, and from this 

 point a magnificent view of the upper rapids is obtained. 



Main Conduits. — These are of o-s-inch rivetted and re- 

 inforced steel embedded in concrete 18 feet and 20 feet in 

 diameter and 6500 feet long, sunk beneath the surface of 

 the park. The water flows through them at an approxi- 



