A PROPOSITION FOR AN ARTIFICIAL ISTHMUS. 473 



an opportunity of utilizing the tidal power. There is a continuous 

 flow from the north (due in the first place to the Gulf Stream), 

 estimated at between one and two hundred cubic miles per day. 

 If a dam were thrown across, the effect would be to turn the Irish 

 Sea into a bay and to bank the waters of the North Sea a number 

 of feet higher on the north side of the dam than the level of the 

 now Irish Channel on the south. From this difference of levels 

 an unlimited quantity of power could be drawn. One can get a 

 faint conception of the amount that would be on tap by compar- 

 ing the case with that of the utilization of the energy of the Falls 

 of Niagara. There is at present in course of construction at the 

 falls a vast scheme of power development which will supply one 

 hundred thousand horse power day and night all the year round. 

 The amount of water which this will take will be insignificant 

 compared with the total quantity going over the falls, which is 

 roughly estimated at three hundred and fifty thousand tons per 

 minute, and one hundred thousand horse power will be developed 

 by about thirteen thousand tons per minute. The total power on 

 the falls is thus some twenty-seven times the one hundred thou- 

 sand horse power. This total quantity of water amounts to about 

 one cubic mile every nine days, and the volume of water running 

 through the Irish Channel is about one hundred and fifty cubic 

 miles daily. Of course, the number of feet of fall is many times 

 greater at Niagara than it would be at the proposed dam, but even 

 so the total horse power available at the dam would be more than 

 fifty times that of the whole of the Niagara Falls. 



The site of the proposed undertaking is between the head- 

 lands of Antrim and Cantire. On both sides the ground is de- 

 scribed as high, and on the Irish side there rise several peaks 

 of considerable height, viz., from nine to twelve hundred feet. 

 These are sufficiently near the shore to be used to dig materials 

 from to be gravitated down to the dam, and the fact is of great 

 importance in connection with reducing the expense of the work 

 by doing away with the necessity for power for the traction of 

 these materials. 



The channel is, as has been said, some fifteen miles in width 

 and of varying depth. The average depth is about three hundred 

 feet, and the maximum is given by Mr. Lodian, in the Electrical 

 Engineer of January 24th last, as four hundred and seventy-four 

 feet ; in many places it is as little as two hundred. The bottom 

 is described as of " shells, stones, and rock," which would proba- 

 bly hardly settle at all under the weight of the dam. The current 

 is six or eight miles an hour, varying somewhat at different points 

 in the cross-section of the channel. The total quantity of material 

 necessary to form the dam or isthmus would be in the neighbor- 

 hood of five hundred million cubic yards. One can imagine that 



VOL XLV. 37 



