280 NOTES. — ORIGINAL AND SELECTED. 



quantities of salt required for domestic use before the employ- 

 ment of it in manufactures, and may serve to show that in 

 England the making of salt from sea -water must have been a 

 great industry prior to the discovery of rock-salt.— Ed. 



Water Power from the Thames.—" Mr. T. B. Stoney, 

 M. Inst. C.E.I. (Raphoe, co. Donegal), in an interesting letter on 

 the question of power for the metropolis, draws attention again 

 to the water power in the estuary of the Thames, which could 

 probably, he states, be made available in large quantities for 

 industrial purposes by simple and inexpensive works. He 

 instances those reaches of the river in which there is a mean 

 tidal rise of 16^ feet. In the Essex marshes bordering the 

 Thames, he remarks that there are extensive tracts of land at a 

 level of several feet below high water mark. In these marsh 

 basins reservoirs could be constructed, which would be filled by 

 the tide every twelve hours to a depth of (say) five feet at mean 

 high water. When the tide falls, he proceeds, the outflow from 

 these reservoirs into the sea could be used to drive pumps, which 

 would raise water out of the reservoirs to a height of 6 feet above 

 mean high water to feed turbines. These turbines, fixed at low 

 water, would be driven under an average head of i6j feet. When 

 the tide rises within 4 feet of high water, the discharge of the 

 turbines into the sea would be stopped and diverted into the now 

 empty reservoirs. By this arrangement, our correspondent 

 concludes, the turbines would produce energy for commercial 

 use for 24 hours continuously." — The Times, Feb. 14, 1906, 

 Engineering Supplement. 



[End of Volume A77.] 



