October 6, 192 1] 



NATURE 



183 



obtained from hydro-electric stations. In France 

 much of the track of the Compag-nie du Midi in 

 the region of the Pyrenees has been electrified 

 with the aid of water power ; much of the Swiss 

 railway system has been electrified ; and the elec- 

 trification of many other trunk lines on the Euro- 

 pean continent is at present under consideration. 



Quite apart from the probable huge demand in 

 the distant future for energy for the manufacture 

 of artificial fertilisers by some system of nitrogen 

 fixation, agriculture would appear to offer a 

 promising field for the use of hydro-electric power. 



Much energy is now being utilised in the U.S.A. 

 for purely agricultural purposes. In California, 

 for example, there is in effect one vast system of 

 electrical supply extending over a distance of 800 

 miles with 7200 miles of high-tension trans- 

 mission lines. This is fed from seventy-five 

 hydro-electric stations, inter-connected with forty- 

 seven steam plants, to g'ive a total output of 

 785,000 horse-power. A further group of 

 thirteen hydro-electric schemes now under con- 

 struction will add another 520,000 horse-power. 

 A large proportion of this power is used in agri- 

 culture, and a census in 191 5 showed that elec- 

 tric motors equivalent to more than 190,000 horse- 

 power were installed on Californian farms. The 

 Californian rice industry is almost wholly depen- 

 dent on irrigation made possible by electric 

 pumping, while most of the mechanical processes 

 involved in farming are being performed bv elec- 

 tric power. 



There can be little doubt that the economic 

 development of many of our tropical dependencies 

 is bound up in the development of their water- 

 power resources. Not only would this enable 

 railroads to be operated, irrigation schemes to be 

 developed, and mineral deposits to be mined and 

 worked, but it would also go far to solve the black 

 labour problem, which promises to be one of some 

 difficulty in the near future. 



While those outlets for electrical energy which 

 are now in sight promise to absorb all the energy 

 which can be cheaply developed for many years 

 to come, there are many other probable directions 

 in which cheap energy would find a new and profit- 

 able outlet. Among these may be mentioned the 

 purification of municipal water supplies, the 

 sterilisation of sewage, the dehydration of food 

 products, and the preservation of timber. 



Research in Hydro-Electric Problems. — There 

 are few branches of engineering in which research 

 is more urgently required and in which it might 

 be more directly useful. 



Among the many questions still requiring in- 

 vestigation on the civil and mechanical side may 

 "be mentioned : — 

 ^ I. Turbines. — Investigation of turbine corro- 

 sion as affected by the material and shape of the 

 vanes. 



Effect of erosion due to sand and silt. 



Resistance to erosion offered bv different 

 materials and coatings. 



Bucket design in low head high-speed turbines. 



Draft tube design. 



NO. 2710, VOL. 108] 



Investigation of the directions and velocities of 

 flow in modern types of high-speed turbines. 



Investigation of the degree of guidance as 

 affected by the number of guide and runner vanes. 



2. Conduits and Pressure Tunnels. — The 

 design of large pipe lines under low heads with 

 the view of reducing the weight of metal. The 

 investigation of anti-corrosive coatings, so as to 

 reduce the necessity for additional wall thickness 

 to allow for corrosion. 



Methods of strengthening large thin-walled 

 pipes against bending and against external 

 pressures. 



Methods of lining open canals and of boring and 

 lining pressure tunnels. 



Effects of curvature in a canal or tunnel. 



3. Dams. — Most efficient methods of construc- 

 tion and best form of section especially for rock- 

 fill and earthen dams. Best methods of produc- 

 ing water tightness. 



4. Run-off Data. — Since the possibility of 

 designing an installation to develop the available 

 power efficiently and economically depends in 

 many cases essentially on the accuracy of the run- 

 off data available, the possession of accurate data 

 extending over a long series of years is of great 

 value. 



While such data may be obtained either from 

 stream gaugings or from rainfall and evapora- 

 tion records, the former method is by far the more 

 reliable. For a reasonable degree of accuracy, 

 however, records must be available extending over 

 a long period of years, and at the present moment 

 such data are available only in very few cases. 



Where accurate rainfall and evaporation records 

 are available, it is possible to obtain what is 

 often a sufficiently close approximation to the 

 run-off, but even rainfall records are not generally 

 at hand where they are most required, and even 

 in a district where such records are available, they 

 are usually confined to easily accessible points, and 

 are seldom extended to the higher levels of a 

 catchment area where the rainfall is greatest. 

 Even throughout the United Kingdom our know- 

 ledge of the rainfall at elevations exceeding 500 ft. 

 is not satisfactory, and little definite is known 

 concerning that at elevations exceeding 1000 ft. 



In this country evaporation may account for 

 between 20 and 50 per cent, of the annual rainfall, 

 depending on the physical characteristics of the 

 site, its exposure, mean temperature, and the type 

 of surface covering. In some countries evapora- 

 tion may account for anything up to 100 per cent, 

 of the rainfall. As yet, however, few records 

 are available as to the effect of the many variables 

 involved. An investigation devoted to the ques- 

 tion of evaporation from water surfaces, and from 

 surfaces covered with bare soil and with various 

 crops, under different conditions of wind, expo- 

 sure, and mean temperature, would appear to be 

 urgently needed. If this could be combined with 

 an extension of Vermeulle's investigation into the 

 relationship between rainfall, evaporation, and 

 run-off on watersheds of a few characteristic 

 types, it would do much towards enabling an accu- 



