Journal of electricity, power, and gas . 1 5th 10 years— 1889-1898. 6th 10 years— 1S99-1908. .563 .562 .530 .52S 47,800 42,900 46,400 34,100 40,600 .547 43,100 2,1602,4302,5002,3402,2702,190 . In Fig. 4 are shown the hydrographs for thisstream. Again the direct relation between precipitationand runoff is apparent from the general parallelismof these two curves. The total runoff per inch of pre-cipitation shows a slight decreasing tendency coin-cident with an increase in forest cover. This is op-posed to the forestry theory and substantiates
Journal of electricity, power, and gas . 1 5th 10 years— 1889-1898. 6th 10 years— 1S99-1908. .563 .562 .530 .52S 47,800 42,900 46,400 34,100 40,600 .547 43,100 2,1602,4302,5002,3402,2702,190 . In Fig. 4 are shown the hydrographs for thisstream. Again the direct relation between precipitationand runoff is apparent from the general parallelismof these two curves. The total runoff per inch of pre-cipitation shows a slight decreasing tendency coin-cident with an increase in forest cover. This is op-posed to the forestry theory and substantiates the be-lief that forests use large quantities of water, andhence always reduce the runoff. However, it is muchmore reasonable to believe that these changes areclue to variations in precipitation and have occurred 4 Ibid p. 15 entirely independent of the forests. The uniformityratio is seen to be highest when the forest area wasleast, in the fourth period, but the hydrographs showthis to be a period of low rainfall, which readily ac-. /ooa Figr. 4.—Merrimac River (at Lawrence, Mass), Chart. counts for it. The uniformity of flow on this streamhas not sensibly changed during the period of slight variations must be attributed to the pre-cipitation and not to forests. (To be continued.) The resistance of the soil varies greatly with tem-perature within the ordinary range encountered inpractice. Even at about freezing temperatures theresistance will be several times that at summer tem-peratures. This not only has an important bearingupon the magnitude of the electrolysis trouble thatmay occur at different seasons, but also indicates thatwhere practicable voltage surveys should not be madewhen extremely low temperatures prevail. Interesting wireless telegraph statistics relatingto the year ending December 31, 1912, have been givenout by the Bureau of the Census. The figures pre-sented show that while there was a net deficit in op-eration in 1907, a net income was the
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