+--------------------------------+----------+-----------+ | |Pounds per|Dollars per| | | Kilowatt | Generator | | | Mile. | Kilowatt. | +--------------------------------+----------+-----------+ |Wilbraham to Ludlow | 0.86[A] | 1.11 | |Sewall’s Falls to railroad shops| 2.7 | 2.25 | |Into Victor, Colo. | 0.9 | 1.50 | |To Dales, Ore. | 1.2 | 5.10 | |Apple River to St. Paul | 2.1 | 7.95 | |Farmington River to Hartford | 3.2 | 10.80 | |Cañon City to Cripple Creek | 1.6 | 5.85 | |Yadkin River to Salem | 2.6 | 5.85 | |Montmorency Falls to Quebec | 11.2 | 11.85 | |Cañon Ferry to Butte | 1.7 | 17.25 | |San Gabriel Cañon to Los Angeles| 2.6 | 9.85 | |Welland Canal to Hamilton | 1.7 | 9.45 | |Madrid to Bland, N. M. | 6.6 | 31.80 | |Ogden to Salt Lake City | 3.5 | 19.35 | |Santa Ana River to Los Angeles | 3.5 | 44.25 | |Colgate to Oakland | { .56 | 24.15 | | | { .27[A] | | +--------------------------------+----------+-----------+ [A] Aluminum.
Of the seven transmissions using between 36 and 79 pounds of copper for each kilowatt of generator capacity, four have voltages ranging from 827 to 1,000 per mile, and on only one is the pressure as low as 643 volts per mile. Five transmission lines vary between 115 and 295 pounds of copper, or its equivalent, per kilowatt of generator capacity, and their voltages per mile are as high as 769 in one case and down to 281 in another. Allowing for some variations in the percentages of loss in transmission lines at full load, the fifteen plants plainly illustrate the advantage of a high voltage per mile, as to the weight of conductors. This advantage is especially clear if the differences due to the lengths of the transmissions are eliminated by dividing the weight of conductors per kilowatt of generator capacity in each case by the length of the transmission in miles. This division gives the weight of conductors per kilowatt of generators for each mile of the line, which may be called the weight per kilowatt mile. For the Ludlow transmission this weight is only 0.86 pound of aluminum, the equivalent of 1.72 pounds of copper, while the like weight for the line into Quebec is 11.2 pounds of copper, or 6.5 times that for the former line. But the voltage per mile on the Ludlow is 3.2 times as great as the like voltage on the Quebec line.