The DC motor was the mainstay of electric traction drives on both electric and diesel-electric locomotives, street-cars/trams and diesel electric drilling rigs for many years. The introduction of DC motors and an electrical grid system to run machinery starting in the 1870s started a new second Industrial Revolution.
One acre is 43,560 sq ft. One half acre is 21,780 sq ft. However, that doesn't help most people much when trying to picture how large a lot is. Half acre lot is roughly:
Each acre is 43,560 square f â¦ eet   Therefore, one quarter of a section is 640/4 x 43,560 = 6,969,600 square feet.   Alternatively, you can see that a square mile cut into quarters would be 4 half-mile by half-mile squares. A mile is 5,280 feet, so each square would be (1/2 x 5,280)2 = 6,969,600 square feet.