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:
One acre is 43,560 square feet. A square with an area of 43,560 square feet would have side length the square root of 43,560, that is approxiamtely 208.7 feet. Thus a square plot of land with sides of length 208.7 feet has an area of one acre. Penny.