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:
The number of square feet in an acre is 16.5 feet times 2640 feet, which equals 43,560 square feet per acre. There are 144 square inches in a square foot. The number of square inches per acre is 43,560 square feet times 144 square inches, which equals 6,272,640 square inches per acre.