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:
An acre is a measure of area. An acre is equal to 43,560 square feet. So a half acre is equal to 21,780 squre feet. If you are looking at houses, a 100 ft wide and 200 ft deep lot (pretty common for new houses in areas that do not have very high housing prices) is 20,000 square feet and just under 1/2 an acre. Source(s):