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:
Since medieval times the acre hasn't had any set dimensions. It is purely an area of 43,560 square feet. The two sides of a 1-acre rectangular lot can be any lengths as long as multiplying one by the other gives 43,560 (if they are measured in feet). For example, imagine a sidewalk 5 feet wide. If it were (43560 Ã· 5 = ) 8712 feet long it would take up an acre, a long skinny acre. On the other hand, if the 1-acre lot were a square, its sides would be only 208.7 feet.