c. 1920 Dempster Mill Class H 2 1/2 HP Engine

 This engine (serial #11542) was built by the Dempster Mill Manufacturing Company located in Beatrice, Nebraska, about 120 miles east-southeast of Grand Island. Established in 1878 and incorporated in 1886, Dempster Mill became a major windmill and pump manufacturer by the turn of the 20th century. In 1902, the company added two-cycle engines to its product lines; however, in 1909, it had switched to four-cycle engines.

 If you look at the side of this engine, you might see that it has a Webster Type K Tri-Polar Oscillator, made in Racine, Wisconsin. If you're interested in how magnetos work, an informative article on magnetos, including the Webster Tri-Polar Oscillator, can be found here.  This engine also has an American Injector Company lubricator, made in Detroit, Michigan.

From Farm Implement News:
The Tractor and Truck Review,
vol. XL, no. 1 (January 2, 1919), p. 66.