He was educated in the public schools in Sheboygan Falls, and then attended Bryant, Stratton, & Spencer Commercial College in Milwaukee, Wisconsin.
[1] After school, he went to Beloit, Wisconsin, where he was employed by Proctor & Stone, reaper manufacturers, and later became secretary of the company.
He defeated Democrat James Leahy, receiving 60% of the vote in the general election and winning a four-year term.
[8] In 1909, Dennett, along with the other commissioners, Otto B. Joerns and then-mayor Theodore Dieckmann, voted to extend the water plant's intake pipe deeper into Lake Michigan to get purer water—at the time, it was believed that the poor condition of the plant under private management had led to a spread of Typhoid in the city.
Dieckmann's side pointed to roughly $100,000 in profits the waterworks had accumulated (about $3.3M adjusted for inflation), and suggested the money could be redistributed to the city's population.
The belligerence dragged on for another two years and involved the state legislature in an effort to clarify the legal status of the waterworks.
Dennett later announced that he planned to close his Manitowoc factory, then one of the largest employers in the city, and move the manufacturing business to Buffalo, New York.
[13] In January 1906, however, a catastrophic fire swept through the factory, destroying the building and a large supply of finished product; a firefighters was killed by falling debris.
[14] Because of confusion over the terms of the sale of the building and the lease of the facility back to Wisconsin Chair, a lawsuit ensued over insurance claims by the two companies.
Dennett died of a heart attack in Grafton, Wisconsin, on May 11, 1920, while visiting his New York Recording Laboratories business in that village.
His maternal grandfather, Richard Gale Jr., served for two years in the Massachusetts militia during the American Revolutionary War.