The Mitchell phonograph was manufactured by the Dominion Organ & Piano Co., Limited, Bowmanville, Ontario. It was announced to the public in July, 1922.
Canadian Music Trades Journal, January 1918, p. 63: "Bowmanville's mayor for 1918 is Mr. J. B. Mitchell, of the Dominion Piano and Organ Co. Ltd.". Mitchell was the superintendent of the Dominion factories. This important individual likely had a hand in coming up with the name "Mitchell" for their phonograph.
From Betty Pratt: "There were Letters Patent incorporating the Dominion Organ Company on Dec. 15 1873. The factory and warerooms were on the corner of Temperance and Wellington St., Bowmanville. However there was some reorganization before 1873 due to the Clough & Warren Organ Company of Detroit Michigan. Simmons & Clough advertised in the Bowmanville newspaper, the Canadian Statesman, between 1872 and 1876. Jessie Farwell of Simmons & Clough was linked to Darley and Robinson Melodeon Company in Oshawa. Then, he also continued as President of Dominion in Bowmanville. In 1876 the firm was re-organized by men of Clough & Warren of Detroit including Farwell, Wesley, Piggott, and Russell. A piano factory was added 1879, there was a charter for Dominion Organ and Piano Co. in 1880, and in 1886 "Ltd" was added to the name. Pipe organs were also made. The company wound up in 1937."
Three links include more information on Dominion, Bowmanville:
https://harmonium.forumactif.org/t1989-orchestral-reed-organ-dominion
https://antiquepianoshop.com/clough-warren/
https://www.pumporganrestorations.com/dominion_organ_company.htm
The Globe, August 31, 1921, p. 17. The Mitchell Patent Phonograph makes its first public appearance at the Canadian National Exhibition in Toronto.
The Globe, July 24, 1922, p. 2.
The Globe, August 21, 1922, p. 12.
The Globe, August 31, 1922, p. 8.
The Globe, September 18, 1922, p. 10.
The Globe, October 2, 1922, p. 5.
Winnipeg Free Press Evening Bulletin, November 23, 1922, p. 16.
Calgary Herald, April 14, 1923, p. 11.
Calgary Albertan, July 12, 1923, p. 2.
Bowmanville Museum curator, Dan Hoffman, poses with a Mitchell portable phonograph manufactured by the town's former Dominion Organ and Piano Company, August 17, 1988.
Steve Redman submits this Mitchell phonograph for sale on FB Marketplace, February, 2023, sadly painted white! The nameplate identifies the manufacturer as The Mitchell Talking Machine Company, Bowmanville, Ontario.
