In 1880, he was appointed General Manager of the Canadian Pacific Railway Telegraph Service, retiring to turn his attentions to various other business opportunities.

[1] He was President of Canadian Cottons Ltd. and the Ogilvie Flour Mills Company.

Hosmer was known for his liveliness and wit, becoming a close friend of both Edward VII and César Ritz.

His home on Upper Drummond Street in Montreal's Golden Square Mile was to some a suitable showcase of his wealth, while to others it was viewed as pretentious.

His son, Elwood Bigelow Hosmer (1879-1947) made an attempt to fly across the Atlantic Ocean in 1927, surviving after coming down near the Azores.