He was a careful investor and financial manager, and at his death in 1903 his estate was valued at $100,000 (roughly $ today). For many years, he served as trustee, secretary, and treasurer of his alma mater, the Hopkins School. US President Chester A. Arthur appointed him as one of the commissioners to the National Conference of Electricians, which convened in Philadelphia in September 1884, and Gibbs presided over one of its sessions. A keen and skilled horseman, Gibbs was seen habitually in New Haven driving his sister's carriage. In an obituary published in the "American Journal of Science", Gibbs's former student Henry A. Bumstead referred to Gibbs's personal character: