He was well connected and active in numerous organizations in Yokohama, including the Committee of the Yokohama General Hospital, the Club Germania, the German-Evangelical Church of Yokohama, and the British Yokohama United Club. Coming back to Switzerland in his later years, he settled down and soon passed away in his native Frauenfeld, seven years after his homecoming.
The project centers on the life, career, and collections of Dumelin. Important among these documents are the copies of letters written as the Swiss Consul-General in 1890-92, a rare and fortuitous case when a sizable amount of consular correspondence from early Swiss consulates has been preserved.