Apothecary and patron of natural sciences, he interested some young men who visited his shop on 2nd and Market Streets, in founding the Academy of Natural Sciences in 1812. This apothecary shop has been referred to as, “a center of literary and scientific gossip.” Speakman's abilities were in administrative rather than in the scientific aspects of the new venture. He acted as chairman of the preliminary meeting and later became the Academy's first treasurer, its first librarian and its first auditor.

His only scientific communication known to have been made to the Academy members was delivered on Jan. 21, 1845, and was referred to by Speakman as, “My views on the Operation of Nature.” It was primarily a criticism of Joseph Black's opinion on light and his two kinds of heat. The Committee on Publications rejected the paper, only to have Speakman come back to the subject again and again. Finally at a meeting, March 4, 1845, the members voted to file the various communications in the Academy's archives. These papers, plus correspondence regarding his place of burial, make up this collection. Speakman's last attendance at an Academy meeting was April 2, 1845.