In 1824 it was claimed that he had made about 100 engines in England and another 200 in France, but this is probably an exaggeration. He became a member of the firm Scipion, Perrier, Edwards \& Chappert, which took over the Chaillot Foundry of the Perrier Frères in Paris, and it seems that Edwards continued to build steam engines there for the rest of his life. Edwards may have formed a partnership with Goupil \& Cie, Dampierre, to build engines, but this is uncertain. In France there was always much more interest in rotative engines than pumping ones. He licensed a mining company in the north of France to make twenty-five engines for winding coal. A report in 1817 shows that during the previous two years he had imported into France fifteen engines of different sizes which were at work in eight places in various parts of the country. On he obtained a French patent, a Brevet d'importation, for ten years. Edwards struggled on alone in London for a while, but when he saw a more promising future for the engine in France he moved to Paris. Woolf visited Cornwall, where he realized that more potential for his engines lay there than in London in May 1811 the partnership was dissolved, with Woolf returning to his home county. In an advertisement of February 1811, the partners claimed that their engines had been brought to such a state of perfection that they consumed only half the quantity of coal required for engines on the plan of Messrs Boulton \& Watt. Steam pressure may have been around 40 psi (2.8 kg/cm 2). The valve gear and other details were also improved.
During this experimental period, engines were made with cylinders side by side as well as the more usual layout with one behind the other. Improvements were made in each succeeding engine, and by 1811 a standard form had been evolved. A number of small engines were constructed and other ordinary engines modified with the addition of a high-pressure cylinder.
When Arthur Woolf left the Griffin Brewery, London, in October 1808, he formed a partnership with Humphrey Edwards, described as a millwright at Mill Street, Lambeth, where they started an engine works to build Woolf's type of compound engine.