Boulton's Soho site proved to have insufficient hydropower for his needs, especially in the summer when the millstream's flow was greatly reduced. He realised that using a steam engine either to pump water back up to the millpond or to drive equipment directly would help to provide the necessary power. He began to correspond with Watt in 1766, and first met him two years later. In 1769 Watt patented an engine with the innovation of a separate condenser, making it far more efficient than earlier engines. Boulton realised not only that this engine could power his manufactory, but also that its production might be a profitable business venture.