His continued activity distressed Watt, who had entirely retired from Soho, and who wrote to Boulton in 1804, "our friends fear much that your necessary attention to the operation of the coinage may injure your health".
Hans fortsatte aktivitet bekymrede Watt, som helt havde trukket sig tilbage fra Soho, og som skrev til Boulton i 1804, "Dine venner er meget bange for at den opmærksomhed du må give driften af mønten kan gå ud over dit helbred".