In the meantime Savery in England had produced his successful engine. In his case, too, the claim has been made that he first proposed steam propulsion for ships. But in his _Miner’s Friend_ this able mechanician showed that he recognized the limited application of his steam engine. “I believe,” he says, “it may be made very _useful_ to ships, but I dare not meddle with that matter; and leave it to the judgment of those who are the best judges of maritime affairs.” But in propulsion by hand-operated paddlewheels Savery was an enthusiastic believer. In 1698 he had published, in a book bearing the title, “_Navigation Improv’d: Or the Art of Rowing Ships of all Rates, in Calms, with a more easy, swift, and steady Motion than Oars can_,” a description of a mechanism consisting of paddlewheels formed of oars fitted radially to drumheads which were mounted on the two ends of an iron bar placed horizontally across the ship. This bar was geared by mortice wheels with another bar mounted vertically as the axis of a capstan; rotation of the capstan was thus transmitted to the paddlewheels. Savery fitted this mechanism to a wherry and carried out successful trials on the Thames before thousands of people. But the Navy Board would not consider it. They had incurred a loss, it appeared, on a horse tow-vessel which had been in use at Chatham a few years previously: a vessel which towed the greatest ships with the help of four, six, or eight horses, and which, incidentally, may have influenced Savery in adopting the term “horse power” as the unit of work for his steam engine. The sanguine inventor made great efforts to interest the authorities, but without avail; the Surveyor rejected the proposal. So in an angry mood Savery published his book, with a description of his mechanism and an account of his efforts to interest the authorities, to show how one man’s humour had obstructed his engine. “You see, Reader, what to trust to,” he concluded, “though you have found out an improvement as great to shipping as turning to windward, or the compass; unless you can sit round the green table in Crutched Friars, your invention is damned of course.”