We have now traced the evolution of the steam engine up to the time when it was first adapted to the propulsion of war-vessels. There we must leave it. In a later chapter we shall consider the evolution of the propelling machinery in its relation, especially, to the military qualities of ships. A few observations will be sufficient to illustrate the conditions, as to design, practice, and material, under which the steam engine made its appearance in the royal navy.
After the death of Watt all improvement of steam machinery was strenuously opposed by the combined force of prejudice and vested interest. The great Watt himself had set his face against the use of high-pressure steam, and, such was the lingering force of his authority, years passed before the general public gave assent to the advances made by his talented successors—Hornblower, Woolf, Evans, and Trevithick. Before the end of the eighteenth century the first steps had been made to use the force of steam for driving ships. Before Trafalgar was fought steam engines had made their appearance in the royal dockyards. Then there was a pause; and many years passed by before steam propulsion was admitted to be a necessity for certain classes of war-vessels.
An interesting account of the state of design and practice as it existed on ship-board in the year of Queen Victoria’s accession is given by Commander Robert Otway, R.N., in his treatise on Steam Navigation. Low-pressure principles are still in vogue; steam is generated still, at a pressure not exceeding three pounds per square inch, in rectangular boilers of various forms according to the fancy of the maker, scarcely two being alike. The engines are also of varying forms, every size, variety, and power being deemed suitable for similar vessels. They are amazingly ponderous: weigh about twelve hundredweight, and the boilers eight hundredweight, to the horsepower. The engines of all makers exhibit the greatest variations in the relative dimensions of their various parts: one firm embodies a massive frame and light moving rods and shafts, another adopts massive rods and shafts, and supports them within the lightest framework. The author advocates a correct design and a “total dispensation of all superfluous ornament.”
CONNECTING ROD
From Otway
Already, however, following the example of the Cornish mines, the builders of steam vessels were at this time beginning to adopt high-pressure steam, generated at a pressure of ten to fifteen pounds per square inch in cylindrical boilers, and working expansively—“doing work in the cylinder by its elasticity alone”—before returning to the jet condenser. This improvement, strenuously opposed by orthodox engineers as being unsafe for ship practice, was introduced first into the Packet Establishment at Falmouth, and then, tardily, into Government steamers. It gave a gain in economy measured by the saving of “thousands of bushels of coal per month.” Steam engines working on the low-pressure system used from nine to twelve pounds of coal per hour, for each horse-power. These engines were carried in vessels “built on the scantling of 10-ton brigs,” of great draught and of such small coal capacity—about 35 tons, on an average—that when proceeding out of home waters “they were burthened with, at the least, four days’ more fuel, on their decks (top hamper), in addition to that which already filled up their coal-boxes below.” Boilers emitted black clouds of smoke at sea. In harbour the paddle-wheels had to be turned daily, if but a few float-boards only, by the united force of the crew. “Coaling ship” was carried out with the help of convicts from the hulks:—“pampered delinquents,” observes the author, “whose very movements are characteristic of their moral dispositions—being thieves of time; for their whole day’s duty is not worth an hour’s purchase.”
In these unattractive circumstances the steam engine, most wonderful contrivance of the brain and hand of man, presented itself for embodiment in the navy, by the personnel of which it was regarded, not without reason, as an unmitigated evil.