Steamships and their story

by E. Keble Chatterton

From the Original in the possession of the New Jersey Historical Society.

Before leaving England in 1806, Fulton had already made a set of drawings embodying his ideas with regard to the forthcoming Clermont. And so zealous was he for their safety, that before leaving by the October Falmouth packet he had these carefully placed in a tin cylinder, sealed and left in the care of a General Lyman, with instructions that it was not to be opened unless he went down during the crossing of the Atlantic. But if he reached America safely these were to be sent across to him in one of the vessels leaving about the following April, “when the risk will be inconsiderable.” [The illustration on page 64] represents “Plate the First,” giving Fulton’s design of an apparatus for finding the resistance of paddles for the propulsion of the Clermont. In this he demonstrated the impropriety of making small paddles for a large boat. Briefly we may explain it by remarking that Fulton was proving that the paddles in the water should present, if possible, more surface than the bow of the boat, and that careful calculation must be reckoned so as to avoid wastage of power by not making due allowance for the resistance of the ship as she goes through the water. In Fulton’s time the relation of the water to the moving ship had not been accurately defined, and for that matter has not been finally settled to-day, although, thanks to the patient and valuable experiments of the late Scott Russell, W. Froude and of his son, Dr. Robert Edmund Froude, we have now considerable knowledge on the subject, which has borne practical fruit in the design of the hulls of modern ships. To-day experiments are still going on in specially-fitted tanks in different parts of England, America and Germany. At the moment of writing a special launch is being built at Marblehead, U.S.A., for purely experimental purposes under the direction of Professor Peabody, since the conditions which prevail in tanks using small models are not thought to be wholly trustworthy. The problems to be considered will embrace the number of propellers which give the best speed; they will be tried in all sorts of positions, and an endeavour will be made to ascertain the relation of the resistance of the boat to the force generated by the engines inside, and the effectiveness which the combination of hull and boat produce. Every motor-boat owner to-day knows very well that there is a good deal of difference sometimes between the calculations of the theorist in regard to the propeller and the knowledge which comes by actual use.

Many of the readers of this volume will no doubt have often been struck by the enormous rate of speed which a porpoise exhibits as he goes through the water. Those who spend their time crossing the ocean are familiar with the sight of these creatures saucily playing about the bows of a fast liner as she goes tearing through the water. It has been calculated that it would require no less than 15 horse-power to obtain the twenty miles an hour at which these animals can travel for long periods at a time. The explanation is that in their skins there is a wonderful system of glands, which exude oil and so minimise the influence of skin-friction. Remembering this, mechanical attempts have even been made quite recently to obtain a steel plate which would allow the oil to exude under pressure from the inside of the vessel’s bows.

Possibly, nowadays, every engineer has his own formula for determining the amount of horse-power essential for a given speed. All sorts of sliding scales and devices have been invented for this purpose, and the ideal shape of the modern propeller has still to be ascertained. It is a well-known fact that when a vessel moves through the sea she sets the water itself in motion, so that some of it actually travels with the ship; but Naval Constructor D. W. Taylor, of the United States Navy, found by experiment in 1908 that when a ship progresses the flow of the water is down forward, and then it passes under the ship, coming up again aft. Practically we can sum up the resistance which a ship has to encounter under three heads. First of all, there is the skin resistance already mentioned, which, of course, varies with the amount of wetted surface. Then after the ship has passed through the water there ensues an impeding eddy at the stern, as the reader must often have observed. Finally, there is the resistance caused by wave-making, which for vessels propelled at high speeds is an important consideration, but varies according to the design of the ship and her pace.

We have digressed somewhat from our immediate historical continuity, because not merely is it essential to appreciate some of the difficulties which the ship-man of to-day has to encounter, but in order to show that, though Fulton was very far from comprehending all the details of the relations between resistance and hull which recent experiments alone are determining, yet he was working on right lines, and with a certainty of aim that was positively unique for the beginning of the nineteenth century. Reverting, then, to the [illustration on page 64], he explains in his footnote that a nice calculation must be made on the velocities of the wheels which drive the paddle-wheels, whilst the same regard must also be had for the rate at which the paddle-wheels and the boat herself are to move. Thus, he says, supposing a boat is calculated to run at the rate of four miles an hour, the paddles and bow presenting equal surfaces in the water, then the circumference of the wheel must run eight miles an hour, of which four strike water back equal to the water divided by the boat, the other four miles, so to speak, overtaking the boat. But, he adds, if the paddles were made twice as large the engine would stand still. In the illustration, much of which has necessarily suffered through having to be reduced, we see an arrangement of pulleys and lines, and a weight. To the left of the diagram, A represents the boat which is to be propelled through the water, while B, shown at the extreme right of the illustration, is the paddle which is to send the ship along. Both present a flat front of four feet to the water. By the known resistance, Fulton argued, each would require twelve pounds to draw each one mile per hour, so that if the pulley and weight marked C weighed 24 pounds, and descended to where it is marked “No. 1,” then the boat A would be drawn to the point marked 2 (seen just to the right of it) and the paddle would be drawn to that spot marked 3, each moving through equal spaces in equal times, twelve of the 24 pounds being consumed by the boat and twelve by the paddles. Thus half of the power is actually consumed by the paddles. Next, he says, suppose that the flat front of the paddle is reduced to one foot while the boat still remains four. “The paddle being one-fourth the size of the boat must move 2 miles an hour to create a resistance for the boat to move one mile in the same time.” Finally, as we said, he concludes that the paddles acting in the water should, if possible, present more surface than the bow of the boat, and power will thus be saved.

Practically no part of the Clermont was an invention of Fulton: it was the manner of employing these parts scientifically that brought him his success. He was able, too, to distribute his weights so well that not only was the wooden hull able to sustain them, but the vessel floated on an even keel and was not inflicted with a list either one side or the other. To have done this in those early days of steamship building was rather more important an achievement than the average reader may imagine, but any naval architect and shipbuilder will readily grant it. The Clermont’s boiler was set in masonry, while her condenser stood in a large cold-water cistern. Fulton threw the whole of his enthusiasm into his work, and when, in the early part of the year 1807, he was invited by the President of the United States to examine the ground and report on the possibility of making a canal to join the Mississippi and Lake Pontchartrain, the inventor, writing on the 20th of March, had to decline the invitation for, says he, “I have now Ship Builders, Blacksmiths and Carpenters occupied at New York in building and executing the machinery of my Steam Boat.”

THE RECONSTRUCTED “CLERMONT” AT THE HUDSON-FULTON CELEBRATIONS, 1909.

Photographs: Topical.