Instead, however, of launching to the public gaze a vessel on a large scale fitted with his plans, he made a model boat of about 20 inches in length, into which he placed a small engine, and floated her in a large bath over which a steam boiler had been fitted for the supply of hot water. From this boiler a pipe projected to within a foot of the water, where it was branched off by a swivel joint and connected with the engine in the boat. The steam when admitted put the engine in motion, and also the propeller, which at once sent the boat forward with considerable rapidity.
The Francis B. Ogden, though successful, fails to convince the Admiralty.
Finding that his invention was likely to succeed when put into practical operation on a larger scale, Ericsson’s next step was to order Mr. Gulliver, a boat-builder at Wapping, to construct for him a boat of wood which he named the Francis B. Ogden. She was 45 feet long and 8 feet wide, drawing 2 feet 3 inches of water. In this vessel he fitted his engine and two propellers, each of 5 feet 3 inches diameter. The result of her first trial went far beyond his most sanguine expectations. No sooner were the engines put at full speed, than she shot ahead at the rate of more than 10 miles an hour, and maintained that speed without a single alteration requiring to be made in her machinery;[137] nor were her capabilities as a tug less surprising. This miniature steamer, tested first by a schooner of 140 tons burden, towed her at the rate of 7 miles an hour during slack water on the Thames; and afterwards by the large American packet-ship Toronto, moving on with her astern at a speed of more than 5 miles an hour. The next experiment was made in the presence of the Lords of the Admiralty, who, accompanied by Sir William Symonds, Sir Edward Parry, and Captain Beaufort, had embarked in their barge to witness the novelty, and judge for themselves as to its efficiency and practical value. They were minute in their inspection, and as they did not, and in fact could not, offer any valid objections to his invention, Captain Ericsson felt confident that they would soon order the construction of a war-steamer on the new principle. In this, however, he was disappointed, though he had given them a very practical proof of its value by towing them in their barge at the rate of 10 miles an hour for a considerable distance—a speed which must have astonished their Lordships. The unseen and comparatively noiseless propeller, although it had furnished the most convincing proofs of its power, failed to propitiate their favour. Scientific theorists had informed the Board that the invention was constructed upon erroneous principles, and full of practical defects (one being that a ship thus propelled would be unsteerable), while engineers as a body regarded its failure as an event so certain as to preclude any speculations of its success. In a word, when publicly discussed, the general opinion was that the vast loss of mechanical power would prevent it from being employed as a substitute for the now old-fashioned paddle-wheel![138]
Mr. T. P. Smith.
While Ericsson was making his experiments in the Francis B. Ogden, Mr. Thomas Pettit Smith, who, on the 31st of May, 1836, had taken out a patent for a “sort of screw or ‘worm,’ made to revolve rapidly under water in a recess or open space formed in that part of the after part of the vessel commonly called the dead rising or dead wood of the stern,”[139] was also at work with his invention, and, in the following year, put it into practical operation. His first trial, made in a small vessel of 6 tons burden, with an engine the cylinder of which was 6 inches diameter and 15 inches stroke, was considered by a few far-seeing persons so satisfactory,[140] that they applied for, and obtained on the 29th of July, 1839, an Act of Parliament for incorporating a company called the Steam Ship Propeller Company, to enable them to purchase “certain letters patent,” that is, the screw-propeller of T. P. Smith.
The Archimedes.
Her trial with the Widgeon, Oct. 1839,
The first successful application of this screw-propeller, on a large scale, was to a vessel called the Archimedes, constructed under the direction of the patentee of the screw, Mr. Smith. Her burden was 237 tons, and her mean draught of water 9 feet 4 inches; the diameter of the cylinder 37 inches, and the length of the stroke of the piston 3 feet; her screw-propeller consisted of two half threads of an 8 feet pitch, 5 feet 9 inches in diameter; each was 4 feet in length, and they were placed diametrically opposite to each other, at an angle of about 45 degrees on the propeller shaft. The propeller itself passed through a hole cut in the dead wood, immediately before the rudder; the keel being continued under the screw. The performance of the engines averaged twenty-six strokes per minute, the revolutions of the screw at the same time being 138⅖. The calculations of the inventor were that, provided there was no slip or recession, the vessel ought to advance 8 feet for every revolution of the screw, or 12·60 miles per hour. But the utmost speed ever obtained by the Archimedes, under the power of steam alone, was 9·25 nautical miles per hour, showing a loss by recession of rather less than one-sixth under the most favourable circumstances. The Archimedes was not, however, a fair illustration of the screw-propelling principle, as her steam-power was not great enough to drive a screw sufficient for the size of the vessel. Nevertheless, in her subsequent trials from Dover to Calais against the Widgeon, the fastest paddle-steamer on the station, the superior value of the screw-propeller was proved. Although in the first three or four experiments the Widgeon had the advantage by a few minutes, in the subsequent trials, both vessels having set the whole of their sails, the Archimedes, carrying much more canvas than the Widgeon, on a run of 26 miles from Dover to Calais, close hauled, accomplished this distance in nine minutes less time than the Widgeon. Upon the return voyage to Dover, with a fresh breeze abeam and all sail set, the Archimedes, with a speed of ten knots per hour, performed the distance in five and a half minutes less time than the Widgeon.
and its results.
These experiments decided the practical value of the screw. They proved that the Archimedes was slightly inferior to the Widgeon in light airs, in calms, and in smooth water; but, as the steam power of the former was ten horses less, and her burthen 75 tons more than that of the Widgeon, it is evident that in such vessels the propelling power of the screw alone was equal, if not superior, to the ordinary paddle-wheel. In this respect, therefore, Mr. T. P. Smith’s invention might be considered completely successful. It was evident from the second trial that, in steaming against even a light wind, the low masts and snug rig of the Widgeon gave her an advantage over the Archimedes with loftier masts and heavier rig; but, on the last two trials, the power of the sails operated favourably for the Archimedes, as she then beat the Widgeon, and made the passage between Dover and Calais in less time than it had ever previously been performed by any of Her Majesty’s mail packets. On this occasion the Archimedes went from Dover to Calais in two hours and one minute, and returned in one hour and fifty-three and a half minutes.[141]