Fig. 11 Propeller Hub with Adjustable Blades, of 1804
These are now on exhibition at Chicago, and are shown in Fig. 11.
This hub and blade were brought into the District Court of New York at the April term in 1844, at the request of the counsel of Ericsson and of Hogg & Delamater, in the suit of J. B. Emerson of New Orleans, for the infringement of his patent in manufacturing the Ericsson propeller; and it was fully identified, as a portion of a screw propeller used on the Hudson River, by John Stevens. In this suit, Emerson claimed that his patent covered the form of Ericsson's propeller; and he also broadly claimed the use of the screw propeller. The evidence of the earlier use by Stevens of the blade exhibited in court, was perfect ; and Emerson's broad claim was disallowed. The jury, however, awarded him damages for the infringement of the form of his screw propeller. The case was carried, on appeal, to the Circuit Court in 1847; and decided in the favor of Emerson by the Supreme Court at Washington in 1850.
This propeller blade, is made in accordance with the description given in the letter to Doctor Hare. The broken shank on the hub shows this propeller to have been, when last used, the short two bladed screw propeller of the present day, with the blades separately attached; and the two other opposite holes in the hub show that it was made to be also used as a four-bladed propeller. The blades, are shown attached to the hub by a round bar or shank fitting into a corresponding hole in the hub, and with its axis perpendicular to that of the propeller shaft; so that the pitch can be adjusted by slightly turning the bar or shank in the hub. In his letter to Doctor Hare, Colonel Stevens says "These blades are made capable of ready adjustment, so that the most advantageous obliquity of their angle may be attained."
This method of adjustment is identical in principle with that of Griffiths', whose propeller, the automatic machinery for adjustment being omitted, is shown by Fig. 12.
Griffiths' plan for carrying into effect this method of adjustment is excellent. He first proved that by making the hub globular or partially globular it could be enlarged without detriment, to a
Fig. 12 Griffiths' Screw Propeller.
Traced from his patent Specification No. 12769. A. D. 1849, September 13.
certain extent, beyond the size previously used; and, after he had discarded his automatic machinery, he utilized the hub, then only partially enlarged, for the attachment of his blades to it, by forming a flange with a plane surface at the base of each blade, and by bolting this flange to a corresponding surface made on the hub. The adjustment of the pitch is made, at the present day, by slightly altering the bolt holes of the flange.
The improvement of Griffiths, is regarded by the writer as the greatest made on the form of the screw propeller since 1804.
James Alexander Stevens, who was the third son of Colonel Stevens, and who was 16 years of age at the commencement of the year 1806, has described this boat as being about 50 feet long, and as drawing about 4 feet of water, and has stated that he was on it when it made several trial trips up the Hudson River. In this he was corroborated in a letter from his uncle-in-law, Horace Emney of Philadelphia, to whom he wrote in 1871, asking him if he remembered taking a trip on this vessel in 1805-6. Mr. Binney replied that he recollected it perfectly; mentioning that, on the return of the boat to the cove above Hoboken, some difficulty occurred in landing, on account of the draught of water of the boat. This boat is described in the letter of John Stevens to Doctor Hare as a twin-screw vessel, then nearly completed. As it was a much larger vessel than the others, the defects of the machinery would have been much more manifest.
John Stevens patented his multi-tubular boiler in this country on the 26th. of August, 1791, and the 11th. of August, 1803, and in England, May 31, 1805. In addition to the boiler exhibited, two more are described in Stuart's publication previously mentioned one having 81 tubes each 1 inch in diameter, and the other having about 765 horizontal tubes each 1 inch in diameter and 2 feet long, placed between two tube sheets of cast brass, each sheet being 4x6 feet, the tubes being spaced 2 inches from center to center. The tube surface was 400 square feet. Another form of his boiler, with vertical iron tubes, that operated an experimental locomotive at Hoboken in 1825, is still preserved.
The English patent, of 1805, was taken out by John Cox Stevens, then a very young man, who described the Subject of the patent, the multi-tubular boiler, as "an invention communicated to him by his father."
It was he whom Dr. Renwick recognized as coxswain of the "queer sort of a boat" at the Battery in May, 1804. In after years, he was the founder and first Commodore of the New York Yacht Club, and commanded the yacht "America" in her famous race off the Isle of Wight in 1851. When in England in 1805 he went to Heathfield, the seat of Watt, who had then retired from business, and presented a letter from his father. Watt received him kindly but reiterated his well-known objections to the use of steam at a pressure over two or three pounds above the atmosphere.
These boilers of Colonel Stevens have often been referred to in relation to the introduction of the multi-tubular boiler on locomotives.
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