The Archimedes next circumnavigated Great Britain under command of Captain Chappel, visiting all the principal ports: she afterwards went to Oporto, Antwerp, and other places, and everywhere excited the admiration of engineers and seamen.
Up to this period, the British engineers were nearly unanimous in the opinion that the use of the screw involved a great loss of power, and they had concluded that it could not be adopted; but it was impossible any longer to resist the impressions made on the public by the demonstration which had been given both by Smith and Ericsson; and although the engineers were still unwilling to admit the screw to a comparison with the paddle, it was evident that their first conclusions regarding it were erroneous, and thereafter it was viewed by them with less disdain and spoken of more hopefully. One of the great objections by engineers to the use of the screw was their inability, at the time of its introduction, to construct properly a screw engine,—that is to say, a direct-acting horizontal engine, working at a speed of from sixty to one hundred revolutions per minute,—all their experience having been in paddle-wheel engines, working from ten to fifteen revolutions per minute. The peculiar mechanical details required in the screw engine, the necessity for accurate counterbalancing, etc., were then unknown, and had to be learned from a long succession of expensive failures. In England, the first machines applied to the screw were paddle-wheel engines, working it by gearing; there were consequently lost all the advantages of the reduced cost, bulk, and weight of the screw engine proper, including, for war purposes, the important feature of its being placed below the water-line. At first, the screw had not only to contend with physical difficulties, but to struggle against nearly universal prejudice; many inventors had succumbed to these obstacles, and therefore too much applause cannot be bestowed upon those who, unsustained by public sympathy, and in defiance of a prevailing skepticism, maintained their faith and courage unshaken, and gallantly persisted in their efforts, until crowned with a world-wide success.
Ericsson, before interesting himself with the screw, was, as has been seen, an engineer and mechanician of distinguished ability; whereas Smith, in commencing his new vocation, had all to acquire but his first conception. Ericsson could rely upon the fertility of his own genius, was his own draughtsman, and designed his own engines, accommodating them to the new propeller by dispensing with gearing, and adapting them to a speed of from thirty to forty revolutions,—a great and bold advance for an initiative step. Smith, on the contrary, not being an engineer, had to intrust the execution of his plans to others, whose knowledge of construction was in the routine of paddle-wheel engines; and this accounts for the fact, that all the earliest British screw-steamers were driven by gearing. This want of mechanical resources on the part of Smith added to the difficulties of his career; but his resolution and perseverance rose superior to all obstacles, and carried him to the goal in triumph. Briefly, then, these were the respective merits of Smith and Ericsson, in the introduction of screw-propulsion; and it is much to their honor, that, throughout their career, no narrow-spirited jealousies dimmed the lustre of a noble rivalry.
Such was the origin of the new motor,—the mighty engine by which armadas are marshalled in battle-array, the burdens of commerce borne to distant marts, the impatient emigrant transferred to the promised land, and by which the breathings of affection, the pangs of distress, and the sighs of love are wafted to far-off continents.
In consequence of the success of the Archimedes, the Admiralty ordered the Rattler to be fitted with a screw, and it was no small satisfaction to find that her double-cylinder engines could be easily adapted to the new propeller. She is of 888 tons, and two hundred horse-power, and was launched in the spring of 1843, being the first screw-vessel in the British navy.
In the course of the two succeeding years, she was tried with a great many different screws, and numerous experiments were made to discover the length, diameter, pitch, and number of blades of the screw, most effective in all the various conditions of wind and sea. A screw of two blades, each equal to one-sixth part of a convolution, and of a uniform pitch, was, on the whole, found to be the most efficient, and this is the screw now adopted in most of the ships of all classes in the British navy.[1]
A propeller of very different construction, which had given great results in a ship of the Peninsular and Oriental Steamship Company, and was afterwards exhibited in the docks at Southampton, here claims a passing notice. This propeller is so constructed as to enable the engineer to regulate the speed of the piston; for the pitch of the screw can be increased or diminished at pleasure. Thus, with a fair wind, by increasing the pitch, without increasing the revolutions, the full power of the engine is effectually exerted in driving the ship, instead of consuming fuel in driving the engine to no purpose; and with a headwind, by diminishing the pitch, the engines are made to do their utmost duty; and when the ship is under canvas only, the blades of the propeller may be placed in line with the stern-post, and thus offer little resistance. Another advantage claimed for this propeller (known as Griffith's) is, that, in the event of breaking a blade, it may be readily replaced by "tipping the ship"; which method merits careful consideration by engineers, as does especially every new propeller which promises a more perfect alliance with canvas.
To resume the narrative,—the speed of the Rattler was afterwards tested by a trial with the Alecto, a paddle-wheel steamer of equal power, built from the same moulds; and the result was so favorable, that the Admiralty ordered the construction or conversion of twenty-three vessels as screw-steamers, and thus was laid the foundation of the present formidable steam-navy of England.
The superiority which has been asserted for the Princeton was established during the Mexican War by her performance before Vera Cruz as a blockading ship of unprecedented efficiency, which, having been displayed under the admiring observation of a British squadron, tended more than any other single event to confirm the Admiralty in the conclusions to be drawn from the experiments just related, and to decide them in the adoption of the screw as the best auxiliary of sail, the best mechanical motor upon the ocean. Thus did England, in embracing at once the practical demonstration of the Princeton, display that forecast by which she won her ascendency at sea, and the vigilance with which she maintains it; whilst our own government awaited, in unbecoming hesitation, the results which England's more extended trials with the screw might develop.
This cautious policy, rather than the bold and liberal course which the maritime genius of the country demands, condemned us for long years to inaction, until, at length, the absolute necessity for the renewal of a portion of our naval force produced the "Minnesota" class of frigates. Although they developed little that was absolutely new, they are very far from being imitations; but in model, capacity, equipment, and above all in their armament, they have challenged admiration throughout the world, and called from a distinguished British admiral in command the significant declaration, that, until he had seen them, he had never realized his ideal of a perfect man-of-war.