The next week commenced with a trial of speed between the Rattler and the Polyphemus, or screw v. paddle wheel. On this occasion Sir William Parker invited the captains of the different ships to assemble to witness the trial ; but refused permission to several officers who wished to be present. The steam vessels, in order to test the relative amount of their propelling power, were, by the Admiral's order, secure stern to stern by two stout hawsers, which left them when the hawsers were at full stretch, about fifteen or twenty yards apart. By the time the experiment commenced, it had fallen quite calm, consequently there could not have been a better opportunity for testing their rival powers. If anything, the advantage was on the side of the Polyphemus, as the Rattler had a slight westerly swell to overcome. The engines of both vessels are of the same nominal power ; viz., 200 horse, but in tons, the Rattler exceeds the Polyphemus by 80.

This of course gave the former a greater body to propel ; but a must also be remembered that the Rattler has greater length, and consequently a better form of body for speed. The Polyphemus, with her head to the eastward, struggled hard for the mastery ; her paddles lashed the water into foam, and afforded a vivid contrast in appearance to the quiet, but dogged strength of the Rattler. For a long time the victory remained in abeyance. The burr of the sub-marine propeller afforded evidence to the ear that there was a powerful agent assisting the Rattler; while the loud dash of the paddle gave outward sign that the steam of her antagonist was doing its work. At length the waste safety-valve of the Polyphemus began to emit steam in greater volumes than it had previously, and the revolutions of the wheels to diminish in number, while, on the other hand, the Rattler's waste steam wholly disappeared, and now and then a bright flash from under her quarter, evinced increased activity beneath, and the ripples under the stern of the Polyphemus began to show themselves plainly. The Rattler had won the day, and the luckless Polyphemus was dragged astern at the rate of a knot or a knot and a half an hour, an unwilling spectacle of her rival's greater strength. It was a great day for Archimedes ; but the Admiral decided that another test should be tried, and their resistive power, when reversed, be proved. The hawsers were accordingly carried forward, and the vessels were secured, with their bows nearly touching each other, but the result was the same. The screw was in the ascendancy, even at its worst point ; and it therefore only remains to remedy certain working difficulties in order to render this invention still more important. After the conclusion of this highly interesting trial, the two ships were ordered to try their rate of steaming for eighteen miles to, the eastward, and in this trial the screw had again an advantage, the Rattler beating her competitor 3,660 yards in little more than two hours.-United Services Gazette.

SG & SGTL ; Vol 4 ; Page 19

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