by the advancing boat, is influenced by gravity alone, the facility with which the interchange of position between the water and the boat is effected will depend entirely upon the ratio of the sections of the latter and of the prism of the canal; and there will be no difference, in the final result, whether the water passes through the boat, or whether the boat passes through the water, except that, in the former case, the water will move less freely than it will in the latter, on account of the greater wetted permieter and friction of the channel by which such movement is effected. In a word, the adoption of such a device would be equivalent to the adoption of a smaller and more expensive boat than those now in use, and requiring more power for its propulsion.

In the case of the "Port Byron," the effect of the trunk upon the carrying capacity amounts to about 6 tons, causing her to draw nearly two inches more water than she would without the trunk. Had her draft been two inches less, while making her trips east, much of her detention from grounding would have been avoided, and better running time would have been made. The increase in "skinfriction," due to this trunk, is about seventeen per cent.

If the flow of water through the trunk in question is to be accelerated to any considerable extent by the propelling instrument, at the expense of the power of the machinery, the merits of the device become still more questionable, as will appear from the following considerations: The area of a section of the trunk is 2 square feet, and the area of the midship section of the boat, when drawing 6 feet of water, 104 square feet. For our present purpose, we may consider the former as two per cent of the latter. While the loaded boat is advancing a distance equal to its own length, then, a volume of water equal to two per cent of the displacement may be considered as passing through the trunk (in fact the trunk passes through the water). If, now, the boat be inoving at a speed of 3 miles per hour, and ten per cent of the water pass through the trunk, the velocity of the current will be 15 miles per hour, and the equivalent head due to this velocity, together with the resulting friction, will be about 9 feet. In one minute, then, 15 x 88 x 2=2,640 cubic feet of water must pass through the trunk at the expense of sufficient power to raise it to a height of 94 feet. This power will be 47.5 horses, or more than is found necessary to propel the boat, under any circumstances, at the speed named. If 6 per cent of the water be passed through the trunk, or three times as much as would naturally pass, the velocity of the current will be

9 miles per hour, and the frictional head 3.3 feet; while the expenditure of power, on this account, will be 17.4 horses. My observations and estimates satisfy me that this amount of power could not, at any time, have been expended for the purpose indicated, and, hence, that the quantity of water drawn through the trunk could not have amounted to even 6 per cent of the displacement. It is therefore idle to undertake to obviate, by such means, an assumed difficulty which experience and careful observation have shown to have no existence as a matter of fact, or that, if it does exist, its effect is so trifling as not to attract or merit special notice or attention.

The precise effect produced upon the water at the sides of the canal, by the passage of boats, is a depression extending from bow to stern, on each side of the boat, while the normal elevation of the water, both ahead and astern, is not sensibly changed. This depression, which is segmental in profile, advances with the boat. Its greatest depth is at a point nearly opposite to the center of the boat, and varies, with the speed, from an inappreciably small amount, at very low speeds, to a maximum of about nine inches at the highest speeds thus far attained.

The feathering paddle-wheel of the "Port Byron" also requires special attention.

Let it be assumed that it is capable of giving the boat, with 200 tons of cargo, a maximum speed of 3.8 miles per hour through the water, and that the slip of the centers of the paddles, at such speed, is 33 per cent. The wheel will then make 16 revolutions per minute; and the velocity of each paddle, as it reaches its lowest point and greatest efficiency, will be 8.3 feet per second. At the same time the speed of the boat, in the opposite direction, will be 5.57 feet per second. The velocity of the paddle through the water will therefore be 8.3-5.57-2.73 feet per second, which represents its slip. Now, at this instant, the two adjacent buckets, which are 45° distant from the former, will be moving astern at the rate of 8.3 x cos. 45°-5.87 feet per second. Deducting from this the velocity of the boat in the opposite direction, we find that the velocities of each of the two paddles through the water is 5.87-5.57-0.3 of a foot per second. It appears, then, that the forward paddle has just begun to act usefully, and that the after one is just ceasing to act in that manner. efficient action of each paddle is therefore limited to an arc of about 90°.

The

From the instant that each paddle enters the water until it reaches a point about 45° below the horizontal, its motion, astern, is less than

the forward motion of the boat; and hence it is backing water, or retarding the progress of the boat. The same is true of each paddle from the instant it ceases to act efficiently until it leaves the water. Now, each paddle enters the water while its arm is still above the horizontal line passing through the axis of the shaft, and does not leave it until its arm has passed above this line on the after side. Tracing, then, the action of a paddle, from the instant when it enters until it leaves the water, it will be seen that while descending through an arc of about 45° it is backing water or impeding the progress of the boat; that when it passes the point where it ceases to act prejudicially, it begins to act effectively, which action is constantly increased until its lowest point is reached, where the effect is maximum; that beyond this last point the useful effect gradually diminishes, and finally ceases, at a distance of about 45° from the lowest point; and that beyond this point it again becomes an impediment, and continues to be such until it finally leaves the water.

It appears, therefore, that each paddle is effective only during onehalf of its immersion; and that during the other half it is not only inefficient but becomes a serious impediment to the forward movement of the boat.

I have thus pointed out, in a general way, the character of the 'defects of this wheel when deeply immersed, as in the case of the "Port Byron." A careful analysis of its action when the boat is loaded to 6 feet draft, shows that, taking the effect of a paddle at its lowest point as unity, the aggregate useful effect of all the paddles is 1.123, or about 11 paddles. Had the retarding effect, due to back water, been also estimated and deducted, the result would have shown a resultant useful effect for the entire wheel of less than one paddle.

We thus have an explanation of the fact that, on the 18th of November, the mean slip of this wheel was 67 per cent. At 33 per cent slip the effective paddle surface is too small to accomplish the work required of it. In order, therefore, to develop a reaction equal to the resistance of the boat, the revolutions of the wheel and its slip must be increased to such an extent as to bring the paddles into earlier effective action, and at the same time to diminish the resistance due to back water.

With an immersion such that, with a reasonable amount of slip, the paddles would act effectively at the instant of entering the water, this wheel would doubtless give good results. During the three western trips, this condition was of course most nearly satisfied; and it is to this fact, in part at least, that the average speed in that direction,

against the current, exceeded by over a third of a mile an hour the average speed east.

VII. The "Excelsior."

This was an iron steamer, built at Green Point, N. Y., of full size,. and was represented by W. H. Mallory, Esq., of Bridgeport, Conn. Her launching weight was said to have been less than 30 tons.

The peculiarity of the "Excelsior" consisted in her propelling instrument, which was the Fowler wheel. This wheel, like those of the "Fountain City," is a paddle-wheel, revolving about a vertical axis. It has four blades, each two feet long by one foot wide, giving an aggregate surface of 8 square feet. Its axis was supported at the bottom by a plate or shoe extending aft from the keel and supported at its other extremity by an iron rod suspended from the hull above. The pitch of the blades of this wheel is adjustable by means of an eccentric upon the shaft, from the strap of which rods lead to and connect with arms upon the upper extremities of their axes. adjustment is effected by the steersman, who is thus enabled to direct the action of the wheel in such a manner as to cause it to drive the boat ahead, back it or turn it around within its own length without stopping or reversing the engine. This wheel, therefore, serves the double purpose of propeller and rudder, with the additional advantage that all the functions of these two instruments are performed simultaneously, while the direction of the motion of the wheel itself remains unchanged.

The

The engine of the "Excelsior" was a single cylinder, twelve inches in diameter by twenty inches stroke of piston, was provided with an independent adjustable cut-off valve upon the back of the main valve, and was non-condensing. The engine was connected directly with a crank upon the upper extremity of the wheel-shaft.

The boiler was horizontal, return-tubular, five feet in diameter and ten feet long; it had one flue twelve inches in diameter, two flues eight inches in diameter, and forty-four three-inch return tubes six feet in length. The grate surface was sixteen square feet, and the heating surface about 280 square feet. The exhaust could be turned into the smoke-stack, or outside, as desired. It was originally intended that the end of the boat containing the machinery should be the bow, but upon trial it was found not to work satisfactorily in that direction. In the other direction, however, she was found to perform to the entire satisfaction of her owners, except that the stern, which was built very full, did not serve the purpose of a bow quite as well as could have been desired.

This steamer entered the canal on the 4th of September last with a cargo of 100 tons of coal; but, in passing through the sixteen locks at Cohoes, a hole was stove in each bow, which, but for a water-tight bulk-head, would have caused her to sink. She, however, proceeded as far as Crescent, where she went upon the dock for repairs. I joined the steamer, at this point, on the 5th. It had already been decided, on account of the obvious frailty of the boat, and her evident inability to withstand the shocks which she would encounter in the canal, to return to New York and transfer the machinery to a wooden hull.

Major Mallory, however, for the purpose of exhibiting the capacity of his machinery, consented to make a run as far as lock 19, distant six miles from Crescent. Accordingly, on the morning of the 6th, the "Excelsior" left the dry-dock at 8 o'clock and ten minutes, and proceeded west. At 8.38 a line was caught in the wheel, which caused a detention of an hour and thirty-five minutes; at 10.50 proceeded and reached lock 19 at 12 o'clock noon. Running time, one hour and 46 minutes; average speed, against the current, 3.41 miles per hour. At 1.15 P. M. started on the return trip, and at 2.03 P. M., in endeavoring to pass a loaded boat at a point where the canal was obstructed by other boats, ran upon rocks upon the berme side and stove a hole in the port bilge. Upon backing off, a serious list to port indicated that the steamer was sinking. She was immediately backed into wide water and grounded on the berme side of the canal, where she soon filled with water. While running west the speed was at times as high as 3.8 miles per hour; running east with the current, four miles was exceeded. The coal expended during the six hours was 546 pounds; distance steamed, nine miles; average coal consumption per boat mile, 60.7 pounds. The engine was idle, however, over a third of the time.

The steam pressure ranged from 80 to 95 pounds, and the revolutions firm 80 to 100 per minute. Average steam, 89 pounds; average revolutions, 94 per minute.

The steam having been throttled during the entire run, and the effect of the throttling being very uncertain, it is impossible to determine what power was expended. Judging from the coal consumption, I think it did not exceed 35 to 40 horses.

As to the efficiency of the wheel, as compared with other propelling instruments, the test was not sufficiently prolonged to warrant an expression of opinion.