The length of stroke in the pumps was 6 feet; and the effective motion in the pumps to raise water, was at the rate of 30 feet per minute. The weight of the columns of water in all the 6 pumps, amounted to 66,415 lbs. weight, which being raised 30 feet per minute 1,992,450 lbs. per minute raised 1 foot; that is, the power realized or exerted in actually raising the water; or being divided by 33,000, gives 60 36 horse power realized. Wherefore an expenditure of water power equal to 2,872,320 lbs. per minute, descending 1 foot (or 87.0 H. P.) produced a useful effect, realized in water raised by the pumps, equal to 1,992,450 lbs. per minute raised 1 foot (or 60·36 H. p.). The useful effect or work done, being at the rate of 69-4 per cent. of the power expended, the remaining 30.6 per cent. being lost, partly by friction of the pump-work, and resistance to the motion of the water through the pumps, and partly by imperfect application of the water to the wheel. II. Taylor's North Wheel, 50 feet diameter, 63 feet broad, was supplied with 5,199 gallons of water per minute = 78:75 H. P. expended. It made 5 revolutions per minute, and worked 6 pumps with a stroke of 6 feet; weight of the columns of water in those pumps, 44,689 lbs., which was raised 30 feet per minute = 40·63 H. ỵ. realized; being 51.6 per cent. of the power expended. III. Taylor's South Wheel, 40 feet diameter, 4 feet broad; supplied with 4167.4 gallons = 50.5 H. P. expended. It worked 2 pumps, 6 feet stroke, 5 strokes per minute; weight of columns 30,270 lbs. = 27.53 H. P. realized; being 54.5 per cent. IV. Brenton's Wheel, 32 feet diam., 73 feet broad; supplied with 8897.4 gallons = 86.3 H. P. expended. It worked 5 pumps, 6 feet stroke, 4 strokes per minute; weight of column 30,092 lbs. 24.63 H. P. realized; being only 28.5 per cent. of the power expended, which is to be accounted for, by the additional friction of a great length of horizontal rods by which this wheel works its pumps. OVERSHOT WATER WHEELS AT WHEAL BETSY MINES, IN JULY, 1841. I. Job's Wheel, 42 feet diam., supplied with 2890 gallons of water per minute 36'78 H. P. expended. It made 4 revolutions per minute. Weight of the columns of water in the pumps 28,314 lbs. 6 feet stroke = 20'6 H. P. realized, being 56 per cent. II. Williams's Wheel, 40 feet diam.; 3027 gallons per minute = 36·68 H. P. expended. It made 4 revolutions. Weight of columns 26,454 lbs. ; 7 feet stroke 26'45 H. P. realized; being 72.1 per cent. 23.17 H. p. III. Buller's Wheel, 40 feet diam., 1912 gallons expended. It made 3 revolutions. Weight of columns 22.901 lbs. 7 feet stroke 15.61 H. P. realized; being 67.4 per cent. IV. Carpenter's Wheel, 44 feet diam., 1985 gallons = 26'46 H. P. expended. It made 4 revolutions. Weight of columns 18,662 lbs., 6 feet stroke = 15.26 H. P. realized; being 57.6 per cent. Conclusion. If Brenton's Wheel at Wheal Friendship is rejected, as an extreme case, the average performance of the other three wheels, at Wheal Friendship, will be 58.5 per cent.; and of the four wheels, at Wheal Betsy, 63.3 per cent. Or the average performance of all the seven wheels, will be 61.2 per cent. Wheal Old Sump 69.4 Friendship.Taylor's South. 54-5) Taylor's North. 51.658.5 per cent. Wheal Job's .. 56.0 Carpenter's... 57.6) Mr. Jordan described the Turbine to consist of three principal parts. 1st. A cylinder with a base, upon which are fixed the guide curves, directing the water at a certain angle upon the buckets of the moving ring. 2nd. A sluice, regulating the flow of water from the bottom of the cylinder upon the buckets; and 3rd. The external or revolving ring, with its buckets and its upright shaft, whence the motion is communicated to the machinery to be driven. 66 The buckets are confined between two annular plates, the lower one being attached to the vertical shaft, in the bottom of which, is fitted a hardened steel thimble, into which a pivot of glass-hard-steel" works; this inversion of the ordinary ar rangement of the pivot, is to prevent any particles of sand or other substances from getting upon the point, and producing friction. Oil is introduced to this pivot by a tube connected with a small pump, worked by the machinery at the requisite speed, to keep it lubricated. The form of the buckets is a mathematical curve, and on the perfection with which this is traced, will depend the efficiency of the Turbine. These parts are enclosed within a cylinder, so arranged that it shall serve as the reservoir, whence the water is admitted upon the moving parts by the sluice, which must be well fitted to prevent a loss of water, and is uniformly raised or lowered by gearing, placed on the top of the cylinder. When the height of the fall is considerable, the cylinder is closely covered, and the moving shaft passes through a stuffing box in the centre; but with low falls, the cylinder is open at the top. A great advantage in the machine is, that the castings and ironwork composing it, are (with the exception of the buckets) very simple, they require little adjustment, and only a few parts are turned or bored, so that the construction ought to be economical. Mr. Rennie had endeavoured to introduce the Turbine into notice some years ago, and the nature of the curves had been examined in an article in Herapath's Magazine. Professor Gordon's statement corresponded very nearly with what he had heard from MM. Fourneyron, Arago, and Morin, and subsequently seen of these machines when in France. He had visited a Turbine, erected by a Mr. Isterwood, at a flour-mill at St. Maur, near Paris; the machine drove ten pairs of millstones, 3 feet 4 inches in diameter, at the rate of two hundred revolutions per minute, VOL. XXI. S equalling forty horses' power: subsequently, three additional Turbines were erected, for the purpose of driving ten pairs of stones each, or in all, forty pairs of stones, by four machines.— Each Turbine had a diameter of 5 feet 2 inches, and a depth of bucket of 8 inches, with a fall of water of about 6 feet: when entirely submerged to the depth of 4 feet, the Turbine continued to make (as in low water) 50 revolutions per minute. Subsequently, in September 1840, he visited the flour-mills of M. D'Arblay, at Corbeil. These mills are four in number, arranged in a quadrangular form; each mill contains ten pairs of mill-stones, which were originally driven by four well-proportioned cast-iron wheels, of about 18 feet diameter; two out of the four wheels were still at work, but the other two had been replaced by two Turbines, similar in dimensions to those at St. Maur. One of them was working ten pairs of stones. The motion was communicated to a horizontal shaft, by means of bevil wheels, one fixed on the upper extremity of the upright spindle of the Turbine, the other, of smaller diameter, fixed on the end of the horizontal shaft, on which also were fixed the riggers, for driving, by means of straps, smaller riggers, fixed on the mill-stone spindles. The work was very regularly done, and the proprietors expressed great satisfaction. The second Turbine was then erecting, and the third and fourth water-wheels were to be replaced by similar machines. No fault was attributed to the original wheels, but their effect was not equal to that of the Turbines. The maker (Mr. Isterwood) stated that he had made these machines entirely under the direction of M. Fourneyron, who alone knew how to trace the directing and emissive curves, and that, unless they were properly described, the effect would be greatly reduced. He at the same time stated, as his opinion, that there was no economy in the construction of the Turbine over the common water-wheel, as the former is more complicated and costly. M. Fourneyron seemed to doubt whether any other machinist than himself could construct a Turbine properly; the principal difficulty being in tracing the curves, which had been the study of his life; he quoted several instances of failure when strangers had attempted their construction. M. Arago and M. Poncelet were of the same opinion: the former stated, that the effect of the curves was contrary to theory. M. Morin expressed his confidence in the accuracy of the experiment made with the frene or friction brake of Prony, applied to the axes of the Turbines. Mr. Rennie had seen a cast-iron water-wheel, with close buckets, very nicely balanced, 24 feet diameter and 5 feet 6 inches. wide, made under the direction of his father, realize 80 per cent. of effective power, and Professor Gordon, in the paper, spoke of 82 per cent. for an overshot water-wheel. He did not, however, by these observations, mean to disparage the Turbine, with which the mechanical world generally was not sufficiently acquainted. Mr. Taylor thought, that Mr. Rennie had overlooked the two prominent advantages of the Turbine, in comparing it with other methods of employing water power. 1st. That of its being equally adapted for very low or for very high falls in falls under 10 feet, the breast-wheel afforded but an imperfect mode of using the power, as the actual efficiency fell far below what ought to be obtained by a more perfect machine; and in falls above 50 or 60 feet, if overshot wheels were used, a number of them must be constructed, with the disadvantage of increased expense, and probable inconvenience in their application. Instances had been adduced of Turbines working with a fall as low as 2 feet, and as high as 345 feet; the efficiency of the former, being stated at 64 per cent. and of the latter, from 80 to 85 per cent. 2nd. That they are not affected by back or tail water, like almost all other hydraulic machines; it having been shown by direct experiment, that, when working at considerable depths under water, the relative proportion of useful effect produced, to the total mechanical effect expended, is not thereby notably diminished. This, in his opinion, was one of the most important advantages of the Turbine. For high falls, the water-pressure engine and Barker's mill, as improved by Whitelaw and Stirratt, rivalled the Turbine; and |