266 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Air GUST, 



are nientioiieil ; tliea are noticed the experiments of MM. Tardy and Piobert, 

 and the allusion by Borda to horizontal wheels ; then a general description 

 is given of the numerous experiments made up to the year 1825, when M. 

 Burdin constnicted wheels in which the water was received at the circum- 

 ference of a vertical cylinder, descended in conduits, placed in a helical form 

 round the surface of "the cylinder, and made its escape at the bottom : the 

 etficiencv of these wheels was stated to be 75 per cent., but no exact 

 experiments were ever institvited. 



Tlie defects in all the previous machines led to the invention of the Turbine 

 as it is now designed by M. Fourneyron : its construction may be compared 

 to one of Poncelet's wheels with curved buckets, laid on its side, the water 

 being made to enter from the interior of the wheel, flowing along the buckets, 

 and escaping at the outer circumference ; centrifugal force here becomes a 

 substitute for the force of gravity. 



The mechanical construction of the Turbine is then given, and its action 

 is thus described. The water when admitted to the reservoir rises to a 

 certain level, exercising a hydrostatic pressure proportional to the heiglit of 

 the column, and on the sluice being raised it escapes with a corresponding 

 velocity in the direction of the tangent to the last element of the guide 

 curves," which is a tangent to the first element of the curved buckets; the 

 water pressing without shock upon the buckets at every point of the inner 

 periphery, causes the wheel to revolve, then passes along the buckets, and 

 escapes at every point of the outer periphery ; by which arrangement the 

 size of the machine even for a large expenditure of water is kept within narrow 

 limits. 



The advantages of the Turbines are stated to he — 



1st. That they are with like advantage applicable to every height of fall, 

 expending quantities of water proportional to the stjuare root of the fall, 

 their angular velocities being likewise proportional to these square roots. 

 2nd. That their net efficiency is from 70 to 75 per cent. 

 3rd. That they may work at velocities much above or below that corres- 

 ponding to the maximum of useful effect, the useful effect varying very 

 little from the maximum nevertheless, and — 



4th. They work at considerable depths under water, the relation of the 

 useful effect produced to the total mechanical effect expended not being 

 thereby notably diminished. 



These advantages are stated to have been realized in the extensive practice 

 of M. Fourneyron, of M. Brendel in Saxony, and of Herr Carliczeck in 

 Silesia, as well as other engineers. 



A comparison of the theory and practice of the construction is then 

 instituted, and the following conclusion is drawn : — That if one Turbine has 

 been constructed which works well under a known fall, expending a volume 

 of water exactly measured, this Turbine would serve as a type for all others. 

 Knowing the fall ane the volume of water to be expended, the Turbine 

 would be made similar to its type. Its Hnear dimensions would lie those of 

 the type, directly as the square roots of the volume of water, and inversely 

 as the fourth roots of the heights of fall. Its angular velocity would be to 

 that of the type, directly as the fourth roots of the cubes of the heights of 

 fall, and inversely as tlie square roots of the volumes of water. These 

 pracical rules were first made manifest by M. Combe of the Ecole des Mines. 

 A general review is then given of most of the Turbines erected by M. 

 Fourneyron at Pont sur I'Ognon, at Fraisans, at Niederbronne, and at Inval, 

 upon which last were tried the experiments which completely estabUshed the 

 reputation of the Turbine as an applicable machine. The details of these 

 experiments are given, whence the mean results appear to be, that the height 

 of fall being 6 ft. 6 in. — 



With au expenditure of 35 cubic ft. of water per second, the efficiency 



63 



79 



126 



144 



„ (forwhich it was constructed) = 



0-71 

 0-75 



0-87 

 0-81 

 0-80 



These experiments were tried by the application of Prony's Brake Dyna- 

 mometer, to the vertical shaft of the Turbine itself. 



M. .\rago's proposition for employing the power of one branch of the river 

 Seine upon Turbines, to replace the wheels at the Pont Kutre Dame, thus 

 giving about 2000 horse power for supplying Paris with water, is then men- 

 tioned, as also the results of experiments with very low falls; showing that 



With a fall of 3 ft. 9 in. the efficiency of the Turbine was = 0-71 

 2 ft. „ = 0-64 



10 in. „ = 0-38 



The Turbines of Miilbach and Moussay are mentioned, as are the failures 

 of several of these machines constructed by other engineers, and the paper 

 concludes with an account of a Turbine at St. Blazeux in the Black Forest, 

 ■where the height of the fall is 345 ft., the quantity of water 1 cubic foot per 

 second, and the reported efficiency from 80 to 85 per cent.* 



Remarks. — Mr. Taylor said that Professor Gordon's Paper on the Turbine 

 had been brought before the Institution with the advantages of illustration 

 afforded by the model made under the superintendence of Mr. Jordan for 

 the .Museum of Economic Geology; a most useful institution, for the present 

 advanced state of which the country is in a great degree indebted to the 



' The discussion upon Professor Gordon's, and Pmfessor Mcseley's Papers 

 extended over several evenings, but are all recorded logelher for the sake of 

 acility of reference. 



zeal and scientific knowledge of Mr. De la Bcche, who conducts tlie geo- 

 logical survey of the kingdom ordered Ijy the Board of Ordnance. 



The Institution was indebted to the courtesy of Mr. De la Beche for the 

 exhibition of the model, and Mr. Taylor had been anxious that the subject 

 should be brought forward at this time, as the only period at wliich such a 

 permission could have been granted ; for models once deposited in the 

 museum were not allowed to be removed. But it had been arrested in its 

 passage from the hands of its maker, and thus had been procured for the 

 inspection of members of the I.stitution. 



Mr. Taylor then proceeded to remark, that, although the improvements in 

 the application of steam had rendered water power of less value than for- 

 merly, yet there were many situations, particularly in the mining and high- 

 laud districts, where it was still employed beneficially. And as an instance 

 of the extent to which water power might be applied, he mentioned a case 

 in Devonshire, where in the adjoining mines of Wheal Betsey and Wheal 

 Friendship, near Tavistock, which have for many years been under his ma- 

 nagement, a fall of water of 526 ft. in height is employed in giving motion 

 to seventeen overshot wheels, eight of them performing the duties of pump- 

 ing water from a depth of nearly 200 fathoms. The diameter of the largest 

 of these wheels being 51 ft. with a width of breast of 10 ft. clear within the 

 rings, the smallest of the eight being 32 ft. diameter, and the others of 

 intermediate sizes. 



Four other wheels give motion to machines for drawing up the ores to the 

 surface, tlieir diameters varying from 40 to 26 ft.; and the five remaining 

 wheels are employed for mills for crushing and stamping tlie ores. In 

 addition to all this power, a steam-engine with a cylinder of 80 in. diameter, 

 and 10 ft. stroke, is provided as an auxiliary in periods of drought or frost. 



He then gave tbe distribution of this water power in the following tabular 

 form : — 



Overshot Water Wheels employed in pumping water atM'heal Friend- 

 ship Lead and Copper Mines, near Tavistock, in July, 1841. From data fur- 

 nished by Mr. Anthony Rouse, engineer at those mines. 



All the wheels operate on their pumps by means of a simple crank formed 

 on each end of the centre axis or gudgeon, on which the wheel is mounted. 

 Two long rods extend nearly in a horizontal direction, from the pins of those 

 cranks, to the upright arms of two bell-crank or elhow levers, which are 

 situated at the mouth of the pit, or shaft, and from the horizontal arms of 

 those elbow levers, two vertical pump-rods are suspended, in the pit. Those 

 rods and the pump-work are the same as commonly used for steam engines 

 in Cornwall, with plunger pumps, except that there are two pump-rods in 

 each pit, and they move up and down iu contrary directions, owing to the 

 two cranks on the ends of the axis of the water-wheel being bended in op- 

 posite directions ; by that arrangement the weight of the two rods counter, 

 balance one another; one half of the pumps are connected to one rod, and 

 the other half to the other rod, and the water is raised in the pumps by 

 turns. All tlie wheels have a considerable length of horizontal rods, to ex- 

 tend from their cranks to the elbow or bell-crank levers at the pit's mouth ; 

 and in some cases a very considerable length of such rods, occasioning much 

 friction. 



1. Old Sump Wheel, 51 feet in diameter, 10 feet broad. Thewater poured 

 into its buckets was at the rate of 5632 gallons per minute ; which, at 10 lb. 

 per gallon, would be 56,320 lb. weight, descending 51 feet = 2,872,320 lb. 

 per minute descending 1 foot; that is, the power of the water expended; or 

 being divided by 33,000 lb. (for a horse power according to .Mr. Watt) gives 

 87-0 horse power expended. 



The wheel when so supplied made 5 revolutions per minute, and worked 

 6 pumps, as follows : — 



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 feel per minute. 



The weight of the columns of water in all the 6 pumps, amounted to 

 66,415 lb. weiglit, whicii being raised 30 feet per minute= 1,992,450 lb. 

 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 

 reahzed. 



Wherefore an expenditure of water power equal to 2,872,3201b. per 

 minute descending 1 foot (or 87'0 h.p.) produced a useful effect realized in 

 water raised by the pumps, equal to 1,992,4501b. per minute raised 1 foot 

 (or 60'30 H.r.) ; the useful effect or work done being at the rate of 09-4 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 



