ISIS"] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL, 



235 



old wheels, was a serious counterpoise to tlie power of tlie wheel, 

 as the ascending buckets carried with them portions of the water 

 to a considerable height, on the opposite side of the vertical cen- 

 tre. In the improved construction, this defect is obviated, as the 

 opening which allows the air to escape, during the filling of the 

 buclvets, re-admits it with the same facility during the discharge : 

 there cannot, consequently, be any formation of a partial vacuum, 

 and the wheel not only works easily, but to a much greater depth 

 in the back-water. It has also been found necessary, in order to 

 facilitate the escape of the water, to terminate the breast at a dis- 

 tance of about 10 inches from the vertical centre, and always to 

 have a depth of from 18 inches to '2 feet of water under the bottom 

 of the wheel. 



These are considerations of some value, as the abrupt termina- 

 tion of the breast admits of a much quicker discharge of the water 

 from the buckets, and the increased depth of the tail-race gives 

 room for its escape, after it has passed from the wheel. In fact, 

 the benefits arising from this form of breast, and tail-race, are so 

 great, that they should be strictly enforced, where it is desirable to 

 have the full and eft'ective use of the fall. In the erection of water- 

 wheels, these principles should never be lost sight of; and instead 

 of a shallow tail-race, with the water running from the wheel at a 

 rate of from 6 to 8 feet per second, as is frequently the case with 

 the old wheels, the current should be scarcely perceptible, and the 

 water should always flow as steadily and as smooth as in a deep 

 canal. 



It would, perhaps, be difficult to describe with accuracy the pro- 

 perties and proportions of these improvements, without a long 

 series of costly experiments upon a large scale; and in order to 

 make the comparison perfect, the new and old forms of water- 

 wheels should be placed in juxta-position, each having a propor- 

 tionate load, and %vorking, as nearly as possible, under the same 

 conditions, both as to the fall and the supply of water. Under 

 these circumstances, the great difference which exists between the 

 one kind and the other would become apparent, not only as re- 

 spects superior economy, but also the perfect ease with which the 

 ventilated wheel overcomes the resistance of the load, and the 

 obstructions of back-water to which wheels are subject in times of 

 floods. 



On some future occasion an opportunity may present itself for 

 returning to this subject, when the superiority of water-wheels with 

 ventilated buckets may be confirmed by more detailed experiments, 

 and when the relative forms of wheels and buckets may be re- 

 spectively established. For the present, it will suffice to observe, 

 that the wheel already described will be found in practice exceed- 

 ingly effective, and probably the best adapted, with certain modifi- 

 cations, for falls not exceeding 10 feet in height. 



Breast-Wheels, with Close Soles, and Ventilated Buckets. 



The preceding statements have been principally confined to the 

 form of bucket, and description of water-wheel, adapted for low 

 falls. It will now be necessary to describe the best form of breast- 

 wheels for high falls, or those best calculated for attaining a maxi- 

 mum effect on falls varying from one-half to three-fourths of the 

 diameter of the wheel. This is a description of water-wheel in 

 common use, and is generally adopted for falls which do not exceed 

 ' 18 feet in height, and, in most cases, is preferable to the overshot 

 wheel. It possesses many advantages over the undershot wlieel, 

 and its near approximation to the duty, or labouring force, of 

 wheels of the former description, renders it applicable in many 

 situations, especially where the fall does not exceed 18 or 20 feet, 

 and where the wheel is exposed to the obstructions of back-water. 

 In the latter case, wheels of larger diameter are best adapted; and 

 provided sufficient capacity is left in the buckets, such wlieels may 

 be forced through the back-water without diminution of speed. 

 Every wheel of this kind should have capacity in the buckets to 

 receive a sufficient quantity of water to force the wheel, at full 

 speed, through a depth of five or six feet of back-water; and if 

 these provisions are made, a steady uniform speed, under every 

 circumstance of freshes and flood-waters, may be attained. 



A water-wheel of this kind, of 100-horse power, was constructed 

 for T. Ainsworth, Esq., of Cleator, near Whitehaven, about four 

 years back, for driving a flax-mill; it is 20 feet in diameter, 22 feet 

 wide inside the bucket, and 22 inches deep on the shroud. It has 

 a close-riveted sole, composed of No. 10 wire-gage iron plate, and 

 the buckets are ventilated from one to the other, as shown in the 

 engraving, fig. 5. The fall is 17 feet, and the water is discharged 

 upon the wheel by a circular shuttle, which is raised and lowered 

 by a governor, as circumstances require. By this arrangement 

 the whole height of the fall is rendered available, and the water, 

 in dry seasons, may be drawn down from three to four feet, in 



order to afford time for the dam to fill, during the periods of rest, 

 either during the night, or at meal-times. 

 In this wheel, the power is taken from 

 each side by two pinions working into in- 

 ternal segments, and these again give mo- 

 tion to shafts and wlieels, whicli communi- 

 cate with the machinery of two different 

 mills, at some distance from each other. 

 The position of the pinion, or the point 

 where it 'gears' into the segments, is of 

 some importance in every water-wheel, but 

 more particularly in those constructed on 

 the suspension principle, which, upon in- 

 spection, will be found but indifferently 

 prepared to resist a torsive strain, when 

 the power is taken from the opposite side 

 of the loaded <trc of the wheel. Water- 

 wheels of this construction, with malleable 

 iron rods only 2 inches in diameter for 

 their support, could not resist the strain, 

 but would twist round upon the axle as a 

 fixed centre of motion. It therefore be- 

 comes necessary, on every occasion, to 

 take the power from the loaded side of 

 the wheel, and as near the circumference 

 as possible, in order to throw the weight 

 of the water upon the resistance of the 

 pinion, and that such resistance shall be F'e- s. 



at the point of the greatest velocity. 



In the old water-wheels, where the power was generally taken 

 from the axle, the whole of the force first passed through the arms 

 to the axle, and afterwards by a pit-wheel, or some other multiplier 

 of speed, to the machinery in the mill. Now, in the improved 

 wheels, this is not the case, as the arms, braces, and axle have only to 

 sustain the weight of the wheel, and to keep it in shape; and by'the 

 power being taken from the circumference, considerable complexity 

 in the transmission of the power is avoided: a great saving is also 

 effected when the speed re(|uired is greater than that of the wlieel. 

 It has already been shown that this description of wheel has a close 

 sole; and on reference to the figure it will be found that the tail- 

 ends of the buckets «, a, a, are turned up at a distance of 2 

 inches from the back of the sole-plate, and, running parallel 

 with that part, terminate within about 2 inches from the bend of 

 the upper bucket. The object of this construction is obvious, as 

 the water in passing through the openings between the buckets 

 drives the air before it, in the direction of the arrows at «, a, a, 

 into the bucket above, and so on in succession, till each bucket is 

 filled as it passes the aperture of the cistern from which the water 

 flows upon the wheel. Iriespective of the advantages of clearing 

 the buckets of air, additional benefit is obtained by the facility 

 with which the water is discharged, and the air again admitted, at 

 the bottom of the fall, during the period of the emptying of the 

 bucket into the tail-race. This is strikingly illustrated wliere tlie 

 wheels labour in back-water, as the ventilated buckets rise freely 

 above the surface, and the communication being open from one to 

 the other, tlie action is rendered perfectly free, at almost any 

 depth to which the wheel may be immersed. 



In breast-wheels constructed for falls of 25 feet or upwards, the 

 stone-breast is not required, as the buckets are foi'med with narrow 

 openings, and the lip being extended nearer to the back of the fol- 

 lowing bucket, the water is retained much longer upon the wheel. 

 Under these circumstances, a stone-breast is of little or no value, 

 when attached to a wheel with close buckets, on a high fall. 



The construction of the breast-wheels, as above described, is 

 almost exactly similar to that for tlie lower falls; malleable iron 

 arms and braces being common to both, as also the axle, shroud, 

 and segments. These, when duly proportioned and properly fitted 

 to each other, form one of the strongest, and probably the most 

 permanent structures, that can be attained in works of this de- 

 scription. 



Common Breast-Wheel fuot ventilated), as constructed by Slessrs. 

 Fairbairn and Liltie, between the years 1825 and 182T. 



These wheels were executed upon the plan of the overshot or 

 breast-wheel, taking the water at an elevation nearly equal to that 

 of its height. Four wheels of this description were constructed 

 for Messrs. James Finlay and Co., for a fall of 32 feet, at Deanston, 

 in Perthshire, and two others, for the same firm, at tlie C'atrine 

 AV^orks, in Ayrshire, on a fall of 48 feet. Taking into considera- 

 tion the height of the fall, the Cati-ine water-wheels, both as re- 

 gards their power and the solidity of their construction, are, even 



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