HYDRODYNAMICS. 



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In the year 17+7, Professor Segner of Gottingen 

 published, in his Exercitationts Hydrauliae, an account 

 of a machine which differs only in form from Dr Bar- 

 ker's mill. It consisted of a number of tubes arranged 

 as it were in the circumference of a truncated cone ; 

 the water was introduced into the upper ends of these 

 tubes, and flowing out at the lower ends, produced, in 

 virtue of its reaction, a motion round the axis of the cone. 



Another form of this machine has been suggested by 

 Albert Euler. He proposes to introduce the water 

 from the mill course into an annular cavity in a fixed 

 vessel of the shape nearly of a cylinder The bot- 

 tom of this vessel has several inclined apertures for 

 the purpose of making the water flow out with a pro- 

 per obliquity into the inferior and moveablc \t . i 

 This inferior vessel, which has the form of an inverted 

 frustum of a cone, moves about an axis passing up 

 through the centre of the fixed vessel, and has a variety 

 of tubes arranged round its cirumference. These tubes 

 do not reach to the very top of the vessel, and are bent 

 into right angles at their lower ends. The water from 

 the upper and fixed vessel being delivered into the 

 tubes of the lower vessel, descends in the tubes, and is- 

 suing from their horizontal extremities, gives motion to 

 the conical drum by its reaction. 



The excellence of this method of employing the re- 

 action of water, was first slightly pointed out by Dr 

 Desaguliers, and no further notice si i ins to have been 

 taken of the invention till the appearance of Segner'* ma- 

 chine in 1 747. The attention of Leonhard Euler, John 

 Bernoulli, and Albert Euler, was then directed to the 

 subject, and it would appear, from the results of their 

 investigation*, that thu is the moat powerful of all hy- 

 draulic machines, and is therefore the best mod* of 

 emstleying water as a moving power. Leonhard Euler 

 published his theory of this machine in the Memr-ir* of 

 tke Berlin Academy, vol. vi. p. 3 1 1 ; and the application 

 f the machine to all kinds of work, was explained in 

 a subsequent paper in the seventh volume of the same 

 work, for 1752, p. 271. John Bernoulli'* investiga- 

 tion* will be found at the end of his Hydraulic*. 



Albert Euler concluded, that when the machine had 

 the form given to it by Segner, the effect was equal to 

 the power, and that the effect b a i"iri' when the 

 velocity i* infinite. Mr Waring, in the paper which 

 we have already quoted, makes the effect of the ma- 

 chine equal only to that of a good undershot wheel 

 driven with the same quantity of water falling through 

 the same height. The Abbe Bossut ha* likewise in- 

 vestigated the theory of this machine, and has loud 

 that an overshot wheel, and a wheel of the form given 

 to it by Albert Euler, will produce eaual effects with the 

 same quantity of water, if the depth of the orifice be- 

 low the mill-coune in the latter machine is equal to 

 the vertical height of the loaded arch in the overshot 

 wheel ; and be, upon the whole, raremmends the over- 

 shot wheel as preferable in practice. The preceding 

 result, however, proves the inferiority of the overshot 

 wheel, as the height of the loaded arch must be always 

 much leas than that of the fall. A new and ingenious 

 theory of this machine ha* lately been given by Mr 

 Ewart in the M**cke*trr Memo*,. 



For farther information on thia subject, see Desagu- 

 lier-* Experimental PUbtupmy, vol. ii. p. 453 ; Segner's 

 EjurcilaboHrt HydratLca, Gotting. 1747 ; L. Euler, 

 Mem. Acmd Serf 1751, voL vi. p. 31 1 ; Id. 1752, vol. 

 vii. p. 271; Waring, Ann-nan Transactions, vol. iii. 

 p. 185; M. Mathon de la tour in Hosier's Journal, 



VOL. XI. PA3T II. 



Jan. and Aug. 1775; Krafft, Nov. Comment. Petropol. Sluicfe 

 1792, vol. x. p. 137; Robison's System of Mechanical Governor. 

 Phi/otophy, Bossut's //yr/rcx/ynamu/nr, torn. i. chap, xviii; ^~~Y~*~' 

 Ferguson's Leilurtt, vol. ii. p. 97, and Appendix, p. 

 205; Gregory's Mechanic*, vol. ii. p. 106. 



SICT. V. On Machines Jbr Raising Water, and various 

 Hydraulic purposes. 



1. Description of a Sluice Governor for regulating the 

 Introduction of Water upon Water Wheels of all kinds. 



As there is a particular velocity at which water wheels Sluice g*. 

 produce a maximum effect, and as the work to be per- VCTOO*. 

 formed is often injured by an irregularity in the velocity 

 of tin- machinery, it is of great importance to regulate 

 the admission of the water so as to prevent any increase 

 of velocity when there is too much water in the mill- 

 course. In corn mills, the meal becomes heated and 

 injured by too great a velocity, and in cotton mills, the 

 threads are broken from the same cause. 



The machine for this purpose, which is minutely re- PLATE 

 presented in Plate CCCXX1. Figures 5, 6, 7, and 8, CCCXXI. 

 was actually constructed by the late Mr Burns for Cart- ** 3> 6> 

 side cotton mill, who considered it of such advantage as ' ' 

 to produce a saving of more than 100 per annum. 

 The motion of the water wheel is communicated by a 

 belt or rope going round the pulley I to the axis EF, 

 which carries the balls G, H, Fig. 5. This motion is 

 conveyed to the upright shaft T by the wheels and pi- 

 nions Q, R, S, T, and the wheel X at the bottom of tin- 

 shaft drives the wheels O, I', Fig. 6 and 7, in opposite 

 direction*. When the velocity of the wheel is such as 

 is required, the wheels O, P move loosely about the axis, 

 and carry the motion no farther. But when the velo- 

 city of the wheel is too great, the balls G, H, separated 

 by the increase of centrifugal force, raise the box a upon 

 the shaft EF. An iron cross b c, see Fig. 8, is fitted into 

 the box 'a. This cross works in the four prong* of the 

 fork e b c, Fig. 6, at the end of the lever d qfe, which 

 move* horizontally round f a* its centre of motion. 

 When the box a it stationary, which is when the wheel 

 has its proper velocity, the iron cross works within 

 two of the prongs so as not to affect the lever dfc, but 

 to allow the clutch i/ q, fixed at the end of the lever, to 

 be di*engaged from the wheels. When the cross b c rises, 

 it strike* in turning round the prong 3, see Fig. 8. which 

 drive* aside the lever eftl, and throws the clutch q into 

 the arm* of the wheel P, Figs. 6, 7. This causes it to drive 

 round the shaft DC in one direction. When the iron cross 

 b c, on the contrary, i* depressed by any diminution in 

 the velocity of the wheel, it strikes, in turning round, 

 the prong 4, which pushes aside the lever rfd, and 

 throws the clutch q' into the wheel O. This causes 

 the wheel O to drive the haft in an opposite direction 

 to that in which it was driven by P. Now the shaft 

 DC, which is thus put in motion, drives, by means 

 of the pinion C and wheel B, the inclined shaft BW, 

 which, by an endless screw X working in the tooth- 

 ed quadrant 7., elevates or depresses the sluice KL, 

 and admits a greater or a less quantity of water, 

 according as the motion is given to the shaft by the 

 wheel P or O. This change in the aperture i* pro- 

 duced very gradually, as the train of wheel work is 

 made so as to reduce the motion at the sluice. The 

 centre in which the sluice turns should be | of its 

 height from the bottom, in order that the pressure of 

 the water on the pan above the centre may balance the 

 pressure on the part below the centre. 

 4 



