104 Prof. Magnus's Hydraulic Researches. 



dimension AB of the orifice, and fig. 15 6 that when looked at 

 at right angles to the narrow side BC of the aperture*. 



45. The water contracts very strongly after it has left the 

 orifice. Hence result the roundish edges Ae and B/, which are 

 very sharply defined towards the rest of the sui'face. These 

 produce, when they encounter centrally, the first surface fff, 

 which is at right angles to ABef. This surface fff assumes at 

 its lower half strong edges again, and by the encounter of these 

 the foUomng surface ffh is formed, which is again at right angles 

 to the preceding fff. Thus the process is repeated, and many 

 such similar surfaces are formed successivelj'^, just as in § 14, in 

 the case of the central encounter of two separate jets, which 

 formed an angle with each other. 



46. The dimensions of these surfaces alter with the pressure 

 under which the water issues. The greater the pressure, the 

 longer the sui-faces, i. e. the greater the distances fff, ffh, &c. 

 Their breadth ik, i^ki is also changed, but not in the same pro- 

 portion as the length. Hence it is, that, under greater pressure, 

 the surfaces appear more extended, i. e, their breadth is less in 

 proportion to their length. The distance from the efflux orifice 

 to the first contraction of the jet at ef changes also with the 

 pressure, and is greater when the pressure increases. Fig. 15 a 

 and b represent the surfaces under a pressure of 0'^"15. 



47. If, while the efflux orifice remains unchanged, the afflux 

 of water from two opposite sides be made unequal, by putting, 

 for instance, a piece of tin plate in the vessel near the long side 

 CD of the aperture upon the plate in which this is made, the jet 

 deviates from the vertical. It is bent then towards the side CD 

 near which is the tin plate. This bending or deviation from the 

 vertical is the stronger the thicker the plate is. With the ex- 

 ception of this bending, the form of the jet is just that described 

 in § 45, provided that the plate hinders the afflux of water equably 

 in the whole length of CD. 



If instead of bringing the hindrance on a broader, it be brought 

 on a narrower side of the aperture, for instance on the side AD, 

 the jet will deviate towards this side. Altogether the deviation 

 is towards that side from which the afflux takes place with less 

 rapidity. If the hindrance does not extend aU the length of the 

 side in question, it is obvious that the deviation which the stream 

 experiences when the afflux is hindered upon one of the narrower 

 sides, is far less than when the hindrance is on one of the longer 

 sides. This deviation not being considered, the form of the jet 

 remains in both cases just as if no such hindrance to the afflux 

 had been there. 



48. If hindrances to the afflux be brought on both the narrow 

 * In order to makethis more intelligible the cross sections a, /3,&c. are added. 



