HYDROSTATICS. 



25 



below the surface ought to draw it 

 down as much as the ring; immediately 

 above draws it up. Others hold, that 

 the first ring of glass which meets the 

 water, that is, the bottom of the tube, 

 attracts it, there being no ring below to 

 draw it down. But this seems not very 

 well to explain how this ring pushes 

 the water up past it ; for it ought na- 

 turally to draw it back as much as the 

 second ring draws it up ; and still less how 

 the water remains suspended without 

 running out at the top, when you break 

 off the tube below the point to which it 

 rises. However, the fact of the water 

 rising higher the smaller the tube is, 

 cannot be doubted, and there are some 

 other facts equally well ascertained. 



If a tube have, in different jig. 25. 

 parts, two bores, as A D 

 the larger, and E F the 

 smaller, the water will rise 

 from A B into E F, and 

 stand at the same height E, 

 at which it would have stood , 

 if the small tube E F were 

 continued down to the sur- 

 face of the water A B ; 

 and this will take place 

 whatever be the bore or 

 shape of A B D C, provided E F be a 

 capillary tube: so that the water will 

 stand in the larger tube, or in any vessel 

 ending in a capillary tube, as well as if 

 it were closed at the top ; but if the 

 tube or vessel be turned upside down, 

 the water will only stand as high as it 

 would have done hi the larger tube alone, 

 and consequently it will not rise into 

 that tube at all, "unless it be capillary. 



If a capillary tube, like the one above, 

 composed of two, or a tube tapering to 

 one end, be filled with liquid, and placed 

 horizontally, the liquid will run towards 

 the narrow part, and leave the wide 

 part towards the mouth empty. 



If a capillary tube be bent into the 

 form of a syphon, the water will ri>e 

 as high as it' it were straight, and so 

 may reach the middle of the bend, but 

 it will not run over through the other 

 leg. If the syphon, however, is filled 

 in" both legs, "and one is made so much 

 longer as to counterbalance the attrac- 

 tion which keeps it in the other, it will 

 flow over, and will thus bring the water 

 from one place to another. 



If a plate of glass be placed with its 

 upright edge against another plate, and 

 kept in a slanting position towards it, at 



an inclination to it of about l-3Gth part 

 perpendicular, (that is, at an angle of 

 about 24 deg.), and the lower edges of 

 both plates be placed in any watery 

 liquid, the liquid will rise between the 

 plates, and it will rise higher the nearer 

 it is to the upright edge ; that is, the 

 smaller the space is between the two 

 plates ; so that the liquid will form itself 

 into a curve line. Thus, if the plates 

 ABDCandAEFC (fig. 26.) meet in 



fig. 26. 



the edge AC, and are held very near each 

 other, but not touching, except in A C, 

 the liquid in which they are placed will 

 rise between them, and stand in the 

 form of D I G L ; the height of the 

 liquid at any point G, that is G H, 

 being greater in proportion as its dis- 

 tance from A is less. So that, if C K 

 is twice as long as C H, I K, will be 

 half as long as G H. This curve is 

 well known to mathematicians. It is 

 the same line which is made by cutting 

 a cone through its sides and base, 

 in a direction perpendicular to its base. 

 When water is the liquid, it rises to 

 the height of an inch at the point where 

 the two plates are 1-1 00th of an inch 

 asunder, and so in proportion, the height 

 being half an inch where the distance 

 is l-50th, or two inches where the dis- 

 tance is 1 -200th of an inch. And if the 

 plates are held parallel to one another, 

 and very near, the upper edge of the 

 liquid will be a straight line. This rise 

 is plainly owing to the same attraction 

 which acts irf capillary tubes ; for 

 the two plates may be considered as 

 an assemblage of an infinite number of 

 capillary tubes of bores always dimi- 

 nishing till at A B the bore is "nothing. 

 So if a number of capillary tubes, each 

 one smaller than the next, be placed up- 

 right in a row and resting upon a liquid, 

 it will rise in them to different heights; 



