70. =Farther Illustrations.=--When you see stems of plants rising above the surface of stagnant water you will observe that the water is considerably raised about them. This is from the attraction between them and the water. For the same reason water is not as high in the middle of a tumbler as it is at the sides. If you immerse a piece of glass in water, the water will rise at its sides as represented in Fig. 16. If you immerse two together, as in Fig. 17, the water will rise higher between than outside of them, because the particles between are attracted by two surfaces, while those outside are attracted only by one. It is for the same reason that two men can raise a weight higher than one of them can alone. And if the pieces of glass be brought quite near together, as in Fig. 18, the water will be raised higher still, because there is less to be raised by the two surfaces. It is just as two men can raise a small weight higher than they can a large one. The same thing may be beautifully illustrated in this way: Let two pieces of glass, as represented in Fig. 19, be immersed in colored water, with two of their edges joined together at A B, the opposite edges at E D C being separated. The height to which the fluid rises will make a curved line, A F C, it being lowest at the edges which are separated, and highest at the edges which are joined together. [Illustration: Fig. 20.] [Illustration: Fig. 21.] 71. =Rise of Liquids in Tubes.=--For the same reason that water rises higher between plates of glass than outside, so it will rise higher in a tube than it will outside of it. The diagram in Fig. 20 will make this clear. I represent in this a transverse section of a tube, enlarged so that the demonstration may be plain. We will take a particle on the inside and the outside at equal distances from the glass. It is clear that the particle _a_ is not as near to as many particles of the glass as the particle _b_ is. The lines drawn show this. The longest lines extending from the particles _a_ and _b_ to the glass are equal in length; that is, _a e_ and _a f_ are equal to _b g_ and _b h_. It is clear, therefore, that all the glass between the lines at _c_ and _d_ is as near to the particle _b_ as the glass between the lines at e and _f_ is to the particle _a_. But this is not all. The particle _b_ is near enough to all the inside of the tube to be attracted by it, while very little attraction is exerted upon _a_ by any part of the glass beyond that which is included between _e_ and _f_. The same difference can be shown with regard to all the particles on the inside of the tube compared with those outside. The former are nearer to more particles of the glass than the latter, and therefore are more strongly attracted. Again, as the nearer the plates of glass are (§ 70) the higher the water rises between them, so the smaller the tube is the higher will the water rise in it. You can try the experiment as represented in Fig. 21. It is obvious that the