(1.) _When small tubes, open at both ends, are immersed perpendicularly in any liquid, the liquid rises in them, to a height which is inversely as the diameter of the bore._ Though tubes of glass are usually employed in experiments on this subject, yet tubes made of any other material exhibit the same property. Nor does the thickness of the solid part of the tube, or its quantity of matter, make the least difference, the effect depending solely on the attraction of the surface, and consequently extending only to a very small distance. (2.) _Different fluids are raised to unequal heights by the same tube._ Thus, according to experiment, a tube which will raise water 23 inches will raise alcohol only 9 inches. (3.) A tube 1/100 of an inch in diameter raises water 5.3 inches; and since the height is reciprocally as the diameter, _the product of the diameter into the height is a constant quantity_, namely, the .053th part of an inch square. (4.) _Fluids rise in a similar manner between plates of glass, metal, &c._, placed perpendicularly in the fluids, and near to one another. If the plates are parallel, the height to which a fluid will rise, is _inversely as the distance between the plates_; and the whole ascent is just _half that which takes place in a tube_ of the same diameter. If the plates be placed edge to edge, so as to form an angle, and they be immersed in water, with the line of their intersection vertical, the water will ascend between them in a _curve_ having its vertex at the angle of intersection. This curve is found to have the properties and form of the _hyperbola_. In the adjustment of the stems of barometers and the thermometer an allowance is made to compensate for the influence of capillary attraction. [Illustration: FIGS. 94-96.] Such are the leading facts ascertained respecting capillary attraction. Various explanations of them have been attempted but that of La Place is most generally received. According to this high authority, the action of the sides of the tube draws up the film of fluid nearest to it, and that film draws along with it the film immediately below it, and so each film drags along with it the next below, until the weight of the volume of fluid raised exactly balances all the forces which act upon it. The fact that the elevation of the water between the parallel plates is exactly _half_ that in a tube of the same diameter, clearly indicates that the force resides in the surrounding body; and the additional fact that the thickness or quantity of that body makes no difference, proves that the force resides in the surface, and that the action extends only to a very small distance.