BOOK ilJ conspicuous instances. 487 



iiibstance of the water. So eaves* droppings, if tliere be enough 

 water to follow them, draw themselves out into a thin thread, not 

 to break the continuity of the water, but if there be not enough 

 to follow, the water forms itself into a round drop, which is the 

 best form to prevent a breach of continuity ; and at the moment 

 the thread ceases, and the water begins to fall in drops, the 

 thread of water recoils upwards to avoid such a breach. Nay, in 

 metals, which when melted are liquid but more tenacious, the 

 melted drops often recoil and are suspended. There is some- 

 thing similar in the instance of the child's looking-glass, which 

 little boys will sometimes form of spittle between rushes, and 

 irhere the same pellicle of water is observable ; and still more in 

 ihat other amusement of children, when they take some water 

 rendered a little more tenacious by soap, and inflate it with a 

 pipe, forming the water into a sort of castle of bubbles, which 

 assumes such consistency, by the interposition of the air, as to 

 admit of being thrown some little distance without bursting. 

 The best example is that of froth and snow, which assume such 

 consistency as almost to admit of being cut, although composed 

 of air and water, both liquids. All these circumstances clearly 

 show that the terms liquid and consistent are merely vulgar 

 notions adapted to the sense, and that in reality all bodies have 

 a tendency to avoid a breach of continuity, faint and weak in 

 bodies composed of homogeneous parts (as is the case with liquids), 

 but more vivid and powerful in those composed of heterogeneous 

 parts, because the approach of heterogeneous matter binds bodies 

 together, whilst the insinuation of homogeneous matter loosens 

 and relaxes them. 



Again, to take another example, let the required nature be 

 attraction or the cohesion of bodies. The most remarkable con- 

 spicuous instance with regard to its form is the magnet. The 

 contrary nature to attraction is non-attraction, though in a similar 

 substance. Thus iron does not attract iron, lead lead, wood 

 wood, nor water water. But the clandestine instance is that of 

 the magnet armed with iron, or rather that of iron in the magnet 

 80 armed. For its nacure is such that the magnet when armed 

 does not attract iron more powerfully at any given distance than 

 when unarmed ; but if the iron be brought in contact with the 

 armed magnet, the latter will sustain a much greater weight than 

 the simple magnet, from the resemblance of substance in the two 

 portions of iron, a quality altogether clandestine and hidden 

 m the iron until the magnet was introduced. It is manifest, 

 therefore, that the form of cohesion is something which is vivid 

 and robust in the magnet, and hidden and weak in the iron. It 

 isto be observed, also, that small wooden' arrows without an'irdn 

 point, when discharged from large mortars, penetrate further 

 mto wooden substances (such as the ribs of ships or the like), 



