and the Glolular Form of Fhiids. 349 



filings, are of this description. These curves in the air 

 continually endeavour to bring the two ends of the com- 

 pass-needle together, to form a magnetic circuit by a more 

 direct communication ; and it is the predominant force of 

 these curves, when their equilibrium is destroyed by the 

 interposition of a magnet, that gives motion to the needle 

 in obedience to its distant force. 



These curves, or rather curves formed upon this prin- 

 ciple, which can only give motion to the solid needle as a 

 whole, acting in the same manner, produce the actual 

 union of the unconnected surfaces of a line of fluid par- 

 ticles, such as are described in the figure, by bending the 

 line so that the two ends may meet. 



All bodies having polar forces are disposed to unite 

 their terminating surfaces in this manner, and would do so 

 if they had freedom of motion. But there is a force op- 

 posed to it, even in fluids ; and it arises from the position 

 of the poles, which being opposite to each other upon the 

 several atoms, disposes the particles to form right lines ; 

 when, therefore, the line is bent so that its two ends may 

 be united, this force brings it into a circle by the equality 

 of its resistance. It is, in fact, in the state of an elastic 

 rod, the two ends of which are brought together; and the 

 forces that give to both a circular form are similar. 



The union of circles of particles formed in this manner, 

 which intersect each other upon the principle we have 

 already described, produces globules, or drops; and it is the 

 same arrangement, which is liable to unlimited increase from 

 concentric layers of particles, that gives the rounded form 

 to fluids generally, when they are not attracted by the con- 

 taining vessel, and which is more particularly observable 

 in mercury, and other metals when reduced to a fluid state 

 by fusion ; the latter case differing from the former, only 

 in the flattened form of the larger quantity by the force of 

 gravitation, from which globules are exempted by the 

 greater force required to bend the lines which form their 

 surfaces; upon the same principle that a rod of great 

 length in proportion to its elastic force will bend by its 

 own weight, when formed into a circle and placed in a 

 vertical position ; whereas a small part of the same rod, 



