CONTENTS. XXlll 



for a rectangle when its upper side is in contact with the surface of the fluid, art. 

 512, pages 411 and 412. The centre of pressure determined when the plane is a 

 square, art. 513, page 412. The centre of pressure determined for a semi-paraholic 

 plane, art. 514, pages 412 and 413. Example to illustrate ditto, art. 515, pages 413 

 and 414. The same determined for one side of a vessel in the form of a parallelo- 

 pipedon, art. 517, pages 414, 415, and 416. Practical rule and example for ditto, 

 page 416. The balancing force, the centre of pressure, and the direction of its 

 motion determined for the side of a tetrahedron, arts. 518, 519, 520, and 521, pages 

 417 to 419. Example to illustrate ditto, art. 522, page 420. 



CHAPTER XV. 



OF CAPILLARY ATTRACTION AND THE COHESION OF FLUIDS. 



Capillary attraction and the cohesion of fluids, the subject introduced, with its 

 object, and remarks thereon, art. 525, pages 421 and 422. Definition of capillary 

 attraction, art. 526, page 422. Attraction of cohesion between glass and water, 

 art. 527, pages 422 and 423. The particles of a fluid attract each other, art. 523, 

 page 423. The particles of mercury have an intense attraction for each other, art. 

 529, page 423. The attraction between glass and water only sensible at insensible 

 distances, art. 530, pages 423 and 424. The manner described in which the 

 attractive influence is exerted, art. 531, page 424. The forms assumed by the 

 summit of the elevated columns described, art. 532, pages 424 and 425. The force 

 of attraction proposed to be determined, art. 533, page 425. The parts by which 

 the fluid in the tube is attracted, described, art. 534, page 426. The same as 

 respects the lower portion of the tube described, art. 535, page 426. The fluid 

 attracted by the glass only, art. 535, pages 426 and 427, A negative force in 

 the opposite direction, art. 536, page 427. The force of attraction determined, 

 and expressed by equation (310), art. 536, page 427. The conditions of the 

 rising and falling column explained, ib. The expression for the force of at- 

 traction generalized, equation (311), page 428. The height to which the fluid 

 ascends in the tube determined, art. 538, pages 428 and 429. The mean altitude 

 expressed, equation (312), page 429. The general expression modified, arts. 539 

 and 540, pages 429 and 430. The constant determined, equation (315), page 430. 

 Practical rule for the mean height, art. 541, page 430. Example for illustration, 

 art. 542, page 430. The radius of the tube determinable, art. 543, pages 430 and 

 431. The method illustrated by a numerical example, art. 544, page 431. The 

 height to which the fluid rises between two parallel plates determined, arts. 545, 

 546, and 547, pages 431, 432, and 433. The practical rule for ditto, art. 547, page 

 433. Example for illustration, art. 548, page 433. The distance between the 

 plates determinable, art. 549, page 434. Concluding remarks, art. 550, page 434. 

 When two smooth plates of glass meet in an angle, to determine the nature of the 

 curve which the fluid forms between them, art. 551 and 552, pages 435 and 436. 

 The curve determined to be the common or Apollonian hyperbola, art. 553, page 

 436. Concluding remarks, ib. Two bodies that can be wetted with water, when 

 placed an inch asunder do not approximate or recede ; but if placed a few lines 

 apart, they approximate with an accelerated velocity, art. 554, page 436. Two 

 bodies that cannot be wetted, when placed a few lines apart, approximate with an 

 accelerated velocity, art. 555, page 437. When one body can be wetted and the other 



