794 



PLATE XXXIX. 



fii;. 530. '(lie repulsive force of two piirtides of 

 maiif !■, situated at tlie distance A H or AC, is rtpre- 

 sriiled liy the oidiirates or perpeiidicularfa B I), C E, 

 i)i:uvn to tile curve T) K, supposiiic; tlie force to be 

 inversely as the distance; but the law of the force 

 appears to be uiure nearly represented by a curve like 

 1' K. The line I) I" G shows the maguitudc of the 

 cohesive force, which (ivercomc? the repiiUioii at the 

 distance A G, and is balanced by it when the particles 

 arrive at the distance A U or A 11. The dotted lines 

 represent the nature of the changes made in the lines 

 V v., I) F (i, and FH, by aii elevation of temperature. 

 P. 619. 



Fig. 531. The general direction of the cohesive force 

 acting on a particle of a liquid at A being represent- 

 ed by A B or AC, that of the repulsive force will 

 be 1) A or E A, and in order to maintain the equili- 

 brium, the forces B F and C G, making together H A, 

 must bo supplied by the pressure or reaction of the 

 internal parts. P. 620. 



Fig. 532. A. The trarsverse section of a drop, sup- 

 posed to lie of considerable length, and flatatthe sides: 

 the curvature of the outline being every where propor- 

 tional to its distance from the horizontal line A B. 

 B, a round drop, the concavity at the horizontal line 

 being equal to the convexity which would be found 

 by cutting oft' the drop horizontally; the sum or differ- 

 ence of the curvatures being every where proportional 

 to the distance from this line. P. 621. 



Fig. 533. The solid AB possessing }ialf the attrac- 

 tive power of the liquid CD, the surface of the liquid 

 will remain horizontal : for the attractions will be re 

 presented by D A, DE, and D C ; and of these D A 

 and D E make D B, and D B and D C make D F, which 

 IS in a vertical direction. If the solid be more attract- 

 ive, the forces will be combined nearly as at G, and 

 if less attractive, as at H. P. 622. 



Fig. 534. The form of the surface of a liquid in 

 contactwith a pl.ane and vertical side of a solid which is 

 wetted by it. The height of the ascent of water is about 

 one fourth of that which is here represented. P. 622. 

 Fig. 535. The form of the surface of a liquid clerat- 

 ed between two plates which meet at A, and are at a 

 little distance from each other at B ; about one third 

 of an inch, supposing the liquid to be water. P. 623. 

 Fig. 536. The height at which water will stand in 

 tubes of the form and magnitude which arc here re- 

 presented. P. 623. 



Fig. 537. The depression of niorcury, in contact 

 witli a large or Hat glass vessel, is one fourth as great 

 as that which is here represented. P. 623. 



F'ig. 533. The depresKion of mercury within a small 

 tube of glass. P. CV3. 



Fig. 530. The actual elevation of a portion of water 

 In contact with a horizontal surface which is wetted 

 by it. P. 624. 



Fig. 540. The elevation of mercury in contact with 

 a horizontal surface of glass. P. 624. 



Fig. 541. A, a wide drop of water standing on a dry 

 surface, not attracting it. B, a wide drop of mercury, 

 staiidhig on glass. P. 624. 



Fig. 512. A magnified representation of the man- 

 ner in which the seeds of lycopodium prevent a drop 

 of water from wetting the substance od which it stands. 

 P. 624. ; 



Fig. 543. The bodies A and B, and the bodies C 

 Snd D, appear to attract, and E and F to repel each 

 other. P. 625. 



Fig. 544. The apparent cohesion of two plates, be- 

 tween which a fluid is interposed. P. 625. 



Fig. 545. The apparent attraction of adrop between 

 two plates, tending to draw it towards the line of their 

 junction, causes the drop to rest in an inclined posi- 

 tion of the plates. P. 625. 



Fig. 546. Dr. Ilerschel's figure, representing by tlie 

 distance of the curve ABC from the line .\ C the heat 

 thrown on different parts of A C by a |irism, while DC 

 ii the illuminated part, divided according to Newton's 

 experiments, tbr quantity of light being expressed by 

 the distance of the line D E C. P. 639. 



Fig. 547. Dr. Ilerschel's figure of the distribution 

 of heat and light corrected ac«ording to the division 

 of the coloured spectrum, as ascertained by Dr. Wol- 

 laston. P. 639. 



Fig. 548. Bernoulli's air thermometer. P. C50. 

 Fig. 549. A differential air thermometer, or tliermo- 

 scope, from which the pressure of the atmosphere is 

 excluded. From Kunze. P. 650. 



Fig. 550. A differential thermometer on Mr.,Leslie's 

 construction. P. 650. 



Fig. 551.The distribution of the electric fluid in spheres 

 of different sizes, and at different distances, and in a 

 conical point. The density is represented by the dis- 

 tance of^the dotted line from the surface. P. 603. 



