UPON GASES AND LIQUIDS. 569 



35. The magnetic action exerted upon the hquid is more ap- 

 parent when the quantity of the latter is diminished. When its 

 circumference originally formed a circle of 25 millims., this, 

 viewed from above, extended itself, becoming narrower in the 

 axial and broader in the equatorial direction, into a more ex- 

 centric ellipse, the axes of which were 30'5 millims. and 13 

 millims. (PI. IV. fig. 8). The axial section of the liquid, in the 

 direction A B, is represented in fig. 8 a ; the equatorial, in the 

 direction C D, in fig. 8 b. 



The upper angles of the two halves of the keeper upon which 

 the watch-glass stands are indicated in figs. 8 to 12 by the two 

 arcs of larger radii. 



56. When the shortest distance apart of these two halves of 

 the keeper was increased to 8 millims., the form of the fluid, the 

 amount last used being retained, was very essentially altered. 

 When viewed from above, it formed (PI. IV. fig. 9) an oval 

 figure, which deviated considerably from an ellipse. Its dimen- 

 sions in the equatorial plane remained the same, but in the 

 meridional plane the fluid had contracted to 14"5 millims. Fig. 



9 a and fig. 9 b represent the sections of the fluid in the dii-ections 

 of A B and C D respectively ; both are bounded above by almost 

 straight lines. 



37. The quantity of fluid remaining the same, the poles were 

 separated 15 millims. from each other; the form given in fig. 10 

 then resulted, by the contraction of the original circle in the axial 

 as also in the equatorial direction ; in the former the convexity 

 of the circle was diminished, in the latter it was changed in the 

 centre into a concavity. The new boundary curve came into 

 contact with the above circle, by which it was completely en- 

 closed, in those four points through the perpendicular projection 

 of which the upper angles of the two halves of the keeper passed. 

 Viewed from above, two elevated ridges w'ere seen ; these coin- 

 cided with two right lines, the projections of which were in con- 

 tact with the angles of the halves of the keeper at those points 

 where they were least separated ; and in the centre betweenth e 

 two a depression running parallel with them and situated in the 

 equatorial plane. The two sections of the liquid in the direc- 

 tions of A B and C D, in the instance described in the preceding 

 jjaragraph, were here so changed that the former (PI. IV. fig. 



10 a) acquired a depression in the centre, and tlie latter (fig. \0 b) 



VOL. v. PART XX. 2 Q 



