224 



These deviations and especially the progressive ones above 2000 

 atms. cannot be explained from the ternperatnre difference of 0°.l, 

 among others on account of their irregnlarity. This would give a 

 pressure difference of no more than 0.6 atm. at 2000 atms. For the 

 rest the deviations are too large and too systematical to be con- 

 sidered as accidental errors of observation. The most obvious explana- 

 tion, a systematic error in the absolute pressure measurement made 

 by Amagat or by us, cannot be accepted either, as it would yield 

 a deviation proportional for large and for small pi-essures. Probably 

 the same causes come into play, which also prevented agreement 

 between Amagat and Schalkwi.ik's observations. 



Amsterdam. Plnjsical L'lhordtonj of the Univcrsitii 



Hydrostatics. — "The different ways of floating of an homogeneous 

 cube." By Prof. D. J. Kohteweg. 



(Communicated in the meeting of May 30, 1914). 



This problem, whose treatment, however simple it may seem, 

 offers considerable difficulties, was lately brought to a complete 

 solution by Dr. P. Brandsen. 



If we limit ourselves to the cases in which the specific weight of 

 the cube amounts to less than half of that of the liquid (which is 

 allowed, because the other cases may be derived from it by inter- 

 changing the floating and immersed parts) stable floating appears to 

 be possible in four different possitions. 



In the jini position four of the edges are vertical. It may be 

 acquired for specific weights, expressed in that of the liquid, smaller 



1 1 — i 



than y/ 3 = 0,211. . . For those smaller than — = 0,16(3 . . . 



2 6 6 



it is the only one possible. 



In the second position two of the faces are vertical, but the edges 

 belonging to them are sloping. The surface section is consequently 

 a rectangle. This manner of floating is possible between the specific 

 weights 0,211 .... and 0,25. 



In the third position the space-diagonal of the cube is vertical 



and the surface section a hexagon. It is possible between the limits 



1 5 



— and — of the specific weight. F'or the limits themselves the cube 

 6 6 ^ ^ 



is lifted or immersed just so far that the surface section, perpendi- 

 cular to the space-diagonal, has passed into a triangle. Those limiting 

 positions themselves are already unstable; consequently the stability 



