ICE, HOT. 



405 



a ball heavier than the liquid be substituted 

 for the cork, attraction ensues, presenting an 

 analogy to paramagnetism. The explanation of 

 these effects is that, in the first case, the oscil- 



FIG. 2. 



lations of the cork are greater than the water, 

 and are hence relatively in the same direction, 

 while in the latter case the movement of the 

 ball is less than that of the water, and conse- 

 quently, relatively to it, opposite in direction. 

 These effects are very clearly shown by an ap- 

 paratus in which a rod of cork and one of metal 

 are immersed in the liquid. On bringing near 

 to them a vibrating drum the cork sets itself 

 eqnatorially, and the metal rod axially. 



By a very simple piece of apparatus, illus- 

 trated in Fig. 3, Dr. Bjerknes succeeded in re- 

 producing the well-known magnetic curves 

 taken by iron filings when brought near the 

 pole of a magnet. To do this he mounted a 

 cylinder or sphere upon a spring and affixed to 

 its upper part a fine paint-brush. When the vi- 

 brating drums or spheres were caused to move 

 in the neighborhood of this, it was thrown 

 into vibration, and its movement traced by the 

 brush upon a glass plate placed above. In this 

 way the curves for all the different vibrations 

 are graphically depicted. With two drums pul- 

 sating concordantly the figure is exactly like 

 that assumed by iron filings ha a field of two 



similar magnetic poles, while, when they are 

 discordant, the figures are those of two unlike 

 magnetic poles. 



As the outcome of these experiments and his 

 mathematical analysis, Dr. Bjerknes considers 

 magnetism to be a rectilinear vibration instead 

 of a kind of molecular rotation, as physicists 



have been wont to regard it. On this view an 

 electric current would be a circular oscillation, 

 the direction of the current being the axis of 

 oscillation. The experimental illustrations of 

 the effects of a current are much more difficult 

 than those of magnetism, as there are required, 

 instead of bodies in vibration, bodies in alter- 

 nating rotation, and so far but a few of the 

 more simple ones have been made. It was found 

 necessary, to produce friction enough, to use 

 a viscid fluid instead of water, which introduced 

 various difficulties hard to overcome. Tracings 

 of the figures produced by his moving bodies 

 were, however, obtained and found to agree 

 exactly with those produced on a glass plate by 

 iron filings in the neighborhood of electric 

 currents. Dr. Bjerknes is still occupied with 

 carrying on his mathematical investigations, 

 and devising means for their experimental dem- 

 onstration. Such studies can not but be of the 

 greatest value, as giving clear ideas of thfe 

 mechanism of electric action. 



ICE, HOT. Professor Thomas Carnelly has 

 discovered that ice and other bodies under ex- 

 ceedingly low pressures will not pass into the 

 liquid state, but remain solid when the tem- 

 perature is raised far above their melting- 

 points, and then vaporize directly. Water was 



congealed in thin layers about a thermometer- 

 bulb in an ample Torricellian vacuum, and on 

 the sides of the vessel, in which the pressure 

 did not exceed 1-0 to 1'5 millimetre. The ves- 

 sel was a tube of glass, inclosing the thermom- 

 eter, and communicating with a bottle above 



