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Intelligence and Miscellaneous Articles. 



been at rest. The particles of water in the plane of symmetry 

 between the falling spheroids remain at rest. 



Instead of two spheres, one may be allowed to fall near a plane 

 vertical wall, which then acts as plane of symmetry. The spheroid 

 falls as it were with its image in the plane vertical wall, and 

 approaches and recedes from this. 



These experiments with heavy oil spheroids in water are tedious, 

 and can only be shown to a small audience. 



Analogous phenomena may be produced before a larger circle of 

 hearers by allowing two soap bubbles filled with coal-gas to ascend 

 near each other, or a single bubble near a vertical wall. 



In ascending, the distance of the two soap bubbles from each 

 other, or of a single one from its image in the vertical wall, is first 

 smaller and then greater, and the cause again is the vortex move- 

 ments in the air due to the ascending soap bubbles. 



In order to fill two soap bubbles simultaneously with coal-gas 

 they are produced at the ends of a T-piece of glass, blown out 

 in the form of horizontal cups, to which the gas passes from the 

 centre tube through a T-shaped perforated glass stopper. 



Similar phenomena occur when small dust particles fall in air or 

 liquid at rest, or if a current of air or liquid strikes against 

 particles of dust at rest. The motion of the small particles is 

 influenced by the presence and form of the solid wall in the 

 vicinity. — "Wiedemann's Annalen, July 1894. 



ON A NEW APPARATUS FOR THE PRODUCTION OF HIGH PRESSURE. 

 BY PROF. S. W. STRATTON*. 



Not long since, while designing a piece 

 of apparatus for the production of high 

 pressure, it occurred to me that many of 

 the difficulties encountered in the measure- 

 ment of such pressures might be avoided by 

 the employment of several short mercury- 

 columns connected in series by means of a 

 less dense liquid, as shown in the accom- 

 panying sketch. 



Such a gauge would possess all the advan- 

 tages of the ordinary mercury-column, and 

 be within the limits of space to be had in the 

 laboratory. For many purposes the last tube 

 only need be made of glass, and the scale 

 reduced accordingly. 



Thinking that this principle may be new, 

 and of value to some who are employing 

 high pressures in the laboratory, it is sub- 

 mitted for publication. 



U 



I 



The Ryerson Physical Laboratory, 



University of Chicago, 



May 21, 1894. 



* Communicated by Prof. A. A. Michelson. 



