284 PROCEEDINGS OF THE AMERICAN ACADEAHT 



merely locked by the atmospheric current, without furnishing 

 means of observing its direction. Fortunately, the current 

 gives opposite results on Bain's prepared paper when travers- 

 ing it in different directions. In the specimens exhibited, the 

 paper was seen to be marked with deep blue lines, where 

 the wire pen-point had been the negative pole of the atmos- 

 pheric current, and the slightly blue paper was seen to be 

 bleached when it had been the positive pole. 



The most remarkable exhibition, however, was in the burn- 

 ing of the paper in several places in the track of the pen-point, 

 and for distances corresponding to several minutes of time. 

 This is probably the most continuous and extensive exhibition 

 of atmospheric electricity in connection with the aurora on 

 record. The aurora itself, on the 29th of September, was a 

 very remarkable display. It is to be regretted that precise and 

 comparative observations were not made upon the Bain wires 

 proceeding in different directions from this city. The phe- 

 nomena, however, on the New York and Burlington lines 

 seem to have been identical. 



Dr. A. A. Gould, exhibited a specimen of a new method of 

 electrical telegraphic recording. 



Professor Guyot exhibited an interesting experiment, de- 

 vised by Professor Snell, to show the motions of water con- 

 tained in a tall glass jar, when made to rotate with various 

 degrees of velocity, by means of four flat metallic radii at- 

 tached to the lower extremity of a vertical axis, and situated 

 a little above the middle of the jar. Assuming the motions 

 of the water in this experiment to be essentially similar to 

 those of the air in a tornado, he proceeded to explain many 

 of the phenomena of the late tornado in Middlesex County. 

 He was of opinion that a whirlwind was produced by the 

 conflict of opposite winds at a considerable height above the 

 ground, and that warm air from below and cold air from above, 

 rushing towards the centre of the vortex, caused by their 

 mixture the formation of snow and hail. 



He also stated reasons for supposing that the apex of the 



