74 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



the angular velocity, but it is evident that in the case here considered 

 the resistance does not nearly follow this law. We may notice that 

 according to Poisson's rather rough approximation, HT and CL 

 would be straight lines. 



TIME. 



Figure A. 



III. A new suspended system was then made of two 15 millimeter 

 long magnetic needles mounted horizontally, one over the other 

 (together with a small mirror), on a short bit of glass fibre stretched 

 between two short lengths of No. 36 steel wire. The restoring forces 

 came from the torsional forces in these wires. The mirror and needles 

 together exposed to the air a resisting surface of less than a square 

 centimeter area. The period was about l/48th of a second. The 



