IOWA ACADEMY OF SCIENCES. 45 



UNIT SYSTEMS AND DIMENSIONS. 



T. PROCTOR HALL. 

 (Abstract.) 



[Published in full in Electrical World February 7, 1896.] 



The three fundamental units of the C. G. S. system are 

 reduced to two when the unit of mass is defined as the quantity 

 of matter which, by its gravitational force, produces at unit 

 distance unit acceleration; and these two to one when the unit 

 of time is defined as the time taken by an ether wave one cen- 

 timeter long to advance one centimeter. A table is given show- 

 ing the dimensions of units in each of these three systems, and 

 the advantages of the latter are pointed out. 



A MAD STONE. 



BY T. PROCTOR HALL AND ERNEST E. FRISK. 



Here and there is found a man possessing a pebble for which 

 he claims the remarkable power of preventing hydrophobia 

 when applied to the wound made by a mad dog. We have been 

 unable to find any record of a scientific examination of a mad 

 stone or a scientific test of its properties. This may be partly 

 accounted for by the rarity of the stone, and the high esteem in 

 which they are held by their owners. A popular idea is that 

 they are formed by accretion in a deer's stomach. 



Last summer while visiting the Mammoth Chimney mine, 

 eighteen miles south of Gunnison, Col., a prospector called 

 attention to some small pieces of light- colored rock from the 

 mine, which adhered very strongly to the tongue. Some 



