IOWA ACADEMY OP 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 v\^hich 
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 
