An Improved Harmonograph. 
63 
by two of these harmonographs combined in a manner somewhat 
analogous to that employed in Donkin’s harmonograph for com¬ 
pounding two motions. Let two harmonographs be so placed 
that their recording rods, when in their central positions, meet 
and form the same straight line, this line preferably being ver¬ 
tical; and let an additional shaft with a gear upon each end con¬ 
nect the driving wdieels of the tw T o machines. If now the lower 
recording point be replaced by a tablet moving freely upon ways 
transverse to the line of the recording rods, these ways being 
part of a carriage itself movable upon ways transverse to the 
first ways and also to the line of the recording rods, the desired 
resultant of three or four harmonic motions having any relative 
directions, amplitudes, periods and epochs w T ill necessarily be 
shown. 
Ripon, Wis. 
