74 



THE ART OF PROJECTING. 



Fig. 55. 



figure, and such ratios as 2 to 3 (do to so/\ and 3 to 4 

 (do to fa), may be known by their representative figures, 



Fig. B6. 



55 and 56. The ratio i to 3 (do to sol, in next octave,) 

 will present such forms as those in Fig. 57. 



Fig. 87. 



In any case, the figure will remain constant when the 

 ratio is exact, and the ratio may be known by counting 

 the number of loops upon the top and one side. Thus, 

 in the fully developed figure, with the ratio 2 to 3, there 

 may be counted two loops upon the top and three loops 

 upon the side, which indicate that the fork that vibrates 

 horizontally makes three vibrations, while the other one 

 makes two. 



The overtones may be developed and exhibited upon 

 each of these compound forms by striking upon the 

 fork rather lightly, about midway of its length, while it 

 is giving any particular figure. Thus, if the forks are 

 in unison and a circle has been obtained, the overtone 



