64 NATURAL INHERITANCE. [CHAP. 



succession of rows of pins stuck squarely into the back- 

 board, and below these again are a series of vertical 

 compartments. A charge of small shot is inclosed. 

 When the frame is held topsy-turvy, all the shot runs 

 to the upper end ; then, when it is turned back into 

 its working position, the desired action commences. 

 Lateral strips, shown in the diagram, have the effect of 

 directing all the shot that had collected at the upper 

 end of the frame to run into the wide mouth of the 

 funnel. The shot passes through the funnel and issuing 

 from its narrow end, scampers deviously down through 

 the pins in a curious and interesting way ; each of them 

 darting a step to the right or left, as the case may be, 

 every time it strikes a pin. The pins are disposed in a 

 quincunx fashion, so that every descending shot strikes 

 against a pin in each successive row. The cascade 

 issuing from the funnel broadens as it descends, and, at 

 length, every shot finds itself caught in a compartment 

 immediately after freeing itself from the last row of 

 pins. The outline of the columns of shot that accumulate 

 in the successive compartments approximates to the 

 Curve of Frequency (Fig. 3, p. 38), and is closely of 

 the same shape however often the experiment is re- 

 peated. The outline of the columns would become more 

 nearly identical with the Normal Curve of Frequency, 

 if the rows of pins were much more numerous, the shot 

 smaller, and the compartments narrower ; also if a larger 

 quantity of shot was used. 



The principle on which the action of the apparatus 

 depends is, that a number of small and independent 



