108 THE ACQUISITION OF SKILL IN ARCHERY. 



chief object of this experiment was to test the value of the method and to work 

 out the technique of experimentation, but the range of the experiment was 

 extended to include a comparison of the rate of improvement in two groups 

 of men differing in certain respects, to be considered later. The writer acted 

 as subject and assisted in conducting this experiment. During the spring 

 of 1914 the range described below was constructed on the grounds of The 

 Johns Hopkins University and the experiments were continued in a study of 

 the relation of the rate of improvement to the distribution of practice. 



I wish to express my very great indebtedness to Professor Watson for the 

 unrestricted use of the data obtained at the Tortugas, for the main features in 

 the design of the apparatus employed in the later work, and particularly for 

 his generous advice and assistance throughout the experiments. 



My thanks are due also to Dr. Alfred G. Mayer for his interest in the work 

 and for permitting his laboratory staff to devote their time to it. 



Finally, I owe a great deal to the people who have taken part in the experi- 

 ments, particularly to those in the "5-shot group," whose regular practice for 

 many weeks was carried out at no small inconvenience to themselves. 



EQUIPMENT. 



The equipment used in the Tortugas experiments consisted of bows, arrows, 

 target, screen to mark the results of wild shots, and a shield for the experi- 

 menter near the target. The arrows were of good quality, 28 inches in length. 

 The bows were of lemon wood, 6 feet in length, and requiring a pull of 44 

 pounds to draw the arrows to the head. An arrow properly discharged from 

 such a bow will pierce a half-inch pine board at a distance of 40 yards and 

 has an almost flat trajectory for that distance. The target was the official 

 48-inch target of rye straw faced with white canvas, on which was painted a 

 10-inch black bulls-eye. It was mounted on a metal tripod so that the center 

 of the bulls-eye was 4 feet from the ground. 



The length of the range used in all the experiments was 40 yards, at which 

 distance the bulls-eye subtends a visual angle of 33'. The target was set up 

 at the foot of a sand-bank, which served to stop the arrows passing the target. 

 As beginners rarely hit the target at this distance, some method of recording 

 the distance of wild shots from the bulls-eye was necessary. For this purpose 

 a muslin screen, 14 feet square, was erected around the target. The arrows 

 made holes in the cloth and the distance from these to the center of the 

 bulls-eye was taken as the record of the shots. This made it necessary to 

 measure each shot as soon as it was fired, a method which proved neither 

 convenient nor safe. 



The method employed in the first experiment was the following: The sub- 

 ject was given instruction by word and example of the method of nocking, 

 drawing, and loosing the arrow, but was told nothing of the method of aiming, 

 the choice of a point of aim, or the general bodily position in aiming and loosing. 

 He had to find out for himself how to ami, to prevent the bowstring from 

 catching on his clothing or arm, to allow for the curve of the arrow's trajectory, 

 to counteract the kick of the bow by increased tonus of the flexors of the left 

 arm, together with the large number of finer details which make for accuracy. 

 After the first instruction he was given a bow and 12 arrows and sent to a 

 point 40 yards in front of the target, where he stood alone and loosed the arrows 



