764 



SCIENCE. 



[N. S. Vol. II. No. 49. 



age weight of men may be 150 pounds, and 

 there are men weighing 300 pounds, but 

 none weighing 0. In actual measurements 

 it is probable that large positive errors 

 occur more frequently than negative errors 

 of the same size. 



When students were asked what was 

 said during the first two minutes of the lec- 

 ture in the same course given one week be- 

 fore, the accounts were such that the lec- 

 turer might prefer not to have them re- 

 corded. From the testimony of the stu- 

 dents it would appear that two minutes suf- 

 ficed to cover a large range of psychological 



times, but the average estimate of 4,022 had 

 an average variation of 2,669 times. It 

 might be supposed that the number of times 

 was in any case sufiicient to impress a tol- 

 erably exact recollection of the hall, but 

 the drawings vary to such an extent that 

 any one taken at random would be likely 

 to give an entirely false impression. An 

 examination of the many drawings, how- 

 ever, leaves on the mind a fairly exact idea 

 of the hall, and it would be possible to 

 make a composite drawing which would be 

 found to approach a correct ground plan. 

 Three of the ground plans (supposed to be 



Ground-plans of a hall drawn from memory (scale 1:96). 



and other subjects, and to make many 

 statements of an extraordinary charac- 

 ter. 



The last task set was to draw in a scale 

 of about \ inch to the foot a ground plan of 

 the entrance hall of the building in which 

 the class met, ten minutes being allowed. 

 The students were also asked to state 

 about how many times they had passed 

 through the hall. All the students (with 

 some possible exceptions) had passed 

 through the hall about an equal number of 



drawn on the same scale and here reduced 

 about one-half) are subjoined. This is 

 worth the while if only to emphasize the 

 worthlessness of many hundred casual ob- 

 servations as compared with one meas- 

 urement. 



Psychology is continuallj' gaining ground 

 as a natural and even as an exact science, 

 and some progress is made when in any 

 direction the surmise of daily life is super- 

 seded by systematized facts and measure- 

 ments. 



