144 VITALITY AND EFFICIENCY WITH RESTRICTED DIET, 



12-point. The digits 1 and were not employed, and an effort was 

 made to avoid combinations which added to 10. Each digit was used 

 with approximately the same frequency in the material taken as a 

 whole, as is seen in figure 19, the blocks being arranged in 10 columns, 

 each containing 10 digits. A page was composed of 8 of these blocks. 

 Six different pages of such material were prepared. 



The printed forms were set up on a linotj^pe machine, each horizon- 

 tal line of digits being a separate linotype slug. One hundred of these 

 slugs were made up and numbered with a punch. They could thus be 

 readily combined into an indefinite number of blocks of addition 

 material. This method made a substantial saving in the cost of com- 

 position. 



The procedure followed in the test was to begin adding the 10 vertical 

 columns in the upper left-hand block of material, placing the sums 

 below. When the 10 columns had been added, the subject added the 

 same material, but in the horizontal lines, so a block of 100 digits in the 

 form shown in figure 19 provided 20 lines of addition. The method of 

 adding, and of entering the sums, is shown in figure 20. The subjects 

 were told that they had 10 minutes for the addition. No clock or 

 watch was visible and no warning signal given until the signal to stop. 

 The time interval was measured with a stop-watch. The men were 

 instructed to work as swiftly and accurately as possible. Equal em- 

 phasis, so nearly as may be judged, was placed on both factors. Par- 

 ticular attention was called to the most frequent types of errors in 

 addition. The attention of the subject was also frequently directed to 

 the ease with which numbers may be transposed in writing them down. 

 The greatest care was taken to maintain silence in the room. The men 

 worked on the honor principle, and without exception they worked in 

 this adding test very silently and intensely (at least so far as could be 

 judged from facial expressions and physical attitude). 



There is no precedent at hand for using horizontal lines of digits in a 

 test of adding efficiency. The method suggested itself as an economical 

 expedient to minimize movements, such as shifting of paper and posi- 

 tion. Preliminary trials with other subjects did not disclose any par- 

 ticular difficulties in adding digits arranged horizontally when the 

 material was spaced as it is in figures 19 and 20. It must be noted that 

 in printing from Unotype slugs the horizontal columns always remain 

 the same, a particular horizontal column being subject to shift from one 

 block to another and to different position in a block of such digits, but 

 the sum of it being always the same wherever it is. No information as 

 to the method of makeup of the blanks was given the men. They 

 never saw the forms except at the 10-minute test periods. They did 

 not know how many different blanks existed, as these were designated 

 from each other by a secret mark, which was the digit in the extreme 

 lower left-hand corner. It is hardly likely that under these circum- 



