520 



SCIENCE 



[N. S. Vol. LIII. No. 1379 



In this example, since the earlier date (March 

 23) precedes the later date (September 17) within 

 the same calendar year, P in step (6) lies within 

 the sector extending clockwise from index a to 

 index 6. If the later date precedes the earlier 

 date on scale B, P lies outside the sector similarly 



formed, and 1 must be subtracted from the num- 

 ber of years indicated in step (5). Thus, in the 

 following example — an unusual case involving all 

 the steps heretofore described — 



Example: What is the age on March 3, 1920, of 

 an individual born July 16, 1873? 



In step (3) it is seen that F lies outside the sec- 

 tor extending clockwise from index a to index h 

 and accordingly 1 is subtracted from the reading 

 in step (5). In step (2), correction is made for 

 the occurrence of February 29 in the interval, and 

 by steps (7) and (8) is obtained the correct read- 

 ing of days in the remainder of the reading in 

 months (step 6). The age, then, is found to be 

 46 years, 7 months, 16 days. 



(c) To determine the period of liability in in- 

 dustrial insurance: 



A new index (a') may be marked on scale A at 

 a point representing, in the counter-clockwise di- 



Scale A. | 



reetion from index a, the number of days in the 

 legal interval between the date of injury and the 

 first day of compensation. For example, in Massa- 

 chusetts, where compensation starts on the 15th 

 day of incapacity, index a' is marked at 351. 

 With the day of injury (scale B) set at index a', 

 the number of days of compensation may be read 

 directly on scale A at the day on scale B repre- 

 senting the date of termination of disability. 



Example: For what number of days shall com- 

 pensation be paid to an employee injured on April 

 9 and incapacitated until August 5t 



I (3) At P, read 104 days (or 14 weeks, 6 days). 



Scale B. 



(1) Set P at Aug. 5. 



(d) To find the decimal fraction of a year 

 equivalent to a given number of days. 



1 (2) At index a' (351), set April 9. 



Example: What per cent, of a year is an in- 

 terval of 211 days! 



, Or, to find the number of days equivalent to a 

 decimal fraction of a year: 



Example: What is the eqmvalent in days of .Zt 

 year? 



