54 



/. M. Baldwin : Standard Yard Measures. 





Sta 



,nda 



rdat 



Length 



at 62° F. 



Difference.. 



Bar. 



Orijfinal. 



Present. 



Original 



Present, 

 in 



P-0. 

 ill 



18 



62-26° F. 





62-36 F. 



1 yd. - -00009 



1 yd. -00012 



- -00003 



40 



61-99 





61-89 



+ 



+ 4 



+ 4- 



. 37 



62-07 





61-32 



2 



+ 23 



+ 25 



1383 



57 





66-4 



+ 171 



- 150 



- 321 



The changes shown in bars (18) and (40) are quite prob- 

 able. The change in bar (37) can be explained by the fact 

 that pointings in the present series had to be made on a small 

 part near the end of one of the terminal lines, instead of mid- 

 way between the two longitudinal lines. The difference in bar 

 (1383) is altogether too large to be explained by a change in 

 the length of the bar. The most probable explanation is that in 

 the original comparison a mistake was made in the sign of the 

 correction — that the bar, instead of being too long, as shown 

 on the certificate, was in reality too short. This would assume 

 that the temperature of comparison was 6L7°F., a quite likely 

 temperature. 



