AT KBW OBSERVATORY AND THEIR DISCUSSION. 



471 



TABLE XXV. Corrected Errors from later less corrected Errors from earlier of 



first 24 Experiments. 



The table shows pretty decisive evidence of a slight fall in the readings of Nos. 2 

 and 3 as time advanced. In their case the differences in the table increase on the 

 whole fairly regularly as pressure falls, a phenomenon at least consistent with a 

 diminution of true elastic moduli. With No. 4 the figures suggest a slight fall in 

 reading down to the pressure of 18 inches, but a rise at lower pressures. Both con- 

 clusions, however, are very doubtful. In only 4 of the experiments was the pressure 

 carried below 18 inches, and in the two earlier temperature averaged 5 F. higher 

 than in the two later. As we have seen in ij 22 and 23, the difference in tempera- 

 ture would tend to relatively depress the readings in the earlier experiments. Again, 

 while the entries in the last line of the table are persistently negative between 29 

 and 18 inches, they show no tendency to increase numerically as pressure falls. In 

 aneroid No. 4, as might be conjectured from Table XIX., the scale was not very 

 regular near 30 inches, so that the apparent index error, answering nominally to 

 30 inches, but in reality to a pressure which might be slightly greater, or slightly 

 Jess, was exposed to a fictitious variation, liable to influence the corrected errors at 

 lower points of the range. 



28. To throw more light on the general question, I calculated the mean corrected 

 errors shown by aneroids Nos. 2 and 3 in the years 1895, 1896, and 1897 separately, 

 confining my attention to the part of the scale most used, and including only those 

 experiments in which pressure was lowered at the normal rate. Particulars are 

 given in Table XXVI. 



TABLE XXVI. Corrected Errors, Yearly Means. 



