Putnam— Results of Pendulum Observations. 187 



and brought back to Austin, where early in June it was set up 

 in the basement of the State University, somewhat more ele- 

 vated and to the northward of the Capitol. Here two com- 

 plete and independent sets of observations were carried out, 

 with the pendulums swinging in the prime vertical in the first 

 set and in the meridian in the second set. After applying a 

 correction to the Capitol observations to reduce to the eleva- 

 tion and latitude of the University, the corrected periods were 

 found to be : — 



Pendulum A4. Pendulum A5. Pendulum A6. Mean. 



Capitol-. -5010508 ?: 5008777 S; 5008407 ~ : 500923L 



University, prime vertical, 10508 8784 8417 9236 



University, meridian 10504 8784 8424 9237 



A comparison of the last two results indicates, as was 

 anticipated, that the position of the planes of oscillation with 

 respect to the meridian has no effect on the period. 



Favorable locations, always in basements of buildings, were 

 found for the observations at the other stations also, with the 

 exception of New Orleans. At Laredo the instruments were 

 in the commissary of Fort Mcintosh, at Galveston and Calais 

 in high-school buildings, and at New Orleans in the City hall. 

 The necessity of being near the longitude station compelled 

 this location in the latter place, though on account of close 

 proximity to a heavily travelled street and the unstable nature 

 of the underlying ground it was unfavorable, as the jar of pass- 

 ing vehicles was quite noticeable. The coincidences were some- 

 times irregular, but the periods of the three pendulums are in 

 good accord and no discrepancy appears between the day and 

 night observations. 



The following table gives a summary of the results for 

 these stations, the relative values of gravity being based as 

 before on that provisionally adopted for Washington, and the 

 computed values being derived from a theoretical formula 

 depending on Clarke's figure of the earth (1880). The observed 

 values have been reduced to sea level by two methods, first 

 JBouguer's, in which the attraction of the entire mass above 

 sea level is subtracted, and second, Faye's, in which in the 

 attraction term only the difference from the average surrounding 

 elevation is allowed for (in this case the average within a radius 

 of 100 miles has been estimated as before). The usual elevation 

 and topographical corrections are of course included in both of 

 these methods. The residuals observed minus computed grav- 

 ity are given in the table for these two methods of reduction 

 to sea level. 



