MUSEUM OF COMPARATIVE ZOOLOGY. 



27 



Appendix. 



SECOND ANNUAL REPORT ON THE HARVARD 

 SEISMOGRAPHIC STATION. 



By J. B. Woodworth. 



The accompanying tabulated list of earthquakes and seismic 

 disturbances (pages 28-33) recorded at this Station continues the 

 list printed in the Report for the year 1908-09 (pages 30-31). 



In the record of August 13, 1908, 7 p. M. and 8 p. m. should be 

 substituted for the hours 8 and 9 respectively, according to the 

 Albany records. (Rept. 1908-1909, p. 30.) 



Altitude of Station : The elevation of the Station was provision- 

 ally determined in 1908 as 7 meters. In December, 1909, Mr. C. H. 

 Paige of the Department of Engineering accurately determined 

 the altitude of the center of the steady masses by reference to the 

 local bench marks as 5.367 meters or 17.61 feet above mean half- 

 tide. The middle of a black line painted on the south wall of the 

 instrument room has this elevation. 



Instrumental constants: The period of complete oscillation of 

 the pendulums as set up is frequently tested with the needles 

 tracing in the smoked paper. At the last determination the 

 pendulum 59A had a mean period of 25. sees; 59B 27.5 sees. 

 With these periods using the formula 



T = 2 7r I which gives 



\ Mgli 



. 4 ir Z 2 +- 

 * = ^ 2 



T2 



gl 



(i) the angle of stability for the horizontal pendulum 59 A was 

 determined to be 5'28" of arc; 59B, 9' 59.57" of arc. 



Mr. Stephen Royce in November, 1909, made the following 

 measurements of the Bosch-Omori tromometer No. 59 A. & B., to 

 which other data are appended : — 



