ON SEISMOLOGICAL INVESTIGATION. 179 



Nov. 3. East motion 5 A.M. to 2.30 p.m., west motion 2.30 p.m. to 6 P.M. 



Amp. 4 mtn. Dull. N. wind. 

 „ 4. East motion 10 a.m. to 3 p.m., west motion 3 p.m. to 7. .SO p.m. 



Amp. 8 mm. Fine. N. wind. 

 „ 5. East motion 8.30 A.m. to 3 p.m., west motion 3 P.M. to midnight. 



Amp. 10 mm. Fine. E. wind. 



The greatest movements have been on the fine days. 



Tremors were observed on October 30, 3 to 17 hours, of 2 mm. range, 

 and slight tremors on October 31 and November 4. 



Three displacements were noted which do not agree with the records 

 of T, but the earthquakes Nos. 55 and 59 shown by T were well recorded. 



10th week {Nov. 6-13.) :— 



Nov. 6. East motion from before noon to 2.30 p.m., west motion 2.30 to 



8 p.m. Amp. 7 mm. Fine. N. wind. 

 „ 7. East motion 6.30 a.m. to 3.0 p.m., west motion 3 to 6 p.m. Amp. 



1 mm. Fog, frost. 

 „ 8. No wave, but westerly displacement midnight to 7 A.m. Eain. 



N. wind. 

 „ 9. East motion from before noon to 2.45 p.m., west motion 2.45 to 



8 P.M. Amp. 7 mm. Fine. N. wind. 

 „ 10. East motion 9 A.m. to 3.30 p.m., west motion 3.30 to 7 p.m. Amp. 



6 mm. Fine. Calm. 

 „ 11. East motion from before noon to 2 p.m., west motion 2 to 6 p.m. 



Amp. 1 mm. Dull. W. wind. 

 „ 12. East motion 9 A.M. to 3 p.m., west motion 3 to 6 p.m. Amp. 8 mm. 



Dull. S. wind. Afterwards fine. 



The diurnal wave is evidently pronounced on fine days, and small or 

 absent when it has been rainy, cloudy, or dull. 

 Tremors were noted as follows : — 



Nov. 6. 4 to 12 hours. Slight. 



„ 7. 7 to 22 „ Maxima of 2 mm. at 19 hours. 

 „ 9. 4 to 12 „ „ 1 mm. at G hours. 



„ 10. 6 to 11 „ „ 1 „ 



„ 11. 18 to 20 „ „ 5 „ 



„ 12. 4 to 13 „ „ 1 „ 



Six small displacements were noted, which do not agree with the records 

 of T. 



The Diurnal Wave. 



Figure 1 6 shows half-size tracings of daily waves taken from the origi- 

 nal photograms. Angular values for these waves may be approximately 

 obtained by assuming that 1 mm. deflection corresponds to a change 

 in inclination of 0'5 sec. of arc. Should accurate measurements of these 

 quantities be required, they can be obtained from my note-books. 



Days on which the diurnal wave was very small have been omitted. 

 The curves which are given clearly show that the daily deflection is 

 variable in amount ; but whether the ground around the tent was open, or 

 covered by a tarpaulin on the west side or on the east side, the times at 

 which the pendulum commenced, completed, and ended its sharper 

 movements are practically the same. If we commence in the morning, 

 the direction of movement of the pendulum from a north-south line, 

 or its normal position, was such that it tended to approach a position that 

 would place its boom in a line with the sun and the shadow of the tent. 

 That is to say, it swung towards the east, but it continued this motion 



N2 



