118 REPORT— 1895. 



of concrete covering a bed of gravel rammed into the natural earth. It 

 was covered by a coarse wooden case. The whole arrangement was shel- 

 tered by a small wooden hut, 9 feet long and 7 feet broad, and up to the 

 eaves 6 feet in height. This hut, like all the other huts, admitted so much 

 light that the photographic tilms had to be changed at night. Currents of 

 air came in freely, and, as might be expected, there were considerable 

 fluctuations in temperature. 



On the west side the ground was flat and open, and it was also fairly 

 open towards the north and south. On the east side, however, it was 

 sheltered by a small hill and trees, behind which came a pond, more trees, 

 and then instrument K, which had a small tract of open ground upon its 

 eastern side. 



The westerly motion, which varied from b to 40 mm., usually took 

 place between 18 or 21 hours and 6 or 9 hours, that is to say, the pendulum 

 commenced to move towards the west at about 6 or 9 a.m., and continued 

 this motion until 6 or 9 p.m. (fig. 7). During the night the easterly or i^eturn 

 motion was gentle, and usually less than the motion towards the west. 



On wet cloudy days no curves were visible. 



Tremors were not marked at this station. 



Comparing the jST.E. and S.W. motions of A with the E. and W. motions 

 at J in li4 instances these movements were completed at about the same 

 hour. In 21 instances, however, there is a difierence between them of 

 from 5 to 10 hours. 



An experiment which was made at this station was to dig a trench 

 round the hut on its south and west sides. This was 5 feet in depth, while 

 its distance from the column was about 10 feet. The only effect that this 

 produced upon the daily diagram seems to have been that the points of 

 inflection in the curve became somewhat sharper, the range of motion of 

 the pendulum remaining constant. 



Pendulum at K. — Sensibility, September 20, 1894, l°=4-5 mm., or 

 1 mm.=0"-50. November 21, 1894, 1° = ;3 mm. The installation of 

 this instrument, excepting the fact that it was exposed to open ground 

 towards the east and north, and sheltered by a grove of trees upon the 

 south and west, was similar to that at J. The instrument itself was like 

 that at J. 



The diurnal movements had a range of from 4 to 40 mm. The westerly 

 excursion usually commenced at 5 or 6 A.M., and continued until about 4 

 or 6 P.M. (fig. 8). The motion was therefore about one hour in advance of 

 that at J, which roughly corresponds to the difference in time at which 

 the ground in their respective vicinities were exposed to the morning sun. 

 Comparing the hours at which the easterly and westerly motions of J and 

 K were completed in fifteen cases, they closely agree. When these 

 hours do not agree, K has usually reached its western limit from one to 

 four hours before J. In two instances it completed this movement seven 

 hours after J, while in two other cases one pendulum has been near its 

 western limit, while the other has practically completed its movement in 

 an opposite direction. 



Tremors were not marked. The object in placing J and K, which 

 were 275 yards distant from each other, on opposite sides of a small grove 

 of trees, was with the expectation of finding that at the same time they 

 moved in opposite direction. It is seen that the expectation was not 

 realised. 



Fendulum at L. — This instrument, which in construction is very like 



