EARTH PULSATIONS. 327 



character of these records is such that we might imagine 

 the soil on which the support of the pendulum had rested 

 to have been slowly tilted, and slowly lowered. They are 

 the most marked on those pendulums provided "with an 

 index writing a record of its motions on a smoked glass 

 plate, which index is so arranged that it gives a multi- 

 plied representation of the relative motion between it and 

 the earth. As motions of this sort might be possibly due 

 to the action of moisture in the soil tilting the support 

 of the pendulum, and to a variety of other accidental 

 causes, we cannot insist on them as being certain indica- 

 tions that there are slow tips in the soil, but for the 

 present allow them to remain as possible proof of such 

 phenomena. 



Evidence of displacement of the vertical, which are 

 more definite than the above, are those made by Bertelli, 

 Eossi, Count Malvasi, and other Italian observers, who, 

 whilst recording earth tremors, have spent so much time 

 in watching the vibrations of stiles of delicate pendulums 

 by means of microscopes. As a result of these observa- 

 tions we are told that the point about which the stile of 

 a pendulum oscillates is variable. These displacements 

 take place in various azimuths, and they appear to be 

 connected with changes of the barometer. I have made 

 similar observations in Japan. 



From this, and from the fact that it is found that a 

 number of different pendulums differently situated on 

 the same area give similar evidence of these movements, 

 it would hardly seem that these phenomena could be 

 attributed to causes like changes in temperature and 

 moisture. M. S. di Rossi lays stress on this point, especially 

 in connection with his microseismograph, where there are 

 a number of pendulums of unequal length which give 

 indications of a like character. The direction in which 



