404 Mr. Mallet's Notice of the British Earthquahe of November 9, 1852. 



nearly so, from the north towards the south could produce no effect but that of 

 presshig it closer to the wall ; or, if from south to north, of causing it to swing 

 outwards from the wall, like a pendulum, suspended from the rings. No motion 

 (within the limits here in question) from east to west, horizontally, that is, in 

 the plane of the wall, could affect it at all. The vertical element of motion is 

 indispensable to account for its having fallen. 



If this vertical motion had been one emerging upwards from north to south, 

 unless the angle were almost perfectly vertical, its effect would be merely to 

 increase a little the strain upon the points of support for the moment, and to 

 cause the lower part of the picture to swing out from the wall. But if the 

 direction of motion were diagonally upwards from south to north, the whole 

 force due to the vertical component, less the friction of the picture against the 

 wall, would be expended in straining the points of support, and that due to 

 the horizontal component in throwing the picture bodily off from the face of 

 the wall. The picture was actually found thrown forward about eighteen 

 inches from the wall at the point where it was arrested in its descent, after a 

 fall of about four feet. I conclude, therefore, that the actual direction of 

 emergence of the wave in the city of Dublin was from south to north (with 

 probably a few degrees westerly bearing), and upwards at an angle of from 25 

 to 30 degrees with the horizon. The following diagram may make this more 

 intelligible. ; • , 



Fig. 1. 



Fig. 2. 



Fig. 3. 



Fig. 1. PJau of passage. 



Fig. 2. Vertical section through BC, looking southwards. 

 Fig. 3. Vertical section through DE, looking westwards. 



The dotted lines show the original position of the picture ; the hard lines its position when 

 founddislodged and wedged between the side-walls. 



