SOME GEO-PHYSICAL OBSERVATIONS AT BURRINJUCK. 459 



deflection prior to the 22nd February is not known. In the 

 case of the meridian boom an increase in the ordinate 

 represents a deflection of the boom towards the east. In 

 the case of the east and west boom a decrease in the 

 ordinate corresponds to a deflection of the boom to the 

 north. The curve representing the water level is drawn 

 to a scale on which one centimetre represents twenty feet 

 of water. The actual water level on 22nd February was 

 fifty-two feet above the river bed at the site of this 

 pendulum. 



The abscissae represent the times corresponding to the 

 ordinates of the curves and are drawn to a scale of twenty 

 days to one centimetre. 



Figure 2. — Pendulum No. 2 (Strassburg Pendulum). 



The deflections of the vertical registered by both booms 

 are represented by the changes in the ordinates of the 

 curves. These are drawn to a scale on which one centi- 

 metre represents about 0*64 seconds of arc. The amount 

 of the deflection prior to 22nd February 1915 is not known. 

 In the case of the meridian boom an increase in the ordinate 

 represents a deflection of the boom towards the east. In 

 the case of the east and west boom a decrease in the 

 ordinate represents a deflection towards the south. The 

 curve representing the water level is drawn to a scale on 

 which one centimetre measures twenty feet of water. An 

 increase in the ordinate corresponds to a rise of the water 

 level. The actual water level at the 22nd of February, 

 1915, was eighty feet above the river bed at the site of 

 this pendulum. The abscissae of all the curves represent 

 the times corresponding to the ordinates, and are drawn 

 to a scale of twenty days to one centimetre. 



