[PLUVIOMETER FOR SYDNEY OBSERVATORY. 115 
at the rate of 1 inch per hour; but the clock is provided with an 
additional wheel which can be thrown into gear in a moment, an 
which — causes the cylinder to revolve at the rate of 2 inches 
per hou s is only used for heavy storms. 
The bop and bottom bearing of the cylinder project beyond it 
1} in. and form the guides for the pencil carriage just described, 
record is made by a glass pen. This frame and pen serve to pull 
It will be seen from what has already been said that the motion 
of direction pencils ak velocity pen are in straight lines; and it is 
only necessary to add that the — record in line so that both 
point to the same hour line at once. The direction pencil accords 
on the upper part of the paper fie 4 inches and the velocity pen 
records on the lower 4 inches, and the spare pencils do not catch 
n the pen because, when passing it, they are riding on the guide 
which lifts them off the paper except when over that part on 
which they have to record. 
it is caught in a small glass funnel fitting the tube, and thence led 
into the tip bucket which happens to be uppermost. These buckets 
har page 0:20 in. of rain, and are fixed bottom to bottom on an 
such a way that when standing upright they are not 
Talicastl ver tend to fall over. This tendency is _ prevented by a 
catch which holds them upright until 0-20 in. rain has fallen in. 
As the rain accumulates, the bucket which is at the end of a lever 
and held up by a spiral spring, descends, on down with it the 
pen frame which records the rain, and is similar to the other two. 
By the time the bucket has received the 0: 20 j in. it has descended 
ae: 
momentum carries it 180°, or until the oflier bucket has taken its 
ogee to receive the r ain and follow the same motions. When 
