1909-10.] 
391 
Proposal for an Anemometer. 
Fig. 4 shows the arrangement by which the sphere is driven and its 
axis caused to veer so as to be always parallel to the wind. The vertical 
rectangular framework R R is continuous with the hollow axis S of the 
vane, and therefore turns with it ; and its plane is the plane of the vane. 
T is the lower end of the axis of the toothed wheel that is driven by the 
wind- wheel. Its connection with the sphere is by a flexible part and spur- 
wheel gearing capable of giving either of two speeds to the sphere. The 
axis of the sphere must be capable of accurate adjustment so that it shall 
be truly level, and so that the centre of the sphere is exactly in the prolonga- 
tion of the vertical axis of the wind-vane. 
Section 2. — The second part of the instrument is that by which the 
horizontal discs in the course of their rotation actuate the pens that make 
the final record on the uniformly turning recording cylinders. 
Each disc is mounted on a thin vertical axis, which is rather more than 
supported at its lower end by a spring, the excess of the pressure of the 
spring over the weight of the disc and axis being used to keep the bevelled 
edge of the disc in gentle contact with the rotating sphere. The axis of the 
disc has on it a “ lantern ” or toothed- wheel gearing which drives a train of 
clockwork such as that of a cheap clock. The final or most slowly moving 
axis of the clockwork causes the pen to move over the recording cylinder. 
Continuous winds from one direction will, of course, carry the pens to 
the ends of the cylinders. By a simple device, however, it is easy to contrive 
that they shall, when this happens, be released so as to return to zero, and 
there be once more caught by the moving clockwork. 
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