SOME REMARKS ON 
207 
any point of the curve drawn through the extremities of the 
equidistant ordinates will measure the velocity at the corres- 
ponding time. 
Of all self-recording instruments for measuring the velocity 
of wind, that of Mr. Beckley is the most successful and most 
generally used. The original form was described by him iiT 
1S6S, but in its present form, at Kew, it has been somewhat 
modified and improved. Both direction and velocity are recorded 
by curves on separate strips of paper. The latter quantity 
is shewn at a glance by the inclination of the curve, but in 
practice is read by the ' distance moved by the tracing point or 
its equivalent in regular intervals of time. The embossing 
anemometer of Messrs. Beckley and Casella records on one strip 
of paper both the number of miles of wind passing the cups 
(measured by their revolutions) and its direction. This is 
attained by causing the strip to be drawn over embossed rollers 
by the action of the cup- vane spindle on suitable mechanism, and 
at regular intervals of time stamping an arrow by the side of 
the embossed figures, the direction of the arrow shewing the 
direction of the wind at that instant. There are numerous 
devices for obtaining a record of the revolutions of the cups, but, 
of course, to shew the velocity of the wind at every instant 
in this way the element of time must be introduced, which has 
been shewn to have been very satisfactorily done in Mr. Beckley’s 
anemometer. 
It occurred to the author that an instrument might be 
constructed which should directly shew the velocity at every 
instant by employing the principle of the pendulum governor in 
conjunction with Robinson’s cups. If the sleeve moved by the 
rising and falling of the weights carried a pencil, a continuous 
record of velocity might be obtained on a drum moved by clock- 
^ British Association Report, 1858, Vol. 28. 
K 
