New York Weather Bureau. 381 



through the center of which the lower end of the wind-vane axis 

 passes. This ring is divided into four segments or quadrants, 

 each being connected with a wire passing to the corresponding 

 quadrant of a similar ring (b) on the register in the distant build 

 ing. A metallic contact piece secured to the wind-vane axis 

 bears against the quadrants of (a), passing from one to the other 

 fas the direction of the wind changes. The ring (b) also has its 

 contact piece, which is secured to the axis of the recording cylin- 

 der, said cylinder being rotated uniformly by clock work at the 

 rate of one turn in 6 minutes. Its contact piece is in circuit with 

 one pole of an electric battery, the other pole being grounded; and 

 the contact piece of (a) is also grounded through the wind-vane 

 axis. Hence, when the contact piece of (b), in its steady rotation, 

 passes over the quadrant corresponding to that upon which the 

 wind-vane contact is resting, a current is allowed to pass through 

 (b) and its coninecting wire to (a) and thence to the ground. This 

 current actuates ai^ electro-magnet in the register, thus pressing 

 a pen against the cylinder until its contact piece, by rotation, 

 passes off from the quadrant corresponding to the wind direction, 

 when it is released. The pen falls vertically the length of the 

 cylinder once in 24 hours, and, in the manner explained above, 

 at every revolution of the cylinder, leaves a trace upon that part 

 of its circumference which corresponds to the direction of the wind 

 at the time. 



The register, as thus described, records the wind direction only 

 to four points; but by broadening the contact piece of (a) so that 

 it can bear upon portions of two quadrants at the same time, as, 

 for example, upon the north and west quadrants, for a northwest 

 wind, both north and west are recorded upon the cylinder, and 

 such a tracing is read northwest. 



As previously stated, the wires: of the velocity register pass 

 through the hollow axis of the vane; and at the lower extremity 

 of the latter are connected through mercury cups with wires run- 

 ning to the Engineering building. At every hundredth revolution 

 of the anemometer, corresponding to 100 meters of wind, a circuit 

 is made through an electro-magnet of the register; and this turns 

 the proper recording cylinder through one one-thousandth part of 



