380 Eighth Annual Kei'ort of the 



to the instrument transmit tlie current to a Gibbon reg- 

 ister located on the first floor of the building. A screw- 

 thread is cut upon the axis of the recording cylinder 

 of this register, and as it is rotated hj clockwork at the rate of 

 one turn in 6 hours^ the screw also gives it a motion lengthwise 

 with the axis, so that a pen in a fixed position would trace a spiral 

 line around its surface. In fact, the recording pen is attached to 

 the pole piece of an electro-magnet in circuit with the anemometer, 

 and hence, at every mile-contact, a notch is made in the spiral line 

 traced by the pen upon the recording sheet, and the number of 

 miles of wind travel for any given time is found by counting the 

 number of these notches. It is necessary to replace the recording 

 sheet each day. 



A second wind vane and pair of anemometers are mounted on 

 the tower of McGraw hall, one of the University buildings, stand- 

 ing on the crest of the hill and overlooking the Cayuga valley. 

 These instruments are 12 feet above the roof of the tower, and 140 

 feet from the ground, being thus more exposed to the full force 

 of the wind than those just described. The anemometer for meas- 

 uring horizontal wind currents is of the Richard'® coinstruction, 

 consisting of a small wind-mill with G inclined vanes radiating 

 from a horizontal axis, which axis, extending into a metal case, 

 makes an electric contact with each hundred revolutions by means 

 of suitable gearing. The entire apparatus revolves freely about 

 a vertical axis in the same manner as an ordinary wind-mill, and 

 is made to face the wind by a broad, wedge-shaped tail at the 

 rear. The vertical axis, whicli is tubular, passes down into the 

 interior of the tower, and within it are carried the wires which 

 transmit the measurements of wind velocity. 



As the instrument was furnisiied by the makers, the cylinder 

 upom which the record of wind direction is traced, was fixed to 

 the lower end of the axis of the wind-vane; but since the 

 registers at the central station are located in the Engineer- 

 ing building, 000 feet distant from the anemometers, a dif- 

 ferent arrangement was necessary. The present device con- 

 sists, firstly, of a fixed metallic ring (a) 3 inches in diameter, 



