F 2
The small factors in November and December indicate that either the velocities recorded by the Beckley instrument are too great, or by the Dines instrument too small. The mean velocities for October, November, and December, as recorded by the Beckley Anemograph, were respectively 0.4, 0.6, and 0.5 m.p.h. below normal. This does not suggest that the instrument was recording relatively greater velocities in November and December than in October. Moreover, it is unlikely, for mechanical reasons, that after a great number of years the instrument should suddenly commence to record too great velocities. The other alternative is that the Dines instrument is recording too small velocities, but of this the condition of the instrument gives no indication. Had the change occurred in August it might have been attributed to the change in the pipes on July 31, but it will be seen that the mean factor for May to July was practically the same as for August to October.
Thermometers. All thermometers in use were compared with the Kew Standard in winter and summer.
Thermograph.—The Richard dry and wet bulb thermograph, ordered to replace the old Kew photographic thermograph, was received on March 20, and set up in the thatched shelter the following day. The recording cylinder is 5 inches in diameter, and turns once in 24 hours. The electrical time-break apparatus was completed on April 22. The pens are lifted from the paper, for the first three minutes of each hour, by a make-contact on one of the electric dials. The thermometers are aspirated from the 59th to the 60th minute of each hour by a fan, operated by a similar contact on another dial, air being drawn into the shelter through a 14-inch zinc pipe. Comparison between the eye observations of thermometers rotated in the open air and the records of the Richard thermograph indicate that the relation between the temperature in the shelter and in the open air is not constant. The precise nature of the variation has not yet been investigated.
Interesting records of the effect of the electric fan on the wet bulb thermometer are being classified under varying conditions of temperature, humidity, and wind.
III. METEOROLOGICAL OBSERVATIONS AT THE OBSERVATORY.
Continuous photographic records showing the variations of barometric pressure were obtained with the Kew barograph, and automatic records of the direction and velocity of the wind with a Beckley and a Dines-Baxendell anemograph, modified as described in the Report for 1912. The amount of rain is recorded automatically by a Beckley and a Nakamura pluviograph, the amount of sunshine by a Campbell-Stokes universal sunshine recorder, and the relative humidity of the air by a small Richard hair hygrograph. Since March 21 automatic records of the temperature of the air and of evaporation have also been obtained with a Richard dry and wet bulb thermograph.
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F 2
The small factors in November and December indicate that either the velocities recorded by the Beckley instrument are too great, or by the Dines instrument too small. The mean velocities for October, November, and December, as recorded by the Beckley Anemograph, were respectively 04, 06, and 0-5 m.p.h. below normal. This does not suggest that the instrument was recording relatively greater velocities in November and December than in October. Moreover, it is unlikely, for mechanical reasons. that after a great number of years the instrument should suddenly commence to record too great velocities. The other alternative is that the Dines instrument is recording too small velocities, but of this the condition of the instrument gives no indication. Had the change occurred in August it might have been attributed to the change in the pipes on July 31, but it will be seen that the mean factor for May to July was practically the same as for August to October.
Thermometers. All thermometers in use were compared with the Kew Standard in winter and summer.
Thermograph.—The Richard dry and wet bulb thermograph, ordered to replace the old Kew photographic thermograph, was received on March 20, and set up in the thatched shelter the fol- lowing day. The recording cylinder is 5 inches in diameter, and turns once in 24 hours. The electrical time-break apparatus was completed on April 22. The pens are lifted from the paper, for the first three minutes of each hour, by a make-contact on one of the electric dials. The thermometers are aspirated from the 59th to the 60th minute of each hour by a fan, operated by a similar contact on another dial, air being drawn into the shelter through a 14-inch zinc pipe. Comparison between the eye observations of thermome- ters rotated in the open air and the records of the Richard thermo- graph indicate that the relation between the temperature in the shelter and in the open air is not constant. The precise nature of the variation has not yet been investigated.
Interesting records of the effect of the electric fan on the wet bulb thermometer are being classified under varying conditions of temperature, humidity, and wind,
III. METEOROLOGICAL OBSERVATIONS AT THE OBSERVATORY.
Continuous photographic records showing the variations of barometric pressure were obtained with the Kew barograph, and automatic records of the direction and velocity of the wind with a Beckley and a Dines-Baxendell anemograph, modified as described in the Report for 1912. The amount of rain is recorded automa- tically by a Beckley and a Nakamura pluviograph, the amount of sunshine by a Campbell-Stokes universal sunshine recorder, and the relative humidity of the air by a small Richard hair hygro- graph. Since March 21 automatic records of the temperature of the air and of evaporation have also been obtained with a Richard dry and wet bully thermograph.
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