14. During the past year several hundred indirect comparisons of barometers and aneroids on board ship have been made. A few barometers, aneroids, thermometers and one portable anemometer have been compared for various people at the Observatory.
15. The rainfall in inches registered by the gauge placed in the Police compound at Taipo, New Territories, was as follows:- January 1.09, February 0.57, March 0.70, April 3.84, May 0.46, June 29.31, July 11.67, August 14.12, September 15.58, October 0.03, November 2.83, December 0.92, the total for the year being 81.12 inches. On an average of the five years during which this gauge has been in operation the rainfall measured at Taipo exceeds that recorded at the Observatory by 20 per cent. The rainfall recorded in 1910 at the Public Gardens in Hongkong, was as follows:- January 0.90, February 0.50, March 1.04, April 3.97, May 0.96, June 19.16, July 18.36, August 11.83, September 17.28, October 0.31, November 2.66, December 0.82, the total for the year being 77.79 inches, as against 70.12 inches registered at the Observatory. The excess of the record at the former station over that of the latter has, on an average of the past five years, been 10 per cent.
16. On the completion of the necessary alterations to the roof of the Observatory by the Public Works Department, the Dines-Baxendell pressure-tube Anemograph, which was received from London early in the year, was mounted in April, the recording apparatus being placed in the hall.
From a comparison made during the period May to December inclusive, between the records of this instrument and those of the standard pattern Robinson Anemograph in use here, the factor with which the actual run of the cups of the latter should be multiplied in order to obtain the true velocity—on the assumption that this is given by the pressure-tube instrument—was found to be 2.22. This mean factor gives the result as determined from all the observations, irrespective of velocity and direction, and it agrees with that (2.2) found and adopted for instruments of exactly similar dimensions by the Meteorological Office in London, as against Dr. Robinson's original factor 3.0, formerly in use.
It appears, however, that the factor is not quite constant at the lower velocities, apart from the value found for light airs (velocity by Robinson Anemograph miles 0 to 5) where the factor is much smaller than elsewhere, due apparently to the fact that the momentum readily acquired by the cups in very light and fitful airs, causes them to revolve for some time after the impulse that set them in motion has ceased, and also to the chance that the head of the pressure-tube instrument may not always be properly aligned to the wind direction. Between 16 and 30 miles the factor is practically constant. At higher velocities enough observations are not yet available, and the same remark applies to variation of the factor with wind direction. So far it is found that the value is greater for winds from the Easterly quadrant than from all other directions, and it is worthy of note that the velocity is much steadier in character from this quadrant, than from elsewhere. Later it may be found advisable to raise the head of the pressure-tube instrument a few feet,
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14. During the past year several hundred indirect comparisons of barometers and aneroids on board ship have been made. A few barometers, aneroids, thermometers and one portable anemometer have been compared for various people at the Observatory.
15. The rainfall in inches registered by the gauge placed in the Police compound at Taipo, New Territories, was as follows:- January 1.09, February 0.57, March 0.70, April 3.84, May 0.46, June 29.31, July 11.67, August 14.12, September 15.58, October 0.03, November 2.83, December 0.92, the total for the year being 81.12 inches. On an average of the five years during which this gauge has been in operation the rainfall measured at Taipo ex- ceeds that recorded at the Observatory by 20 per cent. The rain- fall recorded in 1910 at the Public Gardens in Hongkong, was as follows:-January 0.90, February 0.50, March 1.04, April 3.97, May 0.96, June 19.16, July 18.36, August 11.83, September 17.28, October 0.31, November 2.66, December 0.82, the total for the year being 77.79 inches, as against 70.12 inches registered at the Observatory. The excess of the record at the former station over that of the latter has, on an average of the past five years, been 10 per cent.
16. On the completion of the necessary alterations to the roof of the Observatory by the Public Works Department, the Dines-Baxen- dell pressure-tube Anemograph, which was received from London early in the year, was mounted in April, the recording apparatus being placed in the hall.
From a comparison made during the period May to December inclusive, between the records of this instrument and those of the standard pattern Robinson Anemograph in use here, the factor with which the actual run of the cups of the latter should be multiplied in order to obtain the true velocity-on the assumption that this is given by the pressure-tube instrument--was found to be 2.22. This mean factor gives the result as determined from all the observations, irrespective of velocity and direction, and it agrees with that (2.2) found and adopted for instruments of exactly similar dimensions by the Meteorological Office in London, as against Dr. Robinson's original factor 3.0, formerly in use.
It appears, however, that the factor is not quite constant at the lower velocities, apart from the value found for light airs (velocity by Robinson Anemograph miles 0 to 5) where the factor is much smaller than elsewhere, due apparently to the fact that the momentum readily acquired by the cups in very light and fitful airs, causes them to revolve for some time after the impulse that set them in motion has ceased, and also to the chance that the head of the pres- sure-tube instrument may not always be properly aligned to the wind direction. Between 16 and 30 miles the factor is practically constant. At higher velocities enough observations are not yet available, and the same remark applies to variation of the factor with wind direction. So far it is found that the value is greater for winds from the Easterly quadrant than from all other directions, and it is worthy of note that the velocity is much steadier in character from this quadrant, than from elsewhere. Later it may be found advis- able to raise the head of the pressure-tube instrument a few feet,
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