Q 151
The discrepancy between these two observations was to be expected as due to curvature and refraction. By taking the mean of the pair of observations the error due to curvature and refraction was eliminated and an approximate true difference in height obtained between Kowloon Bench Mark 64 and bollard.
Any error in this result of one pair of observations was further eliminated by taking ten pairs or twenty observations at various dates and the mean of the results accepted.
29. Levelling was also completed on the Fanling-Sha Tau Kok Road. This was commenced at the Fundamental Bench Mark at Fanling Railway Station and double levelling was carried to the Anglo-Chinese Boundary at Sha Tau Kok. All milestones were used as Bench Marks and valued and a Fundamental Bench Mark was fixed near milestone 32. The No. 3 Anglo-Chinese boundary stone was used as a Bench Mark, a brass rod 1" dia. and one foot in length being let into the stone.
In addition the Triangulation Station at Sha Tau Kok was valued and the bridge abutment over the river.
Double levelling was also carried out from Fanling Cross Roads (Milestone 6 on Fanling-Sha Tau Kok Road) to Sheung Shui and connected up to Milestone 34 on the main road. The closing error was well within the limit laid down as permissible. Levels were obtained of all road bridges and the railway bridge near Sheung Shui Station.
A Bench Mark (iron Staple) was fixed in the wall of Sheung Shui Police Station and valued.
30. Levelling in Hong Kong was somewhat interrupted owing to shortage of staff but the analysis of tidal readings from the Automatic Tide Gauges at Kennedy Town and Ah Kung Ngam has been carried on. The double levelling mentioned in the report for last year between "Rifleman's" bolt and the tide gauges was not entirely satisfactory and a new line of levels has been run between the bolt and Ah Kung Ngam (a distance of 5.6 miles). On this route there are 16 Bench Marks two of which are of the Fundamental type. One of these Fundamental Bench Marks was fixed in a solid rock foundation at North Point and the other at Ah Kung Ngam also in rock, within a few yards of the Tide Gauge. Double levelling has also been carried on between "Rifleman's" bolt and Western Market and existing Bench Marks valued. This will be shortly carried through to the Tide Gauge at Kennedy Town where a Fundamental Bench Mark has been fixed close to the gauge.
E. B. REED,
Supt. of Surveys.
HAROLD T. CREASY,
Director of Public Works.
HONG KONG, 14TH MAY, 1931,
Page 705
Page 706
Q 151
The discrepancy between these two observations was to be expected as due to curvature and refraction. By taking the mean of the pair of observations the error due to curvature and refraction was eliminated and an approximate true difference in height obtained between Kowloon Bench Mark 64 and bollard.
Any error in this result of one pair of observations was further eliminated by taking ten pairs or twenty observations at various dates and the mean of the results accepted.
29. Levelling was also completed on the Fanling-Sha Tau Kok Road. This was commenced at the Fundamental Bench Mark at Fanling Railway Station and double levelling was carried to the Anglo-Chinese Boundary at Sha Tau Kok. All milestones were used as Bench Marks and valued and a Fundamental Bench Mark was fixed near milestone 32. The No. 3 Anglo-Chinese boundary stone was used as a Bench Mark, a brass rod 1" dia. and one foot in length being let into the stone.
In addition the Triangulation Station at Sha Tau Kok was valued and the bridge abutment over the river.
Double levelling was also carried out from Fanling Cross Roads (Milestone 6 on Fanling-Sha Tau Kok Road) to Sheung Shui and connected up to Milestone 34 on the main road. The closing error was well within the limit laid down as permissible Levels were obtained of all road bridges and the railway bridge near Sheung Shui Station.
}
A Bench Mark (iron Staple) was fixed in the wall of Sheung Shui Police Station and valued.
30. Levelling in Hong Kong was somewhat interrupted owing to shortage of staff but the analysis of tidal readings from the Automatic Tide Gauges at Kennedy Town and Ah Kung Ngam has been carried on. The double levelling mentioned in the report for last year between "Rifleman's" bolt and the tide gauges was not entirely satisfactory and a new line of levels has been run between the bolt and Ah Kung Ngam (a distance of 5.6 miles). On this route there are 16 Bench Marks two of which are of the Fundamental type. One of these Fundamental Bench Marks was fixed in a solid rock foundation at North Point and the other at Ah Kung Ngam also in rock, within a few yards of the Tide Gauge. Double levelling has also been carried on between "Rifleman's" bolt and Western Market and existing Bench Marks valued. This will be shortly carried through to the Tide Gauge at Kennedy Town where a Fundamental Bench Mark has been fixed close to the gauge.
E. B. REEI),
Supt. of Surveys.
HAROLD T. CREASY,
Director of Public Works.
HONG KONG, 14TH MAY, 1931,
Page 705Page 706
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