Sessional_Paper_1890 — Page 269

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22. At the Observatory the cisterns of the barograph and standard barometer are placed 109 feet above mean sea level. The bulbs of the thermometers are rotated 108 feet above mean sea level and 4 feet above the grass.

The solar radiation thermometer is placed at the same height. The run of the rain-gauge is 105 feet above mean sea level and 21 inches above the ground. At Victoria l'eak the instruments, except the solar radiation thermometer and the rain-gauge are placed in the lookout. The cistern of the barometer is 1814 feet above sea level. The bulbs of the thermometers are 4 feet above the floor except the maximum thermometer, which is a few inches higher. The rim of the rain-gauge is 8 inches in diameter and one foot above the ground.

23. The monthly Weather Reports are arranged as follows:-

Table I. exhibits the hourly readings of the barometer reduced to freezing point of water but not to sea level, as measured (at two minutes to the hour named) from the barograms.

Tables II and III. exhibit the hourly readings of the temperature of the air, and of the temperature of evaporation as determined from readings of thermometers exposed in a suitable shelter, and as measured from the thermograms. All readings are reduced to the rotating thermometers by comparisons made every three hours. Table II exhibits also the extreme temperatures during the day reduced to the rotating thermometer by aid of comparisons made during the hottest and coldest part of the day. Table III. exbibits also the solar radiation (black bulb in vacuo) maximum temperature reduced to the Kew arbitrary standard.

Table IV. exhibits the mean relative humidity in percentage of saturation and mean tension of water vapour present in the air expressed in inches of mercury for every hour in the day and for every day in the month calculated by aid of Blanford's tables from the data in Tables II and III.

Table V. exhibits the duration of sunshine expressed in hours from half an hour before to half an 'hour after the hour (true time) named.

Table VI. exhibits the amount of rain in inches registered from half an hour before to half an hour after the hour named. It exhibits also the duration of rain estimated at the Observatory. The rain- fall at Victoria Peak is measured at 10a. and entered to preceding day, but it is evident that the observer does not attend to the gauge every day.

Table VII. exhibits the velocity of the wind in miles and its direction in points (0-31). The velocity of the wind is measured from half an hour before to balf an hour after the hour named; but the direction is read off at the hour except when it is very light and changeable, in which case the average direction during the hour is estimated, taking into account the velocity from different quarters. The direction is not noted when the velocity is below 1.5 miles an hour. The vane is to be depended on except when the velocity is uniform (which of course rarely happens) and below 3 miles an hour.

Table VIII. exhibits for every hour in the day the mean velocity of the wind reduced to 4 as well as to 2 directions, according to strictly accurate formulæ, and also the mean direction of the wind. The method made use of during the past five years has been abandoned as it does not furnish the mean direction for every day, which latter is this year given in Table VII.

Table IX. exhibits the readings of the barometer reduced to freezing point of water but not to sea level, and of the thermometers, and the observations of the direction (to two points) and force (0-12) of the wind at Victoria Peak.

Table X. exhibits the amount (0–10), name and direction whence coming of the clouds. Where the names of upper and lower clouds are given but only one direction, this refers to the lower clouds.

24. The following annual weather report for 1889 is arranged as follows:-

Table IV. exhibits the mean values for the year (or hourly excess above this) obtained from the means given in the monthly reports. The mean hourly intensity of rain is obtained from Table VI. of the monthly reports in connection with Table V of this report. The total amount of rain was 119.715 at the Observatory and 133.32 at the Peak. The total duration registered at the Observatory was 905 hours. There fell at least 0.01 inch of rain on 161 days at the Observatory. The figure 103 given for the Peak is evidently inaccurate.

Table V. exhibits the number of hours during a portion of which at least 0.005 inch of rain was registered.

Table VI. exhibits the total distance traversed by as well as the direction and average velocity of winds from bi-quadrantal points, obtained from the tables published on the first page of each monthly report.

Table VII. exhibits the number of days on which certain meteorological phenomena were regis tered and also the total number of thunderstorms noted in the neighbourhood during the past year.

Table VIII. shows the frequency of clouds of the different classes.

Table IX. is arranged the same as last year.