648955-1892-Report-on-Annual-Rainfall — Page 1

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THE HONGKONG GOVERNMENT GAZETTE, 16TH JANUARY, 1892.

GOVERNMENT NOTIFICATION.-No. 24.

The following report on the recurrence of droughts and annual rainfall in Hongkong is published for general information.

By Command,

Colonial Secretary's Office, Hongkong, 16th January, 1892.

W. M. GOODMAN, Acting Colonial Secretary.

H.K.O. No. 80.

HONGKONG Observatory,

7th September, 1891.

SIR,-In accordance with instructions given in your letter No. 1355 of the 31st July ultimo, I have the honour to enclose a table of rainfall in Hongkong during this and thirteen previous years.

2. In my letter of the 5th ultimo, (H.K.O. No. 72) I have explained why I cannot go back any farther, and I now beg to offer some further explanations for the information of the Surveyor General and the Superintendent of the Civil Hospital, the latter having sent me a return of fever cases to be compared with the meteorological registers.

3. Droughts may be expected when the mean atmospheric pressure is above the average, and when the average velocity of the wind is below the average. The mean temperature is not affected by the amount of rain, but the mean elastic force of water-vapour and the average cloudiness increase and decrease with the rain.

4. After the end of April there need be no fear of drought. There is always heavy rain up to the end of August. But then the rainfall decreases quickly as a rule and as it is moreover extremely variable during September and October, these months should be watched. When rainfall is defective in both months a drought may occur during the following six months, though it is sometimes prevented by heavy winter rains.

5. The drought of 1890-1891 was without precedent within fourteen years, but that does not make it likely that such a drought may not occur again within fourteen years.

Rain is a very variable and uncertain element and no forecast for any season can be made in advance.

When the rain-

6. Malarial fevers, as stated in my annual report for 1885, follow heavy rainfall. fall has been excessive during a certain month, there is an increase of malarial fever during the following month, and as this appears to be particularly severe among those who dwell near the nullahs, it is very likely caused by the decay of animal or vegetable inatter carried down by the torrents from higher ground and deposited at a lower level, by disturbance of ground saturated with malaria, by the growth of bacteria in wet soil, and by the rise of the level of sub-soil water.

7. Cases of malarial fever among the Police Force of Hongkong (average number about 700) during each month of the three years 1888 to 1890 inclusive were compared with the rainfall during the previous month with the following result :-

Cases.

5

Rain. 2.9 inch.

10

3.1

Rain. 0- 1 inch. 1 2

Cases.

11

15

">

15

8.9

3- 7

· 19:

27

20

6.7

and

8-12

22

25

9.1

13-17

35

30

18.1

18-22

21

7

35

8.4 40 11:0

23-27

25

""

8. The apparent disagreement between these two tables shows that three years do not suffice for drawing quantitive conclusions, but at the same time the connection referred to above appears at a glance.

9. Further information about the annual distribution of rainfall and its consequences will not be available till several more years of observations and research have passed by.

I have the honour to be,

Sir,

Your most obedient Servant,

W. DOBERCK, Director.

The Honourable W. M. GOODMAN,

Acting Colonial Secretary,

etc.

etc.,

etc.,