68
Then began the most appalling thunderstorm within my own experience, or that, I venture to believe, of the majority of the residents in the Colony. For hours flash succeeded flash in rapid succession, and the roll of the thunder was almost uninterrupted, while the rain descended in masses. Several buildings were struck by lightning, and six coolies were killed in a matshed at the Peak. The dam- age to the structure, in the case of the buildings which I have had an opportunity of inspecting, was singularly slight. The storm raged with greatest intensity between the hours of 1 and 5 A.M. of the 30th. The rain that fell during that morning is so exceptional that I give below the result detail.
hundredths.
inches.
Hour ending 12.30 A.M.,
0
84
1.30
1
80
3)
>>
2.30
2
30
3.30
3
20
4 hours 11.90
>>
4.30
3
40
3 hours 9.60
5.30
3
00
11
6.30
1
62
11
11
Total in 7 hours,.......
16
16
5. After 6 A.M. the storin abated, but rain continued to fall until about 5 P.M., when it ceased. The total rain which fell during the storm from 3 A.M. of the 29th to 5 P.M. of the 30th, a period of 38 hours, was 33.11 inches, and of this quantity the very remarkable fall of 27.44 inches occurred in the 24 hours ending 6.30 AM. of the 30th (nearly twenty seven and a half inches).
6. Before proceeding further it may be interesting to add that the total rainfall recorded for May was 48.84 inches, and for the six months ended 30th of June 75.45 inches. Comparing this with the records of the five years ending 1888, I find that the annual average is 84.84 inches, of which an average of 35.6 inches fell in the first half of the year, while the maximum monthly fall during these five years was 31.36 inches (in June 1885). It therefore follows that the rainfall of the past half year very nearly equals the average annual rainfall, and is more than double the quantity that fell in the corresponding period in former years, while the quantity that fell in May was one-third greater than that of any previous month, during these five years.
7. I have dwelt somewhat at length on this remarkable down-pour because, so far as I am able to ascertain from the limited records accessible to me here, the aggregate rainfall during this storm is without precedent in the case of any storm of equal duration, and it is specially noteworthy that the fall during certain hours, and the maximum for 24 hours, appear (if I may be permitted the expression) to break the record. My authorities are two standard works on Hydraulics, but the data are necessarily imperfect as they do not extend to a later date than 1875. I would call attention however to this very interesting and important subject of enquiry, in the hope that my imperfect comparison may be supplemented (and corrected if necessary) by those who may have leisure for investigation, and access to more recent records.
The practical importance of the subject is manifest, since we must depend on the accuracy of the meteorological returns for guidance in designing works of drainage and water supply.
8. I should add that the observations were made at the Observatory at Kowloon, two miles north of the centre of the Victoria rainfall area. It is I think probable that the results may be safely assumed as indicating approximately the rainfall on the main island, but it would be well to bear in mind that the proximity of the steep mountain slopes to the City, render it possible, judging by the records of analogous sites, that the rainfall in the City and on the mountain slopes above, was greater, rather than less, than the rainfall at Kowloon.
countries.
that
9. For the purpose of comparison I will now quote some exceptional rainfalls recorded in other At Nottingham on 13th of August, 1857, 5 inches fell in about 5 hours. During my residence in Cyprus (December, 1880) a flood, disastrous to life and property, occurred at Limassol, where a fall of 5 inches was registered (nearly the whole falling in 4 hours). It is noteworthy that at Kowloon more than double this quantity fell in the same space of time. I can find no record elsewhere of a maximum hourly fall equal to that at Kowloon, viz., 3.4 inches, although it appears the maximum on 30th May was slightly exceeded by an observation made at the Kowloon Observatory in July, 1886, when 3.48 inches was registered in one hour. Those who carefully observed the storm will, I think, agree with me, that when at its height, the down-pour was not constant for any consi derable consecutive period, but that for short periods it was exceptionally severe, so that if the fall could have been measured for a limited period of say a quarter, or half an hour, I have little doubt that the result would have been at the rate of fully four inches per hour. In designing works in which it is necessary to provide for a maximum fall, it would in my opinion be unsafe, in the light of recent experience, to calculate on a smaller fall than four inches per hour.
10. I would here remark that it may be argued that I am assuming that all the water that falls from the clouds is at once discharged into the water courses, and that I am allowing nothing for absorption. To this I submit that in the case of a heavy rainfall, occurring on such steep slopes as those which form the back-ground of the City, at a time when the soil has been saturated by previous heavy rains, a careful observer will, I think, be convinced that, practically speaking, all the water that falls is discharged forthwith into the sea.
11. To return to the records of rainfall in other places, the greatest fall in 24 hours I can find registered is 20.58 inches at Madras on 21st of October, 1846. The maximum at Kowloon was 27.44 inches, or about one third greater.*
12. I may conclude my observations on rainfall by adding, that although the records of Hong- kong appear to be exceptional, as regards the rain which fell in a single hour, and during periods of four hours, and of 24 hours, the recorded monthly and annual rainfall of this Colony sink into insignificance compared with those of some other parts of the world. If we take the returns for Hong- kong of the past six years we find that the maximum monthly rainfall is 484 inches, and the maximum annual fall is 109 inches, while at Cherrapungi in Assam, at 4460 feet above sea level, 243 inches have been guaged in a single month (June, 1860) and during the same year 615 inches of rain fell. The monthly and annual rainfall at Cherrapungi is therefore more than five times greater than Hongkong.
13. I have been unconsciously led into considerable length on the question of rainfall, owing to the interesting nature of the enquiry, and the phenomenal character of the late storm. not without a practical application, for as the storin was exceptional in its nature, so also was the The subject is injury that resulted to public and private property; and it is noteworthy that the periods when the greatest damage occurred coincided precisely with the hours of maximum rainfall, i.e. from 10 A.M. to Noon of the 29th and from 3 to 6 A.M. of the 30th. No doubt exaggerated estimates were made at the time of the loss incurred, but this was not surprising; as the ruin wrought by the uncontrollable power of this rush of water was evident on every side, and was on a scale, and of a nature, to impress the imagination. I now propose to describe generally the effects of the storm and (as furnishing fuller details on some points) I forward herewith reports by Mr. COOPER (Appendices C and D) dated 23rd and 26th June où the damage sustained by the Tytam Water-works, and by roads outside the limits of the City, and a report by Lieut.-Colonel CHAMPERNOWNE, R.E. on the streets of the City. (Appendix E).
14. I have already referred in general terms to the damage done by the heavy rainfall during the forenoon of Wednesday, May 29th. Serious as this was, it sank into insignificance compared with the devastation wrought by the down-pour of the night and early morning of the 30th. expected, communications were temporarily interrupted by road and telegraph with some of the out- As might be stations, and it took some days before even an approximate estimate could be formed of the condition of things. I will now endeavour to convey, as briefly as possible, a clear idea of the injuries sustained, and the remedial measures adopted.
15. On the morning of Thursday, 30th of May, I consulted with Mr. COOPER (who had acted as Surveyor General during the unavoidable interval which elapsed between the departure of my prede- cessor and my arrival). I should here explain incidentally that (as His Excellency is aware) the Engineering Staff of the Department was at the time owing to various circumstances, exceptionally weak, and in fact consisted of Mr. COOPER and myself, the two Assistant Engineers being away on leave. As the water supply from Tytam was cut off, and that from Pokfulam seriously threatened by land slips, there appeared imminent danger of the temporary interruption of the water supply to the City. It was therefore arranged that Mr. COOPER (who was best qualified from his practical acquaint- ance with the localities and details) should, under my direction, look after the water supply, while I undertook to do the best I could with the streets, roads, drains, &c.
16. Acting ou the best advice available I proposed to place the Land Surveyor (Mr. SAMPSON) charge of the work for clearing the streets of debris. After going over the City with him from east
to west on 31st May and 1st June, and giving him full instructions, I received, on the eve of the second day, the first intimation that it was his intention to resign his appointment. Mr. BOWDLER for many years Assistant Surveyor General, but who was prior to my arrival appointed Engineer of the Praya Reclamation, kindly offered his services, but it was deemed inexpedient, except there was an absolute necessity, to take him from the very important work on which he was at the time engaged. Under these circumstances arrangements were made with His Excellency the Major-General Com- manding, that the services of Lient.-Colonel CHAMPERNOWNE, R.E, should be placed, temporarily, at the disposal of the Public Works Department. This relieved me of a great difficulty, and admitted of an efficient organization of the work needed to repair the damage sustained. I may I trust be per- mitted to express my personal obligation to General EDWARDs, Ĉolouel Storer, C.R.E., and Lieut.- Colonel CHAMPERNOWNE for the readiness that was shewn to assist the Government, and this Depart- ment, in an exceptional emergency.
See noted at end of report.