( 13 )
At 10.5 P.M. No. 2 was started and went direct through the Lyemun Pass arriving at the Pass in one hour; its course is indicated by a blue line.
At 1.20 P.M. No. 3 was started; making but little progress eastward it was carried on the flood through the harbour as far as the Canton Wharf returning thence as far as Causeway Bay on the following ebb tide; its course is indicated by a green line.
At 3 P.M. No. 4 was started on the commencement of the flood, and after passing North Point on the flood tide followed practically the same course as No. 1.
At 4.45 and 6.15 P.M. Nos. 5 and 6 were started and left afloat till the night of the 22nd. No. 5 would probably, on the following ebb tide, pass North Point, and No. 6 would follow somewhat the same course as followed by Nos. 1 and 4. The course of each of these floats is indicated by green and blue respectively.
At 8.15 A.M. August the 22nd No. 1 was started off Belcher's Point and took an easterly course past North Point; on the following flood it drifted back a little to the west of that Point and would probably have got into the mid-channel cur- rent on the following ebb and been carried through the Lyemun Pass; its course is indicated by a brown line.
At 10.15 A.M. No. 2 was started and after progressing down the Sulphur Channel for some distance returned on the half ebb, arriving off the Canton Wharf at 10 P.M.; at the end of the flood it would take a north-westerly course and would probably be carried thence up towards the Canton River on the next flood, passing out west of Green Island on the following ebb; its course is indicated by a red line.
At 12 o'clock No. 3 was started. Taking an easterly course it reached Yau- mati bay at 6.10 P.M., and after sweeping round on the flood in a south-westerly direction it took an easterly course arriving off the Canton Wharf at 10.35 P.M., at which hour the commencement of the next ebb would probably take it eastwards past North Point; its course is indicated by a green line. At 2.25 P.M. No. 4 was started and travelled eastwards slowly; its course is indicated by a blue line. At 5.40 P.M. No. 5 was started on the flood tide but made little progress; its course is indicated by a red line.
With respect therefore to a sewage out-fall at North Point it appears from these experiments :---
(i.) that during both the North East and South West Monsoons there is a strong tidal current tending to carry all matters held in suspension in the waters of the harbour at or about North Point through the Lyemun Pass during the ebb tide, and that this tendency extends as far as Kowloon Point during the North East Monsoon. (ii) that during the North East Monsoon the flood tide sweeps through the harbour and effects a general dispersion of all suspended matter, and that there is also a strong current round Kowloon Point towards the South of Stonecutters' Island.
(iii.) that during the South West Monsoon the general tendency of the flood tide is to carry suspended matter from North Point through the harbour towards the mouth of the Canton River.
And with respect to a sewage out-fall at Belcher's Point it appears from the experiments:--
(i.) that during the North East Monsoon the ebb tide will probably carry
all suspended matters out to sea to the south of Green Island.
(ii) that the flood tide has little effect at this Point either during the
North East or South West Monsoon.
(iii.) that during the South West Monsoon the ebb tide sets in an easterly
and north easterly direction.
From the foregoing I am of opinion, considering the depth of water and strong tidal currents that exist in the harbour during the whole of the year leading to the general dispersion and mixing of all foreign matters with the tidal waters, that no nuisance will arise from the placing of sewer out-falls at Belcher's and North Points, and it is on this account that these two Points have been selected as suit- able out-fall stations.