XIV 



through the straits, formed by the re- 

 markable peninsulas — locally called 

 ''necks" — which are characteristic fea- 

 tures of the lake, a rise of over a foot 

 takes place at the extreme ends, after a 

 moderate gale only. This does not affect 

 the question before us, but it was thought 

 it might be a fact of interest to th© Fel- 

 lows of the Society, 



The gauging of the streams was taken 

 with a current meter, kindly lent us by 

 the Government Hydrographer of Ncav 

 South Wales, Mr. Halligan. Sections of 

 the stream beds were carefully taken, a 

 site being selected in each case where the 

 bottom was even, and in the case of the 

 larger streams the current v:as taken at 

 the surface, a foot below it, and near the 

 bottom, and the mean taken as the ve- 

 locity. 



Wiiere it was not practicable to measure 

 the depth at intervals right across, the 

 depth in the centre was estimated propor- 

 tionately with that near the sides. In 

 every instance care was taken not to over- 

 estimate the depth, so that the calculated 

 volumes may be taken as rather under 

 than over the actual ones. 



It was thought advisable to ascertain 

 the quantity of water the "feeders" at 

 the north end were capable of supplying 

 to the Lake; we, therefore, decided^ to 

 gauge them shortly after the flood of the 

 3rd March, alluded to above. A com- 

 mencement was made with the "^chanuer"' 

 the following day, 22 hours after the fresh 

 was at its height. 



The following table gives the result of 

 our measurements: — 



Channel from Little Lake. — Time after 

 height of flood, 22 hours. Velocity per 

 minute, in feet, 156. Volume in gallons 

 per minute, 66,812. 



Breton's Rivulet, 24 hours, 150ft., 31,171 

 gals. 



Kimberley's Creek, 27 hours, 140ft., 

 6,344gals. 



Pine Creek, 28 hours, 147ft., 34,912gals. 

 Brandum's Creek, 29 hours, 86ft., 2,150 

 gals. 



Total flow in gallons per minute, 141,- 

 339. 



Total flow in gallons per 24 hours, 203,- 

 000,000. 



The following day the Shannon Eivulet 

 was gauged about the Little Lake, to as- 

 certain the quantity of water flowing in- 

 to the latter from this stream, exclusive 

 of tliat from the many small rills inter- 

 secting the marsh land at the foot of the 

 Fluted Tier, overlooking the lake. The 

 Little Lake channel was also gauged. The 

 following were the results: — 



Shannon Eivulet— Time after height of 

 flood, 4S hours; velocity per minute in 

 feet, 130; volume in gallons per minute, 

 46,919. 



Little Lake Channel, 46 hours, 127ft., 

 48,218gals. 



On Saturday, the 7th, the fourth day 

 after the flood in the north, we gauged 

 the Shannon below the dam. Some diffi- 

 culty was experienced in getting a good 

 section, owing to the stony nature of the 

 bottom. We chose a spot where the river 

 was 24ft. wide, ond the depth 9in. The 

 result was as follows: — 



Shannon River — Time after height of 

 flood, 4 days ; velocity per minute in feet, 

 84; volume in gallons per minute, 9,450. 



Total outflow in gallons in 24 hours: — 

 13,848,000. 



We ascertained from the police trooper 

 in charge of the meteorological station at 

 Swan Bay. that the flood we had in the 

 north had made very little difference to 

 the lake level at the south end. It was 

 estimated that the fresly would have tak- 

 en about two days to reaxh the south, ac- 

 cording to which our measurements would 

 have taken about 48 hours after flood, al- 

 though the actual date gives four days. 



The conditions which affect the water 

 supply of the Great Lake may, therefore, 

 be summarised, in conclusion, as follows: 



1. A wet climate at the north end, caus- 

 ed by the proximity of high mountains. 



2. A watershed of mountain rivulets, 

 which sud..denly rise after torrential rains, 

 and which flow through morass-land, hold- 

 ing large ciuantities of water in wet 

 weather. 



3. Repeated heavy falls of rain, which 

 renew the large flow in the creeks, and 

 compensate for the rapid subsidence of 

 the iioods. 



4. Melting of ?now, particularly at the 

 north end. 



5. The ftormo.lly small ontflow at the 

 south end, owing to the conformation of 

 the land at the river's starting point, and 

 to the fact of its being dammed as well. 

 This small outflow will compensate con- 

 siderably for evaporation in the summer 

 season. 



Although the question of the lake water 

 being utilised largely as o.u irrigation sup- 

 ply is beyond the provinces of staring that 

 we take this opportunity of stating that 

 in our opinion the shallowness of the 

 lake, in spite of its large area, and the 

 intermittent nature of its source of sup- 

 ply preclude the carrying out of any ex- 

 tensive scheme without interfering with 

 the features of the lake, unless an em- 

 bankment were thrown a.cross the glade 

 through which the Shannon commences 

 its course. 



The conditions which lead to this as- 

 stimption are: — In the first place the lake 

 is uniformly shallow; its three great sub- 

 divisdons^— North Lake, East Bight, and 

 South Lake— are, on the bottom, level 



