Van Yean Water TVoi^ks, 



189 



still water, This swamp was composed of vegetable matter 

 to an unknown depth, and so boggy, that a fencing rail was 

 forced into it by one man to a depth of five feet ; the flow of 

 water at this point was so trifling that it could not be mea- 

 sured, and was probably all evaporated before reaching the 

 junction with the eastern arm. From minute inquiries we 

 learnt that this swamp extended two and half miles further 

 up, making in all four and half miles of swamp, averaging 100 

 yards wide, thus exposing 787,000 square yards to surface 

 evaporation. We did not follow this arm up to its source, 

 but we feel satisfied that it affords little, if any, supply to the 

 Plenty during the summer months, and on this occasion none. 



AVe then proceeded to examine the eastern arm, wliich 

 also flows, with the exception of a slight divergence, through 

 a swamp, for two and a half miles above its junction with the 

 western arm. This swamp is two and a half miles long, and 

 averages 700 yards wide, having, therefore, a superficial 

 extent of 3,000,000 square yards; it is charged with w^ater 

 from the eastern arm, and is in some places less boggy than 

 the western arm, and the flow of water through it has a more 

 defined channel and consequently has a less proportionate 

 evaporation. We measured this discharge about two miles 

 up, and found it to be 712 cubic feet per minute, the surface 

 velocity being lO'lS inches per second, and sectional area 14 

 square feet, the mean velocity being obtained, same as in 

 former case ; it is thus 1 1 times the discharge of the Plenty, 

 where previously measured at aqueduct below the swamp j 

 thus showing, that at that time 43 per cent of the discharge 

 was lost by evaporation in the swamp. 



Our next subject of inquiry was relative to the source 

 from which the lliver Plenty derived its supply in the summer 

 months, as it was perfectly evident that there was no siu^face 

 drainage into it from its basin, excepting after heavy rains, 

 the surface of the ground being quite dry, and the eastern 

 arm the while discharging a strong current of water ; to this 

 end we determined to follow up the eastern arm to its source. 

 Proceeding accordingly, we crossed Jack's Creek, which is a 

 fine tributary to the eastern arm, and through which a consi- 

 derable volume of pure water was flowing; and pursuing the 

 eastern or main arm, we crossed the Sugar Loaf Creek, 

 which is another small tributary of good water being now at 

 the foot of the Ranges, we again crossed the eastern arm at 

 the Ford, and commenced ascending up a deep gully or gorge 

 down which it flows. This gnlly is clothed with verdant and 

 dense vegetation, consisting of tree-ferns, &c., increasing in 



