IMPORTANCE OF FEDERAL HYDOGJRAPHY. XXIX. 



from Tenterfielcl on the north to Oooma on the south, and 

 now exhibits for what they are worth the diagrams of the 

 experimental plotting; it will be seen how very closely 

 the curve of rainfall conforms to the curve of altitude. 



Time did not permit of a fuller investigation of this 

 interesting question, but more data than the author had 

 at his disposal would be necessary to arrive at any result 

 regarding the ratio existing between increase of rainfall 

 and increase of altitude, it can only be said as Mr. Russell 

 puts it, that altitude is a material factor of the rainfall, 

 what that factor is, hydrography only can supply, but these 

 diagrams shew what great fields are open to the explora- 

 tion of the hydrographer. 



The question of river gauging, occurrence of floods, and 

 the determination of flood levels and stream discharges 

 taken in conjunction with the rainfall opens a very wide 

 door for enquiry and research. 



The Water Conservation Branch has done something in 

 this branch of the subject, and Mr. McKinney established 

 flood gauges in our western rivers, but only the fringe of 

 of the question has been touched, and that in a very dis- 

 jointed and fragmentary manner. In respect to flood gauges 

 it is feared we are worse off than for rain gauges, and yet 

 if, as is now generally conceded, it is important to know 

 the amount of rain that falls, how equally, nay, how much 

 more important it is to know the amount of rain that the 

 rivers discharge. For of the two, it is infinitely more im- 

 portant to engineers who are about to project water con- 

 servation or irrigation works to know what is the daily 

 stream flow measured over a long series of years than to 

 have an accurate record of the rainfall. For such purposes 

 the relation between rainfall and river discharge is often 

 useless, because some rivers discharge during the rainless 

 season a great deal more than the amount of rain that falls 



