THomson.—Glacial Action in Otago. 317 
rise 4,978; from whence the following comparison was made, with actual 
survey data :— 
Bv ELLIPSE. By Survey. DIFFERENCES. 
At source ne ri 0000 Xs 0000 G2 
Е š : 3548 e 3934 WE 386 
АРИНА рана | AS90260 e gay cen жүрү 
At exit to sea A 4978 eis 4978 su 000 
Again, taking the survey data of the Taieri River, we find the same 
conformity. This was less to be expected than in the preceding rivers, as its 
course is more than ordinarily tortuous, rising, in the Lammerlaw, at a 
distance of only 35 miles from the'sea, yet it has a total length of nearly 
128 miles. Here again, where the country is free from rocks and mountains, 
its bed approaches the ellipse ; where the course is obstructed by hard rock and 
precipitous hills, as in Strath Taieri, it is moditied in the manner due to the 
indicated cause. 
For the calculation of the ordinates we have: length of valley equal to 
640,920 feet, rise 3,820 feet ; from whence the following comparison was made, 
with the data given by actual survey :— 
By ELLIPSE. By Survey. DIFFERENCES. 
At source ic ai 0000 R 0000 Ж 000 
2476 з 26307: 3 144 
; s ; 2998 oa 2834 bed 159 
At intermediate points 4. $593 7" 3165 `. 358 
3116 3803 26 
At exit to sea 3820 3820 00 
So far encouraged, I next investigated the levels of the Molyneux or 
Clutha, using such points as had been settled by actual survey ; and here I 
first met with apparent non-compliance with my rising convictions. The 
properties of the Clutha appeared to differ from all other rivers yet investigated. 
Its course was seen to cross the great valley systems of this part of New 
Zealand, and its source would have more fairly belonged to the western slopes 
of the great backbone of the Middle Island than to the eastern. It passes 
through the Wanaka Lake (a painting of which is on the table, taken by me 
on its first discovery, in December, 1857) within 26 miles of its fountain, 
which I have placed in Mount Nix, but which might as fairly have been 
placed in Mount Brewster on the opposite side of the valley, or in Haast’s 
Pass, at the low elevation of 1,716 feet. Leaving the Wanaka it crosses the 
great hollow that stretches from Timaru, by the Lindis, Kawarua, and Dome 
Passes to Invercargill ; then it pierces the Dunstan range ; then it crosses the 
hollow of the Manuherikia and Pomahaka ; after which, piercing the Beaumont 
Gorge, it issues in the plains and delta near the sea. Thus, while its course 
runs counter to prior experience, its levels are also equally divergent. Tt will 
be observed that, though the divergence is more at the ordinate nearest its 
