318 



Transactions. — Geology. 



By Ellipse. 



By Survey. 



Differences 



0000 



0000 



000 



5050 



8127 



.. 3077 



7405 



8477 



.. 1072 



8084 



8601 



517 



8670 



8890 



220 



8781 



8929 



148 



8886 



8951 



65 



9101 



9101 



00 



source, yet this principle prevails that the curves gradually approximate, 

 showing that had the source been accepted at a lower point than Mount Nix, 

 the law would have been vindicated. 



For the calculation of the oixlinates of an ellipse for the valley of the 

 Molyneux, we have : the length equal to 944,040 feet, rise 9,101 feet. 



At source 



At intermediate points 



At exit to sea 



The next valley that the maps of the Survey Department enabled me to 

 examine was that of the Cardrona, a rapid mountainous torrent flowiug into 

 the Molyneux near to its issue from Lake Wanaka. The length of the valley 

 is about 31 miles, and the rise, from the Molyneux to the Crown Mountains, 

 4,799 feet. This example, considering the featvires of the mountain distiict, 

 shows a tolerably near approximation to the ellipse, as given below : — 



By Ellipse. By Survey. Differences. 



At source 0000 ... 0000 ... 000 



3433 ... 3923 ... 490 



3609 ... 4000 ... 397 



At exit 4799 ... 4799 ... 000 



The last example with which I will trouble you is that of the Mataura, 

 with its east and west bends, a painting of whose scenery is on the table, taken 

 on its first exploration, in January, 1857. The east branch being the shorter 

 is not properly the main river ; it will thus be seen that its curve is not so 

 near the ellipse as the other, but both are exceptional to the general rule, and 

 curve more under the classification of the Molyneux ; the western branch 

 crossing the low. depression already mentioned that stretches fiom Timaru to 

 Invercargill, and both crossing the remarkable valley that stretches from 

 Molyneux Bay to Lake Te Anau. Thus the features of its bed have the same 

 remarks applicable as have been made in regard to the Molyneux. The 

 comparison of the east branch gives the following results :— 



At intermediate points < 



At source 



At intermediate points - 



I 

 I 



At exit to sea 

 and the west branch, as follows :- 



By Ellipse. 



By Survey. 



Differences, 



0000 



0000 



000 



3201 



4547 



1346 



4216 



4773 



557* . 



4620 



4905 



285 



4904 



5009 



105 



5110 



5129 



19 



5173 



5160 



13 



5224 



6224 



00 



