409 
principal springs more in detail with a view of furnishing a guide 
to the numerous visitors of the lake. 1 
The Rotomahana is one of the smallest lakes of the lake 
district, not even quite a mile long from South to North, and only 
a quarter of a mile wide. According to my measurement it is 
1088 feet above the level of the sea. Its form is very irregular, 
on the Southside, where the shore is formed by swamps , three 
small creeks are meandering and discharging themselves into 
the lake, the Haumi from Southwest the Iiangapoua from South- 
east, the middle creek without a name. In many places of those 
swamps warm water streams forth; hot mud-pools are also visible 
here and there; and from the projecting points muddy shallows 
covered with swamp-grass extend almost as far as the middle 
of the lake. At its Northern! the lake grows narrow, and where 
the Kaiwaka creek flows out, there are again on both sides noth- 
ing but grass-swamps and shallows. Only in the middle the water 
is deeper; and the shores East and West are high and rocky. 
It justly bears the name of “warm lake.” The quantity of boiling 
water issuing from the ground both on the shores and at the bot- 
tom of the lake, is truly astonishing. Of course, the whole lake is 
heated by it. Rut on making attempts to ascertain the temperature 
of the water, it is soon found to be very different in various places. 
Where the rising of gas-bubbles indicates a hot spring at the bot- 
tom of the lake, the thermometer will be often seen to rise to 
90 or 100° F. Near the mouth of the cold creeks, the water of 
which showed a temperature of 50 to 52° F. , the temperature is 
found to be only 60 to 70° F. ; but in the middle of the lake and 
near its outlet 80° F, may be considered as the mean temperature 
of the lake. In bathing and swimming through the lake, the 
change of temperature is very easily felt; but care must be taken 
not to come too close to any of the hot springs. The water 
1 A detailed map of the lake, upon which the various springs are marked, I 
• have published in Dr. A. Peterniann's Geographishe Mittheilungen , 1862, as well 
as in the Topographical and Geological Atlas of New Zealand, 1863, and in the 
Geology of New Zealand, 1864. 
