CaupsELL.—Draining of Towns. 29 
surface, and remains at blood heat until December, when it fills up, a 
strong outflow takes place, and the temperature is increased to 204°. 
I earefully noted these springs during the years 1870 to 1874 without 
detecting any deviation from what I have already stated. 
In writing these notes I have had to trust entirely to memory : they are 
. therefore not so accurate as might be desired. But I think sufficient 
evidence has been adduced to justify us in assuming that the coincidence 
of these changes in the Hot Springs is not merely accidental, but must 
be attributed to some unexplained eause. Before any correct theory can be 
arrived at as to the supposed effect of the wind on the Hot Springs, it will 
be necessary to obtain careful observations extending over a considerable 
time. 
Can it be that the singular phenomena I have alluded to are caused by 
contraetion or expansion of the earth's crust? or are they attributable to 
barometric pressure? It seems difficult to realize the possibility of their 
being due to the latter cause, as the orifices of some of the springs I have 
instanced vary in width from 90 feet to nine inches. 
Were these geysers situated at a lower level than the lake, atmospheric 
pressure, extending over a large water surface, might readily be assumed as 
a cause ; but Te Tarata, and several of the springs I have mentioned, are 
at a considerable elevation above any water. 
Before concluding, I may mention that volcanic action in the Hot Lake 
District is fast dying out. Many of the finest geysers have dried up during 
thelast twelve years, including the once famous Waikite, at Ohinemutu— 
so graphically described in Mr. Meade's book— Waikite, at Whakarewarewa, 
and Te Koingo, or the ** Sigh," at Rotomahana; while few new ones ever 
burst out. 
Art. IV.—On the Draining of Towns. By W. D. CAMPBELL, 
Assoc. Inst. C.E., F.G.8. 
[Read before the Wellington Philosophical Society, 4th November, 1876.] 
Tux subject of drainage comes before us, in almost every town, either as a 
question of system or of clarification at the outfall; in England, both of 
these aspects of sanitary work have of late received a great deal of atten- 
lion, and many of even the most lethargie towns have been stirred into 
action by injunctions served upon them by River Conservancy Boards. 
The consideration thus bestowed upon drainage has necessarily caused 
a more methodical grappling with the subject; and the author having been 
actively engaged for several years upon drainage works, submits to the 
