195 
a view to determining their permanence, volume and utility, and 
finally the wells are analyzed for a like purpose. 
The theoretical amount of water available is discussed at length 
from the annual rainfall. The precipitation is disposed of in 
three ways : First, a relatively small part is lost in evaporation ; 
secondly, a large part is absorbed by the soil, and continually 
moving, sinks down to the surface of permanent saturation (all 
of this water finding its way eventually to the shore and emerging 
at or about sea level), and thirdly, a part rims off in living- 
streams. 
The utilization of the water supply of Molokai is now dealt 
with and the problems involved in increasing the water for irri- 
gation purposes is discussed in a practical manner. The question 
of reservoirs, tunnels, pumps and flumes is also discussed and 
many valuable suggestions are advanced for conserving the water 
supply for economic purposes, including its use for the develop- 
ment of electrical power. 
Altogether the article referred to is a most interesting one, and 
contains much thoughtful matter which is particularly valuable 
to those conversant with island conditions. Admirable illustra- 
tions add to the utility of the work. It is to be regretted, how- 
ever, that the established usage of Hawaiian and other ortho- 
graph has not been adhered to, for the rendering's 'manania' 
for manienie, 'eea' for ieie and 'lantania* for lantana come as 
somewhat of a shock to the kamaaina. 
The Water Resources of Molokai, Hawaiian Islands, by Walde- 
mar Lindgren, forms Water-Supply and Irrigation Paper Xo. 77, 
Series O, Underground Waters 19 of the publication of the U. S. 
Geological Survey, Washington. 
PRICKLY PEAR A MOSQUITO PREVEXTIVE. 
The most important practical discovery in dealing with the 
mosquito nuisance since the action of kerosene was understood 
has been made by a French physician, M. Sanzeau de Puyberneau, 
who has found that the leaves of the common prickly pear if 
chopped up and thrown into water will prevent mosquitoes breed- 
ing in the water for weeks if not months. The resinous mucilage 
of the leaves floats on the water surface and chokes the breathing 
tubes of the mosquito. Further, in stagnant foetid water the 
prickly pear juice has the property of absorbing the gases of de- 
composition. It is most important that as extensive a trial as 
possible may be made of this new method of mosquito prevention 
in the Zanzibar Islands. The prickly pear is everywhere, and 
very little trouble is needed to chop up the leaves and drop the 
pieces into water, which formerly had to be repeatedlv kerosined. 
— Zanzibar Gazette, April 29. 
