1 
9 
even now wholly exploded, bufc geologists 
are generally satisfied to seek in existing 
causes a sufficient agency for the purpose, 
though it may be admitted that change of 
climate or other circumstance may have in 
some cases had more or less influence. It is 
only the continued action through long ages 
of comparatively small forces that is really 
efficient to produce such results. But there 
is a circumstance which appears to me to 
have been largely overlooked by geologists— 
that is the immensely heightened effect of 
water when charged with mud. When you 
see the ordinary little clear brooklet trick¬ 
ling along the bottom of its valley it seems 
incredible to you that so small and feeble a 
thing should be able to scoop out that- 
eomparatively large and wide ditch. And 
ordinarily when the water is clear the erosion 
of the stream is really nil or almost so and 
is chiefly confined to carrying off matters 
such as lime, etc , held in solution. But -when 
the heavy rains of the wet season come and 
the swollen river with its waters charged 
with mud rushes down, the quartz boulders 
are rolled along like mere trifles and large 
quantities of sand and gravel are carried 
away ; in the process eroding the 
banks at every turn and thus secur¬ 
ing a fresh supply of detrital matter. 
The operations of the apparatus used in 
alluvial gold-mining and calledthe “longtom” 
are interesting when viewed in connection 
with the effects of water holding mud in 
suspension. This apparatus consists of a 
wooden trough about 18 inches or two feet 
wide and nine or ten or more feet long, its 
lower end closed by an inclined metal plate 
pierced with holes of about an inch in 
diameter. Underneath this perforated plate 
is placed a box called the|“ ripplebox” con¬ 
sisting of two or three divisions supple¬ 
mented perhaps by a blanket or a small 
trough containing mercury} the object being 
to retain any gold that may have passed the 
i ipplebox The way of working this appaia- 
tus is for the gold-bearing stuff to be placed 
at the upper end of the trough which is 
slightly inclined ; a stream of water is then 
directed upon, it and it is stirred up with 
hoes. This causes the mud and clay to l e 
quickly carried away, the water passing 
through the holes in the plate and carrying 
the finer gravel and sand into the ripple box, 
where the particles of gold fall to the bottom 
and are retained by the divisions of the box 
which is filled to a depth of two or three 
inches with sand and gravel. As long as 
muddy water flows into and through the 
