The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1896-08-07

/ JQlnS. PerndpS the DeSt way 10 90 tQdL
/ is TO get them TO find specimens of
rock, etc. Do not describe or call at
tention to the peculiarities of the spe-
/ cimens at first. Have them squared.
! This can be done by chipping off the
| corners with a hammer Label them;
! that is, tell first of all where they are
! found, and perhaps when. a quarry is
/ a good place TO find specimens, because
/ you can there get below the surface of
/ the ground. When the interest is once
/ aroused, begin TO say, this is a good
/ specimen because it shows something
/ for instance, has a vein of different rock
running through it. (Here the profess
/ sor held up a specimen.) 1t is not hard
to find good specimens; l picked this up
| this morning before breakfast.
| The rocks are not all, however, nor
! the most important part, for them TO
consider. The soil is the more import
| ant part, though it is usually only
| few inches or feet thick. Take buck
! etful Of ordinary soil, cover it with
water, stir it up until it is muddy, and
pour off the muddy water. Then exam
| inc the residue. If you examine il
| closely, especially with a small micro
| scope, you mill see that it is made up
| of sand 1t is we'll to pour off the mud
| dy water into another vessel, say a tub,
and allow it to settle. The soft, fine
| residuum should also be examined care
| fully. If the boys haye brought bottles
or cans of sand from the sea shore
which should be dOne-these parts Of
the soil can be compared with the diff
| ferent kind of sand.
Your pupils should then be encour-
| aged to think about where they find
sand, how it gets there, why sand and
| fCr SYS 10 o6S
| of streams and the silt is absent. An
experiment may be tried in this line
| if you have water works, by turning on
| the water from a hose for twenty-four
| hours or so and then examining the
work of the water. Those who are not
so fortunately situated will have to
wait for a rain. You will find in either
case that the water has cut out a little
| channel has deposited here coarse
gravel, there sand yonder silt. Why?
| Because here the water ran swiftly and
only the heavy gravel was dropped;
| slowly yOnder and only the finest of the
sand carried past The pupils should
be encouraged to discover this for
| themselves.
Examining the soil further, you will
| discover that in that from some places
| the sand has sharp edges, in others
round Why? The round has evidently
been moved. This has sometimes been
done to an enormous extent. The soil
of Michigan, for instance, was moved
south for hundreds of miles.
Another difference you will discover
is in color. The prevailing color in
many localities here is red. That is
from the iron in the soil being OXidized.
Where there is much Vegetation, how
ever, the soil is black
1.-The vegitaton has taken away the
oxygen and so the soil turns back to
black, its natural color. Soils are also
sometimes white. This usually indi-
Gates lime.
1.-The most important distinction
however, is that first indicated, i. e..
that of texture Soil may be coarse,
i. e., sandy; sticky, that is clayey; or
loamy, from decomposition of plants,
etc, the product being similar to char
coal, but the process much slower.
I'm most countries you would find on
close examination of the residue left
by washing that it is small particles of
quartz. Here, however. it usually con-
sists of real crystals, left by the de-
composition of lava, and called Divine.
The black sand may, however, be a
compound of iron, which may easily be
removed because it is attracted by a
magnet, and hence is called magnetic.
You will find in this much to inter
est you, and your pupils will also be
greatly interested if you are. 1t should
be followed by the study of water in
streams, its work, etc.
GAS to the minerals, study them now.
and encourage your pupils to study |
them. In most places they are all lava
in different forms and stages. Homo |
lulu, however, is very fortunate in nav
ing a variety. Some specimens will be |
full of holes, some have only a few |
large ones, and some none. Lead pupils |
TO discover that the cavities were made |
by steam.
You may give them the terms vas |
sular and compact if you like, or per- |
fOrated, any term that describes; but |
be sure they have some word, because |
the word helps the mind and memory. |
There will be two classes of rock at |
once perceptible that which assumed |
its present form through being melted. |
and that which did not. The latter is |
partly sandstone. partly tufa. On study |
ing the latter you discover at once it is |
made of black sand. In some specimens |
this is ready TO crumble at touch: 9TH |
ers are more solid. The sand is dis !
covered to be fragments of lava. There |
must have been some tremendous eX-
plosion to blow the lava into such |
small pieces. The force was steam.
The water got into the lava, and in
blowing out wore away the cooler up
per crust like a sand blast. This set
tied on the slopes. The steam cooled |
and fell in torrents or rain. carrying
with it the sulphur vapors in the at
mosphere. The latter through chemical
action cemented the sand and made the
rock as we find it.
I'm all this work you will find much
that you will not understand at first.
some perhaps that you will never I'M
derstand So you can keep thinking
while your pupils are thinking. In
answer To q n11esrinn from Mr. Town |