The times. [volume] (Washington [D.C.]) 1897-1901, 1901-01-27

tached 10 this carriage, near the bottom
of the tank, was a horizontal plate of
glass. on which layer of sand was sifted,
of uniform quality and depth in all the
experiments made. The order Of nature
was thus exactly reversed; instead OF the
water oscillating over the bed of sand, the
bed OF sand was made 10 oscillate under
The water; but the principle, OF course,
remained the same. Over 100 experiments
were recorded. the glass being carefully
lifted out after each test. and blue print
made in the sun, directly from the sand
ripples, which develop with beautiful sym
metry on these plates. The results were
most interesting especially when com
pared as types with similar fossil forms.
one print shows the ripple marks caused
by two sets of oscillations, the second at
right angles TO the first. The effect sug-
gests the regular arrangement of fern
leaves without the stem. Leaving out the
ma thematics of the subject. the chief law
brought out was that the longer or more
frequent the oscillations the holder and
larger the ripple marks. measuring from
crest TO crest. became. Another point was
that after a ripple mark had become
,abiished. so to speak. under uniform con-
ditions OF oscillation, the duration OF the
oscillation had no further effect.
Experiments in other geological phe-
nomena have followed this study of rip
pie marks The synthesis of rocks is
shown by the actual manufacture OF such
substance which is In all respects ideni
cal with the natural rock. The contraction
of tne earths interior. and other forces,
bring a tremendous lateral pressure TO bear
on the lower strata. causing them to bend
upward and crumple in various well-rec-
ogniZed deformities This is illustrated in
The Harvard laboratory by subjecting lay
ers OF wax of different coloTs. to show
qualification to powerful lateral thrust.
after weighing them above to represent
the pressure which is usually brought 10
bear on such deformed beds By the over
lying strata. The result is gradual de-
velopmeR in the wax model OF folds and
fractures initiating the results that one
finds in nature in the same dynamic con-
aitions
, Another problem taken UP Is the intrn-
sion of lava chiefly through crevices aud
flaws into stratihod rock beds. where.
avoiding the harder limestones. IL makes
a final lohgment in the layers OF softer
composition. like shale. The body finally
makes a lenticular. or lens-shaped. form.
as Illustrated in the rounded porphyry
eninences of such district as the Black
Hills country of Dakota. In the Harvard
models the limestone beds are represented
by plaster OF paris and the shale by coal
dust. Into these layers is forced melted
beeswEx. which sometimes breaks out on
the surface in miniature volcanic action.
and sometimes finds It's place In layer OF
coal dust in the normal lenticular or
sheet intrusion" form
Erosion is another phenomenon which
il has been found possible 10 study by
this series OF dynamic experiments. Here
a tiny area Of land Is laid out To repre-
sent an actual structure of hard and soft
rocks of +he earth's surface. and the
whole is watered with a fine spray in or
der to observe the effect of rain and the
formation OF streams aud river beds upon
a piece CT country of definite structural
character. The difficulty in this expert
ment was TO produce iine enough spray;
a drop OF water of natural size" so 10
speak was so big that II produced havoc
In this miniature landscape. After mary
trials a suitable shower WAS finally OBJ