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

tanned. however, by DETECTING a rapid Jet
Of water on a bit of roughened tin, with
provision for protecting the model against
injury from the surplus drops.
Still another experiment concerns Itself
with geysers, which are made to spout
with rhythmical regularity, and to show
the effects of "soaping''-a method often
employed in the Yellowstone Park TO has
ten the time OF eruptioE-by the increased
activity consequent on the boiling water
becoming more yiscous and filed with
bubbles. But perhaps the most interest
ing OF all the Harvard experiments is the
one undertaken to show the formation
of sand delta plains by glacial rivers.
These deltas, usually more or less I'M
perfect from the action of wind and wealth
err are found over many parts OF the gla-
cial area of North America, and may be
seen in process of formation, to name a
well-known example. at the mouths of
some Of the glacial rivers of the Alaskan
coast. well-known ancient plain of this
character. dating from the glacial period,
is In Newtonyiile, Mass. z few miles from
CambTide. The glacial stream flowing
from beneath the ice is supposed to have
carried out and deposited successive lay
ers of sand, working its way back and
forth in various radial directions over the
low delta so formed in the sea or lagoon
is leaf-shaped. and when the ice OF the
glacier has melted away, a serpentine
stem or steep ridge appears-known as
the "esker" OF the delta-which marks
the sand choked channel of the original
stream that meandered in its cayerns be-
meath the ice. The sand of the delta is
in Iayers-as is clearly seen for instance,
in many railway cuts in the old sands Of
Massachusetts-each surface layer or bed
terminating in a steep slant to mark the
successive extensions of the front be nix
of the delta.
The appliance in the Harvard labora-
tory consists of piece Of lead bent into
the general shape of a glacier over an
artificial tin cavern. and set in a tank of
water. with a hose supplying the glacial
stream which is fed through funnel
with alternate coal dust and marble dust
for sediment. TO indicate distinctly the
layers deposited in the little lagoon. The
apparatus has worked perfectly, the ex-
periments giving variations in the forms
OF the deltas according as the water was
maintained at a higher or lower level, but
always showing the characteristic front
and surface deposits with clearly defined
beds. Moreover. the experiments have
gone far toward explaining one of the
phenomena of these sand plains which
had not previously been well understood
The sand plains of New England are
found to be somewhat out of the normal
in that as is shown in railway cuts, the
frontal beds are often truncated-cut
sharply off, that is. from any apparent
connection with the upper, fiat-lying de-
posits OF the glacial period. DR.. Jaeger
: found from his experiments that this
must nave been due to fall in the level
of the lagoon in which the sand bank had
been formed, since the lower slipping beds
could have their upper limits cut of by
no other possible cause. When the
lagoon lowered. the glacial stream would
cat down 10 the old frontal deposits that
had been formed beneath the water when
il stood at higher level. Thus planned
OFF by the stream. the deposits of the old
front wall we're replaced by the sands
and gTayels Of the new stream. so that II
oss-seetiop shows steepy inclined beds
below. truncated ny fa. ones above