Evening star., 1921-08-21


| curve there were scaled off the time
and height of each high and low wa
ter.
While this was a considerable ad-
vance. it still consumed too much time,
SO William Ferrel. one of the mathe-
! maticians of the coast and geodetic
survey. set to work, with the result
| that in 1888 he had perfected an in
vention which did away with the
necessity of scaling Off the time and
In the Ferrel machine both the time
and height of each tide are given
directly on the face Of the machine.
This machine filled the bill for about
quarter Of a century, but the grow
ing needs of the Navy and merchant
marine necessitated the prediction of
tide at many stations on the Pacific.
where the tide is quite complicated.
In 1910. two of the experts en-
ployed by the survey. Messrs. Shidy
and Harris. the latter now dead. con-
ceived the idea of machine that
would still further lessen the num-
Der Of computers apd would also work
Their IDEAS were outlined to Ernest
[aeoeg Fischer. chief Of the iustru-
Fment, division OF the survey. and the
machine was built under Mr.. Fischer's
personal supervision. This latter tide
predicter. which is .now in use. COM
bines the genius of the tidal mathe-
maticfan with that of the expert me-
chanicali engineer. 1t was devised.
designed and constructed in the home
Of the survey.
4 * X
once this machine is set for any
given station it is entirely auto
matte in operation. AS each succeed
ing high water and low water is
reached. the machine automatically
locks and on dials on the face of the
machine there is indicated the time
Of the tide to the nearest minute and
the height to the' nearest tenth of a
foot. A slight pressure then releases
the machine and when the next high
or low water is reached it again
automatically locks.
In coastwise navigation currents
are an important factor, for in thick
weather" the navigator cannot de-
al ghting on land objects: thus it be-
comes q matter of Importance that he
should know the strength and direc-
tion of the currents. The survey is
now making a study Of the currents
rents are Of totally different char
acter. Tidal currents are brought
about by the tide and go through
periodic changes. For years sailors
have taken it for granted that a wind
rection. and the stronger the wind
the stronger the current. The in
vestigation now being conducted by
the survey is bringing out the exact
relationships between the force of
the wind and the strength of the cur
he hos
been found to increase with the in
creased strength Of the wind: but the
direction of the current is found to.
be not in the direction of the wind,
but about twenty degrees to the right
of the &ind direction. The in-'
for a wind blowing parallel to the,
coast will not only affect the speed
OF a boat, but will also tend to set
it on the coast. @
tide machine, in order that the reader
may fully grasp its usefulness, 1t
should be stated that this device not
only has taken the place Of a hundred;
computcrs, but can do Its work amy
place. any time, anywhere; It can
more. 1t is used only to predict for
year or SO in advance because
there might be a change In the con-
tour of harbor, etc. Every nation
III tne WOrlQ mas TeQueSteu unlOTId>
tion regarding this instrument. which
has been nicknamed by the employees
Of. the survey "Old Brass Brains"
There is no other machine like it in
the world. The day the writer saw it
in operation it was predicting tides
for 1928 at Do Son Kua-kam, en-
trance to French Indo-China.
During the past fifty years numer-
ous vessels have been wrecked by
striking uncharted rocks. and it has
been a physical impossibility. to cover
more than SO many miles per year
with the meager force allotted to the
coast and geodetic survey.
\ kk
LIVER since gold was first discovered
II in Alaska interest in that won
derfully rich section Of the United
States has been maintained. A rail-
road costing sixty million dollars or
more is on its way to completion. but
the only way to get to the terminal
of that railroad is by water. Numer-
GUS rocks submerged, some three feet
below the surface. others at greater
depth. have been located. Many Of
these rocks are known as pinnacie
rocks. sharp pointed projections that
could be discovered only by chance
II the old fashioned method of sound $
ing was employed. but now. device
known as the wire drag Is employed
to locate these danger points.
hit an uncharted rock in
the main channel to New. Bedford
harbor. Upon close examination OF
the survey Of this body Of water It
was found that the soundings were
taken much closer together than was