Evening star., 1923-04-29
Depths of the Sea Now
Measured by Sound

pulse with the transmitter and
measuring with a stop watch tn"
lapse of time before the echo of that
impulse is heard in the receiver. Con-
sidering the velocity of sound to H.
$500 feet or 500 fathoms. the dis
tance the sound travels to the sea
bottom and back will be the equal t.
the number of seconds, shown on tn"
stop watch, times 500 fathoms The
depth would be equal TO one half ~
that amount.
THERE must be taken into consid-
L GRAFTON, however, the human -
ror in starting and stopping tn.
watch, so experiments were conduct
ed with a patented device which con
sisted of constant speed mechanism
which could be set in motion by th.
outgoing impulse. and. by means of ;,
delicate relay system, was brought H.
rest by the received echo, thus indI-
eating. without human error, th..
time interval desired. 1t was fourI
that even this method was not IS
practical as was desired, as the r.
lays could not be kept in proptt
adjustment, and that the device Wa
! brought to rest by various subaqus-
Gus sounds other than the echo -
the sound transmitter signal. Aas
Old-time men of the seas wou
have considered the results so far
obtained as being sufficient. but not
the modern navy man. so the Nav :
devise an indirect means of measur-
ing the time interval which employed
no sensitive relays and produced re
suits that were correct within .0H,
per cent. The design of this device
depends upon the principle that. II
sound impulses are sent out at vari-
Gus known intervals, some one "f
these intervals will agree with the
lapse of time necessary for the sound
to travel to the bottom and back IL
the receiver.
Thus it will be noted that the final
design of the Sonic depth finder
based upon the theory just stated.
consists of a continuous speed rotary
converter, controlled. over narrow
bands of speeds. by tuning fork. :,
disk of ten inches radius. rotated Al
slow speed by the motor of the rotars
converter; shaft upon which the
rotating cams are mounted and which
carries a friction wheel which can he
adjusted to rest, at any radius Gen
inches or less). on the rotating dis
keys which are operated by the cam
wheels for sending sound transmitt"r
signals; inductive coupler for cor
Meeting one phone inductively to tla-
sound transmitter circuit; necessart
wiring TO connect opposite phone nf
the head set to sound receiving ar
paratus; a divided head telephone 81
of low resistance; an adjusting screw
for the friction wheel. having 4
micrometer scale.
1t should be mentioned al this poitlt
that the sound receiver with this d,
vice, which determines direction ~.
curately. is matter that is confideu-
tfaI and cannot he described II Is
Navy secret
WHILE the depth finder is srea'
inc that 1t is a complete means in
itself for mea suring depth or shallow
places. In the former case it is neces
sary to use, with the depth finder. 4
hiRh-power yibratory sound trans
mitter, so we find that it is oonsid
cred feasible to use the Sonic depth
finder in conjunction with sound
transmitter and directional sound re
ceiver for measuring depth, determin-
ing the contour of the sea bottom and
| In some cases determining the dis
| tance of the seacoast.
The maximum depth measure dc
pends upon the efficiency and power
of the transmitter. Depths UP To
| a.200 fathoms t19.2o feet) have been
measured with the depth finder by naval
| vessels.
Tia tJpitAN 2tatAS hA4 more large