Improvements in Instruments or Apparatus for Sounding or Measuring the Depth of Water.
Year: 1891

page_text: Date of Application, 21st Apr., 1891-Accepted, 6th June, 1897
Improvements in Instruments or Apparatus for Sounding or
Measuring the Depth of Water.
I, GEORG ADOLPHI RUNG, of St. Kangensgade 85, Copenhagen, Denmark,
Retired Army Captain and Subdirector of the Danish Meteorological Institute in
Copenhagen, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This invention relates to improvements in instruments or apparatus for sounding
or measuring the depth of water.
When a tube closed at one end is immersed mouth downwards in water, the
water will enter the same and thereby compress, or diminish the volume of the air
in the tube. This space filled by the compressed air will according to Mariotte's
law vary in inverse ratio to the pressure, the temperature being constant. In
consequence of this the actual alteration in the volume of the air does not
correspond directly with the depth to which the apparatus is immersed. Different
forms of apparatus have been designed by Sir William Thompson and by others
for measuring depth by the compression of air in a tube and are so constructed
that it is possible after the apparatus has been drawn up, to observe how far the
water ascended in the tube contained therein. However, as the divisions of the
scale for successive depths become smaller and smaller, the measuring of single
metres or of small differences in depth very soon becomes impossible. In fact it is
impossible with such apparatus to measure depths of over two hundred metres in
a satisfactory manner.
There is however another way of utilizing Mariotte's law, whereby it is possible
not only to employ a scale having divisions of equal size but it is also possible to
measure any depth of water. This method is based on the fact that the density of
air is simply proportional to the pressure.
The instrument or apparatus for measuring depths constructed according to this
invention carries with it a quantity of air, sufficient for all depths, enclosed in an
air chamber, this air being compressed during immersion to a degree proportional
to the depth. When the bottom, or the desired depth is reached, a certain constant
volume of the compressed air is cut off. The compressed air cut off in this
manner is then allowed whilst the instrument is being drawn up or afterwards, to
expand in a measuring tube, where its volume under the pressure of the atmosphere
after the instrument has been drawn up, can be read off. This latter volume will
be proportional to the depth to which the instrument has been immersed and thus
serves as a measure of the same. Whilst the instrument is being immersed or
sunk in the water the measuring chamber for measuring the aforesaid constant
volume of air is in communication with the air chamber, and is shut off from the
measuring tube which is filled with water; but when the instrument is being drawn
up, the measuring chamber is shut off from the air chamber and at the same time
or after drawing up, it is placed in communication with the measuring tube.
The communication between the measuring chamber and either the air chamber
or the measuring tube may be controlled by means of cocks, valves, or slides of
different kinds, operated by the instrument striking against the bottom, by falling
weights along the sounding lead line, by propellers or vanes, by the difference of
the water pressure in its action during the ascent and descent of the instrument, or
even by the force which is capable of being exerted whilst the instrument is
being drawn up by an amount of air compressed in a space provided for this
purpose.
Different scales or values for the divisions may be obtained in one and the
same apparatus, either by varying the volume of the measuring chamber or varying
he cross section of the measuring tube.

page_text: The details in the construction of the apparatus may be varied considerably ;
the following features being usually present :
1. An air chamber in which the air is gradually compressed by the pressure of
the water, whilst the apparatus is being immersed or sunk in the water;
2. A. measuring chamber in which a certain volume of the air compressed by
the water is measured off and shut off' when the apparatus has reached the depth
of water to be measured.
3. A cylindrical calibrated measuring tube composed of a glass tube, which
during the immersion or descent through the water is kept filled with water, being
then open at both ends, the said pipe being however first closed at the top as soon
as the apparatus begins to be drawn up, and being then placed in communication
with the measuring chamber during or after the drawing up, so that the compressed
air in the said measuring chamber will expand into the measuring tube and will by
its expansion drive a corresponding quantity of water out at the lower end of the
same. Along the measuring tube are provided divisions corresponding to different
depths of water.
In the accompanying drawing,
Fig. 1 is a vertical central section showing the parts in the position they occupy
during the sinking of the apparatus,
Fig. 2 is a similar view showing the parts during the raising of the same, and
Fig. 3 is a side elevation of the apparatus.
Figs. 4 and 5 are vertical central sections of a modification of the apparatus,
hereinafter referred to.
Similar letters refer to corresponding parts.
h
The air chamber is formed by a rubber cap which is fastened to the perforated
piece a by means of a protective casing c. This cap is of such a nature that it
will be compressed by a very slight pressure but will immediately expand again of
itself as soon as the pressure is removed. In the protective casing c which is
provided at top with an eye or ring d, for the purpose of attaching the apparatus
to the end of the sounding lead or line are suitable lateral holes through which
the water can enter in order to act upon the rubber cap b.
The measuring chamber is in this case formed by a recess in the one side of a
cock or plug inserted in the perforated piece a. The measuring tube / is inserted
with its scale i in a second protective casing n which is attached to the lower end
of the piece a, said casing n being cut away or perforated on the front side, as
shown in Figs. 2 and 3, so that the glass tube and its scale i can be seen, and
being also provided below with a ring for the attachment thereto of an ordinary
sounding lead. In order to facilitate the entry of the water into the measuring
tube, the casing is further provided in its lower part with a lateral opening above
which is an inclined guard p which facilitates the entry of the water during the
immersion or sinking of the apparatus. The water passes through the U-shaped
passage into the glass tube, and the air in the same escapes at the same time at
the top through the passage in the perforated piece a and the passage ³ in the
cock or plug, the position of which is adjusted by hand before the instrument is
immersed, and in which said position the measuring chamber is also in
communication by the passages in the perforated piece a with the air chamber b.
When the drawing up of the apparatus commences after the downward move-
ment is completed, the pressure of the water against an annular disc (which
surrounds the lower part of the apparatus) will effect a rotation of the cock or
plug into the position shown in Figs. 2 and 3, the disc or the ring & being con-
nected by a rod with a pin u² which is mounted eccentrically on one end of the
cock or plug. As may be seen from Fig. 2, the measuring tube / now passes out
of communication with the channel 2, so that its upper end is shut off, and then
into communication with the measuring chamber h. When the instrument is then
drawn up, the compressed air will expand gradually in the measuring chamber, and
drive a
corresponding amount of water out of the measuring tube through the
passage at its lower end, and when the instrument has been completely drawn up

page_text: the upper surface of the water column remaining in the measuring tube will indicate
on the scale i the depth of water to which the apparatus has been immersed. The
annular disc may also be replaced by two plates which can be turned down after
the rotation of the cock, in order that they shall not offer any resistance to the
water during drawing up.
is a projection on the side of the cock or plug k, which by striking against a
corresponding pin on the perforated piece u, indicates to what extent the cock
must be rotated by hand in order to render the apparatus ready for use. The pin n³.
then assumes the position shown by the line Z in Fig. 3.
Figs. 4 and 5 illustrate in vertical central section a second example of the con-
struction of the apparatus respectively during the immersion and during the drawing
up of the apparatus. The figures of reference in these two figures correspond with
those of Figs. 1-3.
The measuring chamber is in this case formed in the piece a. It is cylindrical
and is closed at bottom by the movable plunger y with its operating rod y². It
communicates at the top by means of the passage with the air chamber b, but
when there is no increase of pressure in the air chamber the communication is kept
closed by a cone valve y' and a spiral spring y' which surrounds the stem y' on the
valve piece.
When the apparatus is to be used the lower end of the operating rod y is pressed
from below until the plunger y' is thereby brought into the position shown in Fig. 4,
in which it is held by suitable projections which may also serve as guides for
the valve piece y'. The upper end of the measuring tube is then open through
the
passages sands in the piece a, and in the plunger y'; during the immersion
of the apparatus in the water the increasing pressure in the air chamber produced
by the immersion will open the cone valve y so that the air pressure in the air
chamber will be transmitted through the passages in the piece around the valve
rod y' down into the measuring chamber . Since the water pressure is transmitted
through the passage y³ in the piece u also to the underside of the plunger y', the
increasing pressure at its upper side will not move the plunger. As soon as the
apparatus has arrived at the desired depth and the drawing up of the same is then
begun, the decrease in the water pressure will have for result that the valve y' will
be closed by the spiral spring y' and that the plunger y will be pressed downwards
gradually into the position shown in Fig. 5 by the compressed air in the measuring
chamber during the expansion of the same. Whilst the plunger y is being pressed
down, the passages is then brought out of communication with the passage »³ so
that the upper end of the measuring tube is closed, and then the passage & comes
into communication with another passages in the plunger y, the latter passage
opening at top into the measuring chamber. The measuring chamber h comes
in consequence into communication with the measuring tube, which has for result
that the air in the same will expand during the further drawing up of the apparatus,
and will pass into the measuring tube, at the same time driving out a corresponding
amount of water out of the tube, as above described in connection with the apparatus
illustrated in Figs. 1 to 3. It should be understood however that the apparatus
shown in Figs. 4 and 5 is not suitable for measuring such small depths or differences
in depth as the apparatus shown in Figs. 1 to 3.
In order to restore to the air chamber the quantity of air withdrawn at each
measurement-namely, that which is taken up in a compressed state into the
measuring chamber-a cock or valve may be provided on the two forms of
apparatus described above to enable the air chamber to be placed for an instant in
communication with the atmosphere before the next measurement is made.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is :-
--
1. An instrument or apparatus for sounding or measuring the depth of water, in
which air is compressed during the sounding or measuring operation and in which

page_text: the measurement of the depth of water is effected by shutting or measuring off a
known or constant volume of the compressed air when the apparatus has reached
the depth it is desired to ascertain, the compressed air so cut or measured off being
admitted during or after the drawing up of the instrument or apparatus, to a
measuring tube provided with a suitable scale and in which the said known volume
of air is allowed to expand freely, and thereby indicate, according to Mariotte's
law, the depth to which the apparatus has been immersed, substantially as herein-
before described.
2. An instrument or apparatus for sounding or measuring the depth of water,
as specified in the preceding claim, constructed with a flexible air chamber 6 in
which the air is compressed by the water pressure during the immersion of the
instrument or apparatus, a measuring chamber h adapted to be placed in com-
munication with the chamber b, and in which a constant or known volume of the
compressed air can be shut off by suitable means from the chamber b, when the
apparatus has reached the point in the water whose distance from the surface of
the water it is desired to ascertain, and a measuring tube / with scale or the like,
the arrangement being such that the said measuring chamber h can be placed,
either simultaneously with said shutting off, or subsequently thereto, in communica-
tion with the measuring tube into which the compressed air in the chamber can
expand, and the expansion can be ascertained by means of the scale or the like, as
set forth.
3. The improved instruments or apparatus for sounding or measuring the depth
of water, constructed and operating substantially as hereinbefore described with
reference respectively to and shown in Figs. 1, 2 and 3; and in Figs. 4 and 5 of
the drawings annexed.
17
GEORG ADOLPH RUNG,
By L. W., per J. G. S.