AN INSTRUMENT FOR ASCERTAINING THE DEPTH OF WATER IN SEAS AND RIVERS
Year: 1835

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Jonn
ERICSSON, of Albany Street, Regent's Park, in the County of Middlesex, Civil
Engineer, send greeting.
WHEREAS His present most Excellent Majesty King William the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Fourteenth day of November, in the sixth year of His
reign, did, for Himself, His heirs and successors, give and grant unto me,
the said John Ericsson, His especial licence, full power, sole privilege and
authority, that I, the said John Ericsson, my exors, adiñiors, and assigns, or
such others as I, the said John Ericsson, my exors, adñiors, or assigns,
should at any time agree with, and no others, from time to time and at all
times during the term of years therein expressed, should and lawfully might
make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, my Invention of "AN INSTRUMENT FOR ASCERTAINING
THE DEPTH OF WATER IN SEAS AND RIVERS;" in which said Letters Patent is
contained a proviso, that I, the said John Ericsson, shall cause a particular
description of the nature of my said Invention, and in what manner the
same is to be performed, to be inrolled in His said Majesty's High Court
of Chancery within six calendar months next and immediately after the date
of the said in part recited Letters Patent, as in and by the same, referenco
being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
John Ericsson, do hereby declare the nature of my said Invention, which I
call a sounding instrument, to consist in an arrangement of tubes and an air
chamber, within which I cause the pressure of the water, the depth of which
is to be ascertained, to compress a quantity of atmosphere air till its expansive
force shall be exactly equal to the external pressure of the said water upon the
instrument, at whatever depth it may be, at the same time that the degree of
compression thus obtained is indicated by the height of a column of the said
water which the said pressure causes to overflow into a graduated tube or
recipient arranged to receive it, and by which the depth sought will be accu-
rately ascertained, and may be read off independently of any measurement
upon the line to which the instrument is attached. And in further com-
pliance with the said proviso, I, the said John Ericsson, do hereby describe
the manner in which my said Invention is to be performed, by the following
statement thereof, [reference being had to the Drawing annexed (which is
made to a scale of six inches to a foot), and to the figures and letters marked
thereon (that is to say) ->
DESCRIPTION OF THE DRAWING.
Figure 1 is a vertical section of one of my said sounding instruments. A is
a stem of cast metal, with a cavity to receive the strong glass tube B; this tube
is open at each end, and is cemented firmly into the cavity cast in the stem to
receive it; C is the tap of the stem, having a passage through the centre, into
which is screwed the hollow tap D, which holds the small tortuous copper
pipe E; this tortuous pipe is also open at both ends, and thus leaves a free
passage into the glass tube below it; F, F, G, is a cast metal hollow cap,
fitted by a screw F, F, air-tight on the stem A, and having an eye at G, by
which it is attached to what is usually called the lead line. It will be
observed that the tortuous pipe E reaches nearly to the top of the air
chamber H, formed by the cap F, F, G, and there must be a small passage
bored through the top of the stem from I to J, in order that the external air
or water, as the case may be, may have a free passage into the chamber H. On
to the bottom of the stem is screwed the piece K, having an open channel
L, L, communicating with the glass tube B, and furnished with a stop-cock M
for the purpose of emptying the tube when required; N is a cavity cast in the
piece K to receive what is usually called the arming or grease, to ascertain the
nature of the bottom when sounding; O is a graduated scale, from which the
depth may be read off after each operation of the instrument. This scale is
so graduated as to indicate the depth in fathoms, and the mode of graduating

page_text: it which I have adopted is as follows:-I place the instrument in a closed
vessel of water, and submit the water to pressure by means of a force pump,
as shown at Figure 4; a mercurial guage T is attached to the water vessel,
and at every five inches and forty-three hundredths that the mercury rises, I
remove the instrument from the water vessel, and mark the height at which
the water which has overflowed stands in the glass tube or recipient, and each
mark so made will indicato one additional fathom. Figure 2 is a transverse
section of the instrument taken on the line P, Q; and Figure 3 is a side view
of the instrument. The operation of my said sounding instrument will be as
follows: When dropped overboard (the stop-cock M being shut), the water
from the sea or other external water will enter the chamber H through the
open passage I, J, driving the atmospheric air (which the chamber of course
contains) before it through the tortuous pipe E into the glass tube B, and
when the chamber H becomes quite filled the water will then overflow into
the tortuous pipe E, and fall into the recipient or glass tube B, where it will
continue to rise as the instrument descends, compressing the air in the tubo
until it becomes of an expansive force equal exactly to the pressure of the
surrounding sea or other external water, at which point the overflowing will
cease of course. When the instrument is lifted up, the water in the glass
tube will remain at the height it attained when the instrument was at its
greatest depth in the sea; but the air contained in the tube will, in proportion
as the instrument ascends and the external pressure diminishes, expand into
the chamber H, driving out the water through the passage I, J, so that by
the time the instrument is hauled on board this chamber will be entirely freed
from water, and the level or top of the column of water in the glass tube will
show on the graduated plate O the depth, as before described. When this
depth has been read off, by giving one quarter of a turn to the stop-cock M,
the water will run out of the glass tube, and by shutting it again the instrument
becomes ready for a second operation.
Now, whereas I claim as my Invention the instrument herein-before de-
scribed, by dropping which into the water the depth of which is to be ascer-
tained, I cause within the said instrument an overflow of non-elastic fluid, and
a compression of air or other elastic medium, such overflow and compression
being effected by the external pressure of the said water, aud in such manner
that the expansive force of the said compressed air or other medium shall at
all times be equal to the said external pressure of the said water, while the
height or level of the fluid which has overflowed shall at all times indicate,
by means of the scale attached to its recipient, the extreme depth in fathoms
lo which the instrument has descended. And such my Invention being to the

page_text: best of my knowledge and belief entirely new, and never before used within
that part of His said Majesty's United Kingdom of Great Britain and Ireland
called England, His said Dominion of Wales, or Town of Berwick-upon-
Tweed, I do hereby declare this to be my Specification of the same, and that
I do verily believe this my said Specification doth comply in all respects fully
and without reservo or disguise with the proviso in the said herein-before in
part recited Letters Patent contained; wherefore I do hereby claim to
maintain exclusive right and privilege to my said Invention.
In witness whereof, I, the said John Ericsson, have hereunto set my
hand and seal, this Fourteenth day of May, in the year of our Lord
One thousand eight hundred and thirty-six.
JOHN (L.s.) ERICSSON.
Inrolled the Fourteenth day of May, in the year of our Lord One
thousand eight hundred and thirty-six.