IMPROVEMENTS IN APPARATUS FOR ORTAINING LATITUDE AND LONGLE
Year: 1866

page_text: LETTERS PATENT to Cromwell Fleetwood Varley, of Fleetwood House,
Beckenham, in the County of Kent, for the Invention of "IMPROVEMENTS
IN APPARATUS FOR ORTAINING LATITUDE AND LONGLE
39
Sealed the 8th March 1867, and dated the 14th September 1866.
PROVISIONAL SPECIFICATION left by the said Cromwell Fleetwood Varley
at the Office of the Commissioners of Patents, with his Petition, on the
14th September 1866.
I, CROMWELL FLEETWOOD VARLEY, of Fleetwood House, Beckenham, in the
County of Kent, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN APPARATUS FOR OBTAINING LATITUDE AND LONGITUDE," to be
as follows:-
The Invention consists of a light lever carrying a wire, hair, or screen, called
the horizon line, the latter in the focus of the eye piece and object glass of a
small telescope, the lever is suspended by a thread or wire; the thread or wire
is kept uniformly tight by a spring or balance weight forming part of the lever
keeps it in the proper position; the weight is placed near to and below the
thread so that it may act like a very short pendulum and oscillate rapidly if set
in motion, in order that the slower motion of the ship shall not sensibly disturb
its true position. The fibre or support of the lever is placed in front of the
objeet glass, if one object glass is used, or between the two object glasses if a
double one be used, at such a distance (found by trial, that on elevating or

page_text: depressing the telescope above or below the horizontal line the image from
the object glass and the horizon line shall move an equal amount (at least
very nearly so). The moving lever is immersed in fluid, such as water, and
the object glass is constructed with such curves that it shall give a true image
after passing through the fluid, the whole space between the object glass and
eye piece being filled with the fluid. The object of the fluid is to cause the
borizon line to become rapidly stationary when it is set oscillating by the
movement of the observer. In some cases an aperture is made in the side
of the telescope to illuminate the horizon line when taking the altitude of
stars in a dark night. The illumination is effected by a small lamp attached
to or held near the instrument. The supports of the thread or wire are made
to rise and fall by a screw easily accessible to enable the operator to adjust
the horizon line to the natural horizon whenever necessary. The telescope
with its horizon line thus arranged is combined with other parts corresponding
with those of a reflecting sextant or quadrant, and the instrument is used in
a, similiar manner, the artificial horizon line replacing the natural horizon, the
horizon line does not necessarily obscure the natural horizon so that either
may be used.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Cromwell Fleetwood Varley, in the Great Seal Patent
Office on the 14th March 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CROMWELL
FLEETWOOD VARLEY, of Fleetwood House, Beckenham, in the County of Kent,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of September, in the year of our
Lord One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Cromwell Fleetwood Varley, Her special licence that I, the said
Cromwell Fleetwood Varley, my executors, administrators, and assigns, or
such others as I, the said Cromwell Fleetwood Varley, my executors,
administrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend, within
the United Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN APPARATUS FOR OBTAINING

page_text: LATITUDE AND LONGITUDE," upon the condition (amongst others) that I, the said
Cromwell Fleetwood Varley, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Cromwell Fleetwood Varley, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
This Invention has for its object improvements in apparatus for obtaining
latitude and longitude. For this purpose I employ a light lever carrying a
wire, hair, or screen, called the horizon line, the latter in the focus of the eye
piece and object glass of a small telescope; the lever is suspended by a thread
or wire, and a balance weight in connection with the lever keeps it in the
proper position; the weight is placed near to and below the thread, so that it
may act like a very short pendulum and oscillate rapidly if set in motion, in
order that the slower motion of a ship shall not sensibly disturb its true
position. The fibre or support of the lever is so placed that on elevating or
depressing the telescope above or below the horizontal line the image from
the object glass and the horizon line shall move an equal amount (at least
very nearly so). The moving lever is immersed in fluid such as water; the
object of the fluid is to cause the horizon line to become rapidly stationary
when it is set oscillating by 'the movement of the observer. In some cases an
aperture is made in the side of the telescope to illuminate the horizon line
when taking the altitude of stars in a dark night; the illumination is effected
by a small lamp attached to or held near the instrument. The supports of
the thread or wire are made to rise and fall by a screw easily accessible to
enable the operator to adjust the horizon line to the natural horizon whenever
necessary. The telescope with its horizon line thus arranged is combined with
other parts corresponding with those of a reflecting sextant or quadrant, and
the instrument is used in a similar manner, the artificial horizon line replacing
the natural horizon, the horizon line does not necessarily obscure the natural
horizon so that either may be used.
The plan which I prefer for carrying out this Invention in practice is
illustrated by the annexed Drawings.
Figure 1 is a longitudinal section, and Figure 2 a transverse section of the
instrument, the other Figures shew some of the parts separately.

page_text: Between the object glass A and the (positive) eye piece B of the telescope
a chamber is inserted whose two ends 9 are made of glass, and whose interior
is filled with pure water. A U-shaped spring s, Figures 1 and 2, stretches a
silk fibre and keeps it tight; this fibre passes through a light metal frame C,
and also through a piece of metal m, about of an inch long and of an inch
in diameter, to which also it is cemented. This piece of metal m forms the
pendulum and carries two heavy headed adjusting screws a and a¹ for adjusting
the position of the centre of gravity. A third screw 6 connects the light lever
which carries at its end the horizon line h (Figures 1 and 3), which also is a
silk fibre. The screw a is for adjusting the height of the horizon line h; the
screw a¹ is for rendering the horizon line horizontal. The pendulum is able
to swing either longitudinally or transversely of the instrument; this freedom
results from the way in which is hung by means of the square frame C already
referred to and shown in plan on an enlarged scale in Figure 4. The silk
fibre fpasses from the spring 8, down through the hole c, up through the
hole d, down through the hole d, and up through the hole c¹ to the other
extremity of the spring 8. The water effects two objects, the one that
of deadening the motion of the pendulum so that the rolling of the ship
does not set it sensibly swinging, the other that by its refracting power it
brings the centre of motion of the image within the telescope to coincide
with the centre of motion or support of the pendulum carrying the horizon h.
An adjustment may be provided to make this coincidence as accurate as
may be required, it is effected by the two prisms p and p¹, one or both
of which can be moved so as to increase or diminish the thickness of
glass through which the light has to pass, and by this means an effect
equivalent to the elongation or shortening of the water chamber is obtained;
or a double object glass may be used, and then by adjusting the distance
between them, and between them and the front glass g the motion of the
image and of h are made to coincide. The U-shaped spring carrying the
pendulum is mounted on a spring i, which is raised or lowered by means of
the milled head o, whose screw o¹ passes through a packing q to make it
water-tight; this screw is for adjusting the artificial horizon to the true horizon;
the cover is to prevent this screw from being disturbed by accident; the
telescope as thus constructed is attached to an ordinary sextant.
In this way
the artificial horizon is made to follow the real horizon, and thus when the
sun is visible but the true horizon is obscured, its altitude can by this instru-
ment be measured with sufficient accuracy for ordinary navigation. The torsion
of the fibre which supports the pendulum is not great, it is kept constant by the
springs, and is compensated for by trial. The projection w from the piece m,

page_text: and which enters the cup v, is to limit the motion of the pendulum so as to
prevent and h from being injured by rough usage. The tube x is for filling
the apparatus with water. I prefer to make the spring and pendulum of the
platinum silver alloy, supplied by Johnson & Matthey, as it does not oxidize.
To obtain pure water free from air for use in this instrument I put some
lumps of clear pure ice into a bottle.
This apparatus can be used for ascertaining the elevation above the horizon
of lights and other objects, and thus furnish the data for computing their
distance from the observer.
In witness whereof, I, the said Cromwell Fleetwood Varley, have hereunto
set my hand and seal, this Fourteenth day of March, in the year of our
Lord One thousand eight hundred and sixty-seven.
CROMWELL FLEETWOOD VARLEY. (L.S.)