IMPROVEMENTS IN REFLECTING INSTRUMENTS FOR TAKING CELESTIAL ALTITUDES
Year: 1877

page_text: LETTERS PATENT to Bernhard Türgen Friedrich Voss, Captain, in the City
of Hamburg, Germany, for the Invention of "IMPROVEMENTS IN REFLECTING
INSTRUMENTS FOR TAKING CELESTIAL ALTITUDES."
Sealed the 8th March 1878, and dated the 13th September 1877.
PROVISIONAL SPECIFICATION left by the said Bernhard Türgen Friedrich
Voss at the Office of the Commissioners of Patents on the 13th September
1877.
BERNHARD TÜRGEN FRIEDRICH Voss, Captain, in the City of Hamburg,
Germany. "IMPROVEMENTS IN REFLECTING INSTRUMENTS FOR TAKING CELESTIAL
ALTITUDES."
This Invention relates to improvements in reflecting instruments, and enables the
taking of altitudes with the same certainty and exactness as is usual but without
using the sea or visible horizon. Reflecting instruments furnished with this im-
provement can be used for observation in foggy or hazy weather, or in any case
where the horizon is obscured.
My Invention consists of the application of a sliding plate, partly covering the
horizon glass, and of a metal plate swinging in points or bearings between horizon
glass and telescope, and balanced and levelled by a weight. This plate is arranged
in such way as to allow the observer to see a ray of light of the height of the
apparent diameter of the sun between the level of the plate and the lower edge of
the horizon glass.
When an observation has to be taken the index glass is moved until the reflected
sun appears in the horizon glass within the space between the level of the plate and.
under the edge of the covering plate.
The end of the telescope I furnish with a cover having a very fine horizontal slit
with the level of the plate and a small central semicircular opening.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Bernhard Türgen Friedrich Voss in the Great Seal Patent Office on
the 13th March 1878.
BERNHARD TÜRGEN FRIEDRICH Voss, Captain, in the City of Hamburg,
Germany. IMPROVEMENTS IN REFLECTING INSTRUMENTS FOR TAKING CELESTIAL
ALTITUDES."
"
This Invention relates to improvements in reflecting instruments, and enables
the taking of altitudes with the same security and exactness as before without
using the sea or visible horizon. Reflecting instruments furnished with this improve-
ment can be used for observation in foggy or hazy weather, or in any case where
the horizon is obscured.
My Invention consists of a sliding plate, partly covering the horizon glass, and of
a metal plate swinging between points or in bearings between the horizon glass and
telescope, and balanced and levelled by a weight. This plate is so arranged as to
allow the observer to see a ray of light of the height of the apparent diameter of
the sun between level of plate and lower edge of the covering plate of the horizon
glass.
When an observation is to be taken the index glass is turned until the reflected
sun appears in the horizon glass within this space, between level of plate and lower
edge of covering plate.
The end of the telescope I furnish with a cover having a very fine horizontal slit
and a small semicircular opening.
In the accompanying Sheet of Drawings my Invention is fully explained as
applied to a reflecting instrument of ordinary construction.
Figure 1 represents a front view; Figure 2 a side elevation; and Figure 3 a
ground plan of the same; while Figures 4 and 5 show details and modifications of
my Invention.
A is the index glass; B, the horizon glass; and C, the telescope.
My Invention consists in the application of the following parts:-Swinging
between points r, r, or in bearings I attach to the instrument the metal plate D
furnished with a counterweight G for bringing the plate into horizontal position
during the taking of an observation; E is a plate applied for preventing unnecessary
rays of light from falling into the telescope; R is a cover for the end of the telescope,
which is furnished with a very fine horizontal slit and semicircular openings; 8 is
the covering plate adjustably attached to the horizon glass.
As will be seen from Figure 1 of the accompanying Sheet of Drawings the centre
line or line of sight x, x, of the telescope is just above the surface of plate D when
the instrument is kept in horizontal position. By shifting this position to either
Bide the plate will directly alter its position to line x, x, and will either rise to the
left above the lower edge of the covering plate, or to the right above the slit of the
cover R of the telescope. For this reason the instrument will only allow of taking
an observation when kept in a horizontal position.
In bringing the reflected sun between the level of the plate and the lower edge of
the covering plate by turning the index glass A correspondingly, while the instru-
ment is kept in horizontal position, the proper height of the sun is indicated upon
limb H.
Figures 4 and 5 show a modification of the construction of plate D. The counter-
weight G is furnished with adjusting screws for securing an exact balance of the
plate in horizontal position. On the top of the plate a weight G¹ is attached for
reducing the vibration of the plate and for making the same steadier and the instru-
ment better applicable in rough weather.
Instead of a telescope with cover and slit, as shown in the annexed Sheet of
Drawings, I sometimes use an occular dioptra furnished with a very fine centre
boring only.

page_text: And having now described the nature of my said Invention and in what manner
the same is to be performed, I declare that what I claim as my Invention and wish
to secure by Letters Patent is,-
First. The application of a plate swinging between points or in bearings furnished
with a counterweight, and arranged between the horizon glass and the end of a
telescope or dioptra of reflecting instruments for the purpose and in the manner as
described, and substantially as shown in the Drawings.
Secondly. The modifications of my Invention in the manner described, and as
shown in Figures 4 and 5 of the annexed Drawings for the purpose set forth.
In witness whereof, I, the said Bernhard Türgen Friedrich Voss, have here-
unto set my hand and seal, this Twenty-sixth day of February, One
thousand eight hundred and seventy-eight.
BERNHARD TÜRGEN FRIEDRICH VOSS. (L.S.)