IMPROVEMENTS IN ASTRONOMICAL INSTRUMENTS
Year: 1865

page_text: LETTERS PATENT to William Edward Newton, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Civil Engineer, för
the Invention of "IMPROVEMENTS IN ASTRONOMICAL INSTRUMENTS."―A
communication from abroad by George Davidson, of Philadelphia, in
the State of Pennsylvania, United States of America.
Sealed the 24th April 1866, and dated the 22nd December 1865.
PROVISIONAL SPECIFICATION left by the said William Edward Newton
at the Office of the Commissioners of Patents, with his Petition, on the
22nd December 1865.
I, WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Civil Engineer, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN ASTRONOMICAL INSTRUMENTS,"
to be as follows:-
Heretofore in ascertaining the altitude of any celestial or terrestrial object
by means of the sextant, quadrant, octant, reflecting circle, or their equivalents,
it has been necessary to have the sea horizon visible to the observer, or to use
the surface of a liquid or its equivalent as an artificial horizon, as is well

page_text: known; and on land it has been impossible to measure the depression or a
small angle of elevation of any object by means of the sextant, quadrant,
octant, reflecting circle, or their equivalents, with the artificial horizon; and it
has been almost impracticable to obtain by means of the same appliances the
altitude of objects having a greater angle of elevation than seventy degrees or
thereabout.
The present Invention enables the observer to measure the altitude or
depression of any object at sea either by day or by night when the sea horizon is
not visible, and on land the altitude or depression of any object may be
measured when the sea horizon is not. visible, or an artificial horizon not
procurable or available.
The Invention consists in attaching to the telescope holder or sight vane of
a sextant, quadrant, octant, reflecting circle, or their equivalents, a small spirit
level with a reflector and adjustable cross wire for determining the horizontal
plane, and with a segment of a double convex lens for transmitting the images
of the cross wire and bubble of the spirit level in a proper condition for
distinct vision, or of the equivalent of these means. This spirit level consists
of a tube closed at each end with plane glasses, the half of the tube nearer
the face-of-the-sextant or its equivalents being unoccupied from end to end.
to permit vision directly through to any object, and the other half of the tube
being occupied by a reflector having its reflecting surface towards the observer
and placed at a proper angle with the axis of the tube, and also with the half
or segment of a double convex lens secured in the inner tube, and capable of
adjustment for difference of vision. On top of the tube over an opening above
the reflector is secured a small spirit level in the direction of the tube, with an
adjustable frame immediately beneath the level, and carrying a fine wire at
right angles to the axis of the tube and parallel to the horizontal plane. The
images of the bubble of the spirit level and the cross wire are reflected by
the reflector through the double convex lens to the eye of the observer:
Instead of the reflector and double convex lens, other equivalent optical means
may be employed to effect the same purpose and to afford more light, such as
a prism and lens, or a prism with two convex surfaces; and instead of the
cross wire a cross line may be cut on the under side of the spirit level. The
level may be affixed to the sextant or its equivalents by having a tube about one
inch in length, with a milled head and screw collar to screw into the telescope
holder of the instrument, and then sliding the tube of the level into it. The
adjustment of this level or its equivalent is made by either changing the angle
of the reflector, or moving the frame carrying the cross wire, or by elevating
one end of the level itself, and consists in making the image of the cross wire

page_text: bisect the image of the bubble, when a distant object in the same horizontal
plane, and seen through the unoccupied half of the tube, appears on a level
with the image of the cross wire.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Edward Newton in the Great Seal-Patent Office on
the 22nd June 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of December, in the year of our
Lord One thousand eight hundred and sixty-five, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Edward Newton, Her special licence that I, the said William
Edward Newton, my executors, administrators, and assigns, or such others:
as I, the said William Edward Newton, 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 ASTRONOMICAL INSTRUMENTS," being a communication to'
me from abroad, upon the condition (amongst others) that I, the said William'
Edward Newton, 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 und immediately after the
date of the said Letters Patent. :
NOW KNOW YE, that I, the said William Edward Newton, do hereby
declare the nature of the said Invention, and in what manner the same is to
be performied, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say):―
.
Heretofore in ascertaining the altitude of any celestial or terrestrial object-
by means of the sextant, quadrant, octant, reflecting circle, or their equivalents,
it has been necessary to have the sea horizon visible to the observer; or to use-

page_text: the surface of a liquid or its equivalent as an artificial horizon, as is well
known; and on land it has been impossible to measure the depression or a
small angle of elevation of any object by means of the sextant, quadrant,
-octant, reflecting circle, or their equivalents, with the artificial horizon; and
it has been almost impracticable to obtain by means of the same appliances
the altitude of objects having a greater angle of elevation than seventy degrees
'or thereabout.
The present Invention enables the observer to measure the altitude or
depression of any object at sea either by day or by night when the sea horizon
is not visible, and on land the altitude or depression of any object may be
measured when the sea horizon is not visible or an artificial horizon not
procurable or available.
The improved instrument which forms the subject of the present Invention
is shewn in the accompanying Drawing, in which Fig. 1 represents a part
view of a sextant shewing a spirit level adapted thereto; Fig. 2 is an end
view of the spirit level; Fig. 3 is a longitudinal vertical section of the same.
The improvements consist in attaching to the telescope holder or sight vane of
a sextant, quadrant, octant, reflecting circle, or their equivalents, a small spirit
level with a reflector and adjustable cross wire for determining the horizontal
plane, and with a segment of a double convex lens for transmitting the images
of the cross wire and bubble of the spirit level in a proper condition for
distinct vision, or of the equivalent of these means. This spirit level consists
of a tube B, closed at each end, with plane glasses G, G, the half of the tube
nearer the face of the sextant or its equivalents being unoccupied from end to
end to permit vision directly through to any object, and the other half of the
tube being occupied by the reflector R, the reflecting surface of which is
towards the observer and is placed at a proper angle with the axis of the tube,
and also with the half or segment of a double convex lens L secured in the
inner tube T, capable of adjustment for difference of vision. On top of the
tube B, over an opening above the reflector R, is secured a small spirit level S
parallel with the tube, and provided with an adjustable frame F, immediately
beneath the level, and carrying a fine wire W at right angles to the axis of
the tube and parallel to the horizontal plane. The images of the bubble of
the spirit level and the cross wire are reflected by the reflector R through the
double convex lens L to the eye of the observer. Instead of the reflector and
double convex lens other equivalent optical means may be employed to effect
the same object and to afford more light, such as a prism and lens, or a
prism with two convex surfaces, and instead of the cross wire a cross line may
be cut on the under side of the spirit level. For observations on land, where

page_text: the instrument may be held with more steadiness than at sea, or sécured to a
fixed object, a small telescope, such as the weakest power usually furnished:
with the sextant, may be fitted to the eye end of the tube carrying the spirit
level. The level may be affixed to the sextant or its equivalent by having a
tube C about one inch in length with a milled head M, and screw collar to`
screw into the telescope holder H of the instrument, and then sliding the tube
of the level into it. The adjustment of this level or its equivalent is made
by either changing the angle of the reflector, or moving the frame carrying
the cross wire, or by elevating one end of the level itself, and consists in
making the image of the cross wire bisect the image of the bubble, when a
distant object in the same horizontal plane, and seen through the unoccupied
half of the tube, appears on a level with the image of the cross wire. This
adjustment can be readily effected on land, and may be made by means of the
level itself, and is not easily deranged. Should it become necessary to adjust
the level at sea the image of the cross wire when it bisects the image of the
bubble is made to appear on the same horizontal line with the visible horizon,
and then the correction for dip of the horizon is applied to all observed
altitudes and depressions with its proper sign. Observers with different
powers of vision should move the inner tube carrying the double convex lens
until the image of the cross wire appears sharp and well defined, when the
observer is looking through the tube at a distant object.
The operation in making an observation for the altitude or depression of an
object at sea or on land is as follows:-Secure the level in its proper place on
the instrument, hold the sextant or its equivalent in the usual manner with
the plane of its face in the vertical plane passing through the object and the
observer, and look through the tube of the level until the image of the bubble
is bisected by the image of the cross wire, move the vernier arm until the
image of the object is seen through the unoccupied half of the tube, and
bring the image of the object into the same horizontal line with the image
of the cross wire when bisecting the image of the bubble. If the sextant
or its equivalent and the level or its equivalent are in adjustment, the reading
on the arc indicated by the vernier is the observed altitude or depression of
the object. At night observations for altitude or depression of an object may
be made by illuminating the level by a lamp or by chemical means. The
index error may be determined when the level is adjusted on land and used
as a constant quantity for a not extended series of observations, or it may ba
determined at sea whenever the horizon is visible by observing the depression
of the horizon and taking the difference or sum of the observed result and the
computed dip for the index error.

page_text: Having now described the Invention which has been communicated to me
as aforesaid, I claim as the Invention secured to me by Letters Patent the
combination of the spirit level, cross wire, reflector, and double convex lens,
or their equivalents, with the sextant, quadrant, octant, reflecting circle, or
their equivalents, as and for the purpose above described.
In witness whereof, I, the said William Edward Newton, have hereunto
set my hand and seal, the Twenty-second day of June, in the year of
our Lord One thousand eight hundred and sixty-six.
Witness,
J. W. MOFFATT,
66, Chancery Lane.
W. E. NEWTON. (L.S.)