Improvements in Appliances for Determining a True Horizon in connection with Sextants and like Instruments.
Year: 1899

page_text: Date of Application, 2nd Sept., 1899
Complete Specification Left, 5th June, 1900-Accepted, 14th July, 1900
Improvements in Appliances for Determining a True Horizon in
connection with Sextants and like Instruments.
I, LOUIS WHIDBORNE, of 113, Kingsley Road, Liverpool, in the County of
Lancaster, Master Mariner, do hereby declare the nature of this invention to be.
as follows:-
It is often the case particularly at sea, that the sun or other heavenly bodies
may be seen whilst the horizon is obscured by haze or fog and many opportunities
of taking observations are lost because a horizon cannot be found.
The object of this invention is to provide an appliance for attachment to
sextants or like instruments by means of which such instruments may be readily
and certainly adjusted to a true horizon and easily maintained in that position
whilst an observation is being taken notwithstanding the actual horizon being
obscured; such appliance being simple in construction and attachment and
reliable in operation.
For these purposes I make use of a box, tube, or frame, to which is freely
suspended by pivots, knife edges or otherwise a frame or piece carrying one or
more wires. The frame is weighted or balanced so that the wires are always kept
level or horizontal. A fixed wire is also provided in the box to act as the horizon
but this may be dispensed with in some cases, one of the wires on the suspended
frame acting as the horizon. The box also carries a spirit level or like "device
arranged preferably at right angles to the swing of the frame carrying the wires.
The box is attached to a sextant or other instrument in any convenient manner
and so that the wires and spirit level can be observed through the usual eye piece
attached to the instrument. By this means when the wires are brought into line
with the eye piece or a fixed point on the instrument, and the bubble in the spirit
level is in the centre the instrument is adjusted for the true horizon in all
directions.
£ Contos 1900
Improvements in Appliances for Determining a True Horizon in
connection with Sextants and like Instruments.
I, LOULS WHIDBORNE, of 113, Kingsley Road, Liverpool, in the County of
Lancaster, Master Mariner, do hereby declare the nature of this invention and in
what manner the same is to he performed, to be particularly described and

page_text: ascertained in and by the following statement, reference being had to the accon
panying drawings and to the figures and letters marked thereon:-
It is often the case, particularly at sea that the sun or other heavenly bodies
may be seen whilst the horizon is obscured by haze, fog, or other cause and many
opportunities of taking observations are lost because a horizon cannot, be found.
Many attempts have been made to obtain an artificial horizon for use with
sextants but hitherto the appliances devised have been uncertain in action and
unreliable.
The object of this invention is to provide an appliance for attachment to
sextants or like instruments by means of which such instruments may be readily
and certainly adjusted to a true horizon and easily maintained in that position
whilst an observation is being taken notwithstanding the actual horizon being
obscured, such appliance being simple in construction and attachment and
reliable in operation.
On the drawings Fig. 1 is a longitudinal section of appliances constructed
according to my invention. Fig. 2 is a cross section of the same and Fig. 3 is
a plan. Fig. 4 is a view showing the appliances attached in position on a
sextant. For the purposes above mentioned, I make use of a box, tube, or
frame, to which is freely suspended by pivots or knife edges b, or the like, à
frame consisting of two side pieces c connected together by a bar c. The frame c,
carries wires d, d, stretched transversely between the side pieces at each end.
a', is a sliding cover to the box. The frame is weighted or balanced so that the
wires are always kept level or horizontal in the direction of the length of the
appliance. The weighting or balancing is conveniently done by making the
bur c', of sufficient mass or weight for the purpose as shown. e, is a wire fixed
to the sides of the box a, to act as the horizon when only one wire d, is used on
the suspended frame c, but when, as shown, two wires are used on the frame c,
the fixed wire e, may be dispensed with as the wire d' will act as the horizon.
f is a spirit level carried in the box u, and preferably at right angles to the swing
of the trame c, carrying the wires d, d¹. The box a, is attached to the sextant
in the line of sight between the eye piece and the horizon glass in any convenient
way but preferably by passing the short screwed tube a³, through the eye piece
ring, g, on the sextant, and then screwing the eyepiece tube h, on to such tube a³,
as shown., is a glass in the end of the box a. The line of sight passes from
the orifice j, in the usual eyepiece past the wires d, d', to the usual line on the
horizon glass k, the spirit level being also observable at the same time; and when
the instrument is moved so that the wires d, d', are brought into line with the
orifice in the eyepiece, or with other desired fixed point on the instrument, and
the bubble in the spirit level is in the centre, the instrument is adjusted for
the true horizon in all directions and by moving the limb m, of the sextant, the
image of the sun or other object can be brought down to a true horizon and the
angle observed in the usual manner, with the advantage however that no correc-
tion has to be made for dip, or the height of the observers eye above the water.
The instrument may be used in any sheltered position providing the sun or other
object which it is desired to observe is visible from such position; the wires d, d¹,
in conjunction with the spirit level f enabling the instrument to be held exactly
vertical.
I do not confine myself to the exact construction of the parts as shown as it
will be obvious various modifications may be made without departing from the
essential features of the invention but,
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
First. The combination with a sextant or like instrument of a weighted or
balanced frame suspended to pivots or knife edges or equivalent devices and carry-

page_text: ing one or more transverse wires; and a spirit level or like device arranged
transversely to the suspended frame substantially as and for the purpose get
forth.
Second. The combination with a sextant or like instrument of a weighted or
balanced frame carrying a transverse wire and suspended to pivots or knife edges
or equivalent devices; a fixed transverse wire, and a spirit level or like device
arranged transversely to the suspended frame substantially as and for the purpose
set forth.
Third. The combination with a box or frame having a sight opening at each
end and being provided with pivots or knife edges of a weighted or balanced frame
carrying one or more transverse wires and suspended to such pivots or knife edges
and a spirit level or like device all arranged and operating substantially as and
for the purpose set forth.
Dated this First day of Tune 1000