FACILITATING THE CALCULATIONS OF NAVIGATION TO BE CALLED OR KNOWN AS "THE NAVIGARIUM
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
We JESSE SILVERSIDES, 62 Duke Street, New Clee, Grimsby Teacher of
Mathematics WILLIAM DUDDING, Master Mariner, Newport Brough Yorkshire
& HENRY MEGSON of Newport in the East Riding of the County of York,
Schoolmaster do hereby declare the nature of the said Jesse Silverside's
invention for FACILITATING THE CALCULATIONS OF NAVIGATION TO BE CALLED OR
KNOWN AS "THE NAVIGARIUM" to be as follows:-
This instrument consists of an oblong plate whereon is engraved a quadrant
divided into degrees & also into 8 points & their subdivisions corresponding to
those of a compass.
To the centre of this, after the manner of a jointed rule, are fixed two arms:-
one in a horizontal position, & the other as a movable radius which may be set at
any given angle. Overlying these is a moveable perpendicular with a cross peice
at the bottom & a guide beneath working in a groove & retaining it in a upright
position. On these pieces are two scales the one divided into tenths & the other
into sixths of their respective units. The object of these arrangements is the
working of nautical problems by geometrical construction by which the problems
of navigation may be solved with accuracy, & facility exceeding that of ordinary
methods.
JESSE SILVERSIDES,
WILLIAM DUDDING.
HENRY MEGSON,

page_text: COMPLETE SPECIFICATION.
JESSE SILVERSIDES, Teacher of Mathematics 62 Duke Street, New Clee,
Grimsby, WILLIAM DUDDING Master Mariner Newport Brough Yorkshire HENRY
MEGSON, Schoolmaster, Board School, Newport Brough East Yorkshire, do hereby
declare the nature of our invention for FACILITATING THE CALCULATIONS OF
NAVIGATION, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This Instrument consists of an oblong plate, on which is a quadrantal arc divided
into degrees and also into points and quarter points, corresponding to those of a
compass card-To the centre of this arc is fixed a Radius attached jointlike to a
Horizontal Bar Overlying these is a Perpendicular rising from a cross-piece per-
forated so as to shew the scales beneath-From the cross-piece descends a rectangular
arın in a line with the Perpendicular, and stretching over the sliding Mercator
scale Under the cross-piece is fixed a guide working in a groove, and retaining
the Perpendicular in an upright position-On the Radius, the Perpendicular, and
the Horizontal Bar-are two scales, one representing degrees and their subdivisions
into ten-minutes each; the other a decimal scale, shewing the number of nautical
miles in any number of degrees and parts thereof within the limits of the
degree scale-To each scale also is attached a vernier reading to tenths of
the subdivisions.
By moving the Perpendicular and the Radius into positions indicated by the
data of a problem, a Triangle is determined between the intercepted edges of these
and the Horizontal bar, wherein the required results are represented in position and
magnitude; which by means of the verniers are read off with reliable accuracy.
The sliding Mercator scale consists of several sections whose length is determined
by the breadth of the plate-Of these sections there may be any number according
to the range of latitude required-Any section may be used in place of another, or in
conjunction with a consecutive piece-This scale is throughout its length divided
by ten parallels crossed by diagonals, by which the subdivisions of the scale,
though varying in length according to latitude, are all decimally divided-This
provides the means of accurately setting off the "Meridional difference of Latitude,"
thus: The lower latitude being set at the zero point of the bar above, the
Perpendicular is to be placed so that the edge of the lower arm cuts the upper
latitude; then. the intercept between the zero point and the arm, is the "Meridional
Difference of Latitude" - If now the index on the Perpendicular be set for the
"Difference of Longitude," and the radius rotated till it meets the Perpendicular
at this point, the "Bearing" will be indicated on the arc with considerable
exactness.
At the top of the plate is a scale shewing the relation between Time and
Longitude-It consists of several sections, interchangeable.
At the upper right hand corner is a Course Corrector, consisting of compass card
and index turning on independent axes, so that either may be rotated without
disturbing the other-This is for correcting the true course for variation in
reference to steering, and the compass course for leeway and variation, in order
to correct reckoning.

page_text: And in order that our invention may be more completely understood reference
is given to drawings being those filed with the Provisional Specification.
DERSTAN A
DOMINA
And in order that our invention may be more completely understood reference
is given to drawings being those filed with the Provisional Specification.
DESCRIPTION OF DRAWING
A. B. C. D is an oblong plate.
QPa quadrantal arc divided into degrees and also into points and quarter
points.
R is a movable radius working from the centre C. and attached to H, a horizontal
bar. Pra movable perpendicular rising from cross-piece Cr, perforated so as to
shew the scales beneath-N a rectangular arm descending from cross-piece.
Ma Mercator Scale sliding between bars S S¹-It is divided longitudinally by
ten parallels, crossed by diagonals subdividing the smaller divisions of the scale into
ten equal parts-It is for determining bearings.
On the perpendicular, radius, and horizontal bar, are two scales, one being a scale
of degrees subdivided into six parts of ten minutes each-The other a decimal scale
shewing the number of nautical miles in any given extent on the degree scale.
V. Vi Vare Verniers attached respectively to the scales and arc.
A. B. is a scale shewing the relation between Time and Longitude.
W represents a Course Corrector consisting of compass card and index turning
on independent axes-It is for correcting true course for variation with reference
to steering and compass course for leeway and variation in order to correct
reckoning.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed-what we claim is
The apparatus by means of which together with the scales designed for the
purpose, a right angled Triangle may with expedition be constructed applicable to
those problems of Navigation known as Dead Reckoning; including Parallel
Sailing, Plane Sailing Middle Latitude Sailing, Traverse Sailing, and Mercator
Sailing This, together with the scale of Time and Longitude and the Course
Corrector as accessories, so completely supersedes the ordinary modes of calculation
as to make the work little more than the registering of data, and the results
derived from them by means of this instrument.