Improvements in Apparatus applicable for Measuring on Board Ship the Distance of same from Shore
Year: 1899

page_text: Date of Application, 19th June, 1899-Accepted, 21st Oct., 1899
Improvements in Apparatus applicable for Measuring on Board Ship
the Distance of same from Shore,
We, NILS AALL KRAG, Merchant, of 16, Raadhnsgade, Christania, and OLAF
ARNESEN, Engineer, of Bækkelaget, near Christiania, in the Kingdom of Norway,
do hereby declare the nature of this invention and in what manner the same is
to. be performed, to be particularly described and ascertained in and by the
following statement:-
The improvements in apparatus applicable for measuring on board ship the
distance of same from shore have for object to provide a convenient means for
graphically, ascertaining how far the ship is from a point on shore, before the
point has been passed, and how far the ship will be from the point when the
ship comes abreast of it while a certain course is held. With the usual apparatus
such measurements have only been possible by the aid of charts, so that the
captain had first to take observations on deck and then to go into the cabin
for making calculations by the aid of compasses and charts.. Furthermore it
was necessary to know the point on which bearings were taken in order to carry
out the calculations.
Now by means of our apparatus when a certain point on shore is in sight, which-
ever it be and whether that point is known or not, it becomes possible by taking
bearings on it twice and by noting on the log the distance run meanwhile to
read off on the instrument at once, how far the ship was from the point when
the respective bearings were taken, and also to ascertain graphically, how far
the ship will be off the said point when it shall have arrived directly abreast of
it, and that without the use of books, charts, tables or other apparatus.
The apparatus consists of the following principal parts viz., an arc piece,
generally a quadrant of a circle (or half circle or whole circle) graduated:'in
accordance with the compass, two graduated radius bars that can turn on the
centre of the arc, and a graduated straight edge on a cross bar that can be moved
parallel with the base or zero line of the quadrant.
Fig. 1 of the accompanying drawings is a diagram for illustrating the manner
of using the apparatus, Fig. 2 is a plan view of the apparatus in quadrant form,
and Fig. 3 a perspective plan of an apparatus in half circle form.
G Fig. 2 is a quadrant having its are divided in compass division lines and
degrees. A and B are two radius bars that can turn on the centre of the arc
and are along the edges towards each other provided with divisions (for meter
measure as in the example here shewn, or for yards cable lengths and miles or
other measure as desired). These radius bars can be fixed in position by small
clamping screws E. D is a graduated straight edge which is movable in its
length direction on another bar H that at the right hand end is formed with a
head K that grasps and can slide up and down upon a bar G₁ at right angles
to the zero radius or base line of the instrument. This bar H can be moved
up and down by hand, or by means of tooth rack I and pinion L provided with
a hand wheel M. By means of the sliding straight edge D we greatly facilitate
the operation and obviate all calculation. If the straight edge D were not pro-

page_text: vided, and if the division lines were on the bar H instead, there would have
to be made subtractions at each operation, which is inconvenient and tedious.
The movement of the straight edge on the bar H may be effected direct by the
hand or as shewn by means of a. toothrack O, pinion P and hand wheel R.
The apparatus is used in the following manner. Let o Fig. 1 be a point on
the coast which the ship has to pass, then a bearing is first taken thereon when
the ship is say at 1, and the radius bar A is placed say against the point 3 on
the arc; some time after a bearing is taken when the ship is say at 2 with the
radius bar B which is placed say against
on the arc. If the distance mean-
while run be say 5 miles, the bar H is moved so far that the radius bars A and B
cut a piece equal to 5 off the straight-edge ]). Then it is at once ascertained by
reading off on the radius bars that the ship at the first bearing taking was
8 miles off the point o and at the second bearing taking 5 miles off the point o.
If it now be further desired to ascertain how far the ship will be off the point o
when it is directly abreast of it, the radius bar B is swung into the dotted or
upright position Fig. 2; the straight edge D is moved to the right that is to
say up to the new dotted position of the radius bar B, and the distance, viz.
4 miles is read off. That these readings are correct will be easily perceived,
as the triangle 1, 2, o, Fig. 1 will always be congruent with the triangle cut off
between the rádius bars A and B, and the lower edge of the straight edge D.
Fig. 3 shews a half circular apparatus which can be used for either side of
the ship. It is of the same construction as that in Fig. 2, except that the tooth
wheel gearings are omitted, and that sights or diopters C are provided on the
radius bars. But these are not required, if the instrument is used over the com-
pass, as intended with Fig. 2.
The cross bar H slides with a block H' in the guide slot Q.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed, we declare that what
we claim is;
--
1. A distance measuring apparatus consisting of an arc piece graduated in
accordance with the compass and fitted with two graduated radius bars capable
of being moved in a quadrant of the arc, and fitted with a transverse bar cap-
able of being moved parallel with the base or zero radius of the arc piece said
bar being provided with a graduated straight edge adapted to slide along it,
substantially as and for the purpose set forth.
2. A distance measuring apparatus as firstly claimed provided, with tooth
wheel gearing for moving the transverse bar up and down and with tooth wheel
gearing for moving the straight edge along it, substantially as set forth.
3. The constructions of apparatus shewn on the drawings.
Dated this Nineteenth day of June 1859.
centn
June 1930,
JENSEN & SON,
77, Chancery Lane, London W.C., Patent Agents.