An Instrument for Comparing the Time of Day at Different Places on the Earth.
Year: 1888

page_text: Date of Application, 14th June, 1888
Complete Specification Left, 6th Dec., 1888
Complete Specification Accepted, &th Jan., 1889
PROVISIONAL SPECIFICATION.
An Instrument for Comparing the Time of Day at Different
Places on the Earth.
I, ALEXANDER KELT, of 122 Murraygate Dundee, County of Forfar, Watchmaker
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to provide a ready means of comparing the time of
day at any part of the earth, (the poles excepted) with the time of day at any other
part of the earth (the poles excepted), at the same instant.
Thus, the Geochronoscope, by a simple operation, may be made to show what time
of day it is at New York, Pekin, or any other town, when it is 12 o'clock, or any
other given time, at Greenwich, Vienna, or any other town. It also shows the meridian
which is opposite to any given meridian.
The Geochronoscope consists of a cylinder which can be rotated on its axis, and
standing upon a base bearing the pivot, on which it is rotated.
Round this cylinder is fixed a map or chart of the world, showing Latitudes, Longi-
tudes, and the Geographic situation of the different towns, cities, countries, and other
places on the earth.
On the top of this cylinder, and firmly attached thereto, is an hour circle. The
cylinder and hour circle may be made in one piece. This hour circle has its whole
circumference divided into twenty-four equal parts, which parts are figured, from right
to left, or from east to west, consecutively from. 1 to 24, or from 1 to 12 twice
repeated, or both, to represent the twenty-four hours of a day.
On the top of this first hour circle, is another hour circle, which is capable of being
rotated independently of the cylinder and first hour circle, and having its circum-
ference also divided into twenty-four equal parts, but figured from left to right, or from
West to East, from 1 to 12 twice repeated and representing the hours of a day.
This upper hour circle is also divided into degrees of Longitude.
A rod, or wire, or a frame whose sides are parallel to the axis of the cylinder, is
used as an external meridian, and also furnishes the top support of the cylinder and
hour circles.

page_text: On the sides of the frame are marked degrees of latitude corresponding to those on
the map.
The whole instrument, with all its parts, may be made of wood, paper, metal, or any
suitable materials.
The instrument is used in the following manner.
If it is desired to know the hour of the day at a stated town, the time at any other
town being given, the cylinder is rotated on its axis until the place whose time is
known comes directly under the external meridian. The upper hour circle is then
rotated, until the given time on it is also brought under the meridian. The cylinder
is again rotated, and carries the upper hour circle with it, until the place whose time
is wanted comes under the external meridian, then under the meridian, and on the
upper hour circle, will be found the time of day at the place in question.
Dated this Twelfth day of June 1888.

page_text: COMPLETE SPECIFICATION.
An Instrument for Comparing the Time of Day at Different
Places on the Earth.
I, ALEXANDER KELT, of 122 Murraygate, Dundee, in the County of Forfar,
Watchmaker, 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 object of this invention is to provide a ready means of comparing the time of
day at any part of the earth (the poles excepted) with the time of day, at the same
instant, at any other part of the earth (the poles excepted).
Thus, the instrument, by a simple operation, may be made to show what time of day
it is at New York, Pekin, or any other town, when it is twelve o'clock, or any other
given time at Greenwich, Vienna, or any other town. It also shows the meridian
which is opposite to any given meridian.
The instrument consists of a cylinder which can be rotated on its axis, and standing
upon a base bearing the pivot on which it is rotated. Round this cylinder is fixed a
map or chart of the world showing latitudes, longitudes, and the geographic situation
of the different towns, cities, countries, and other places on the earth. On the top of
this cylinder, and firmly attached thereto, is an hour circle. The cylinder and hour
circle may be made in one piece. This hour circle has its whole circumference divided
into twenty-four equal parts; which parts are figured, from right to left, or from East
to West, consecutively from one to twenty-four, or from one to twelve twice repeated,
or both, to represent the twenty-four hours of a day.
On the top of this first hour circle is another hour circle, which is capable of being
rotated independently of the cylinder and first hour circle, and having its circum-
ference also divided into twenty-four equal parts, but figured from left to right, or
from West to East, from one to twelve twice repeated and representing the hours
of a day. This upper hour circle is also divided into degrees of longitude.
A rod, or wire or a frame whose sides are parallel to the axis of the cylinder,
is used as an external meridian, and also furnishes the top support of the cylinder
and hour circles. On the sides of the frame are marked degrees of latitude corre-
sponding to those on the map. The whole instrument, with all its parts, may be made
of wood, paper, metal, or any suitable material.
The instrument is used in the following manner :-If it is desired to know the
hour of the day at a stated town, the time at any other town being given, the cylinder
is rotated on its axis until the place whose time is known, comes directly under
the external meridian. The upper hour circle is then rotated until the given time on
it, is also brought directly under the meridian.
The cylinder is again rotated (and carries the upper hour circle with it) until the
place whose time is wanted comes under the external meridian, then under the
meridian, and on the upper hour circle will be found the time of day at the place in
question.

page_text: DESCRIPTION OF DRAWINGS.
In these drawings the same reference letters and numerals are used to mark the
same or like parts, wherever they are repeated.
Figs. 1. and 2. (Sheet No. 1.) represent an elevation and plan respectively, of the
instrument for comparing the time of day at different places on the earth.
Fig. 3. (Sheet No. 2.) represents the surface of the cylinder and the loose upper
hour circle, laid out flat upon a plane.
c. is the cylinder having a map or chart m. of the world fixed round it, showing the
usual degrees of latitude and longitude. The cylinder rotates upon its axis ;-h. w.
being the hand wheel for turning it-t.j. being the top and b. j. the bottom journals
respectively.
The cylinder is carried by a frame consisting of a base b, two upright rods r. r. and
a cross-beam c. b.
The rods r. r. are marked as shewn with degrees of latitude, corresponding to those
on the map. The opposite sides of these rods are also marked in a similar manner.
H. C. and h. c. are the hour circles on the cylinder; H. C. showing the time divided
into two periods of twelve hours each, in which twelve o'clock noon, coincides with
the Greenwich meridian, and h. c. showing the time divided into twenty-four parts, in
which twelve o'clock noon also coincides with the Greenwich meridian.
H, C, is the hour circle upon tho upper cylinder u. c.-which can be rotated inde-
pendently of the other cylinder c.-and is divided into two periods of twelve hours; the
hours being numbered in the opposite direction to those on cylinder c., twelve noon
being on the same longitudinal line as the 360° or 0° as shown, while twelve midnight
is under the 180°.
The top of this hour circle is divided into degrees; the top series t. s. of which,
goes from 0° to 360° to the right hand, the lower series 7. s. from 0° to 360° to the
left hand as shewn. From twelve midnight to twelve noon-on this upper hour circle
-is shewn by the clear portion A.M., and from twelve noon to twelve midnight by
the shaded portion P.M., so that morning or evening may be readily known at any
part of the world when using the instrument.
On one side of the instrument is a projecting arm a. which carries by preference a
black piece of stretched elastic cord e. c., the other end of which is fixed to a hook h.
inserted in the base b. This elastic cord is used as an outside meridian, while directly
opposite is a rod or wire w. for indicating the opposite outside meridian. I may use
the upright rods r. r. for this purpose but prefer the aforesaid elastic cord e. c., and
vertical rod w.
I will now briefly show how the instrument may be used :-
To find the time of day at any part of the world. Bring the part of the world where
the instrument is located under the external meridian or elastic cord e. c.
The upper
or loose hour circle u. c. is then set until the correct time (say Greenwich time) is also
below the elastic.
The whole cylinder carrying the upper hour circle with it, is then rotated by means
of handwheel h. w. until the place where the time is wanted is brought under the
elastic cord.
Then on the upper hour circle will be found the time of day, or night of the place
wanted.
For example: Suppose the time at New York N.Y. (Sheet No. 2.) to be five
o'clock A.M. and it is required to find the time at Pekin P. Set the upper hour circle
until N.Y. and five o'clock A.M. are under the elastic cord. Rotate the cylinder_and
upper hour circle together until P. is under the elastic cord. Then on the upper hour
circle it will be seen that the time is 5-45 P.M. By turning the cylinder and with
it the upper hour circle so that any other place comes under the elastic cord and
looking at the time on the upper hour circle, gives the time of that place. Thus when
time is five o'clock A.M. at New York, at London it is ten o'clock A.M., at Vienna
11. A.M., at Mecca 12-30 P.M., Calcutta 3-45 P.M. and Sydney 8. P.M. Although

page_text: the primary idea of this instrument, is to find out the time of day at any place on
the Earth's surface, yet there are other purposes for which it may be used.
For example:-To show the Antipodes of any place. The Antipodes of Great
Britain say is wanted.
Turn the cylinder until the Greenwich meridian is under the elastic cord. Then
note the latitude which is marked on the uprights r. r. at either side of the cylinder
of the place, in this case about 55° North of the Equator, consequently the latitude of
its Antipodes will be 55° South of the Equator. Turn round the instrument as a
whole one half turn, without rotating the cylinder, and the Antipodes of Great Britain
will be found on the meridian opposite, and indicated by the upright wire w.
To find the number of degrees sailed from a given point. The upper hour circle is
set so that 0° is exactly above the point from which the ship starts both being brought
under the elastic cord. Rotate the cylinder and upper hour circle until the point
wanted on the Earth's surface is under the elastic cord, then the number of degrees
sailed will be shown on upper hour circle. Thus say the 30th meridian East longitude
is the starting point, and the vessel sails until it reaches the 75th meridian West
longitude; it will be seen (as shewn on Sheet No. 2.) that the vessel has sailed
105° West.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
. (1) The use of a cylinder rotating upon its axis and having a map of the world
upon its cylindrical surface, to illustrate the revolution of the Earth about its axis, as
hereinbefore described.
(2) The application of the divisions of time in combination with the revolving
cylinder representing the Earth, as described.
(3) The use of the loose upper hour circle in combination with cylinder, as
described.
(4) The use of the external meridians, in combination with the loose upper hour
circle and cylinder for finding the time at various places on the Earth's surface, as
described.
(5) The use of the combination of the various parts as a whole, for finding the time
at various places on the Earth's surface, as described.
Dated this 21st day of November 1888
GEO. C. DOUGLAS & Co.,
41, Reform Street, Dundee,
Applicant's Agents.