An Improved Sun Dial.
Year: 1891

page_text: Date of Application, 12th Sept., 1891-Accepted, 21st May, 1892
COMPLETE SPECIFICATION.
An Improved Sun Dial.
I, MAX KÜSTER, Dr. Med. of Königstrasse, Freienwalde 70, in the German
Empire, do hereby declare the nature of this invention and the manner in which
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
This invention relates to an improved sun dial and my invention consists of the
several parts and combinations of the same hereinafter described and set forth.
The instrument consists mainly of a dial a compass and a ray searcher the
said ray searcher serving also as a gnomon.
The dial is either fixed in which
case the ray searcher is shifted in order to determine the time or the dial and ray
searcher are both fixed together and the magnetic needle is used to show the time.
In order that my invention may be more readily understood reference is made
to the accompanying drawings in which similar letters denote similar parts
throughout the several views.
Fig. 1. is a plan of a pocket sun dial having a fixed dial and a movable ray
searcher.
Fig. 2 is a vertical section through Fig. 1.
Figs. 3 and 4 shew in plan and section a sun dial having a fixed dial and
ray-searcher the magnetic needle in this form shewing the time.
Figs. 5, and 6 shew an instrument in plan and section in which the ray searcher
is fixed and provided with a pointer and the dial is moved with the magnetic
needle.
Figs. 7 and 8. shew the adaptation of one of the above devices to a fixed
sun dial.
The combined ray searcher and gnomon a (Figs. 1 and 2.) the angle of which
depends upon the situation of the locality where the sun dial is used is provided
with a transverse arm carrying a mirror said arm being fixed a short distance
from the end of the said ray searcher and the latter also carries a projecting wall d.
The searcher a can be revolved on its pivote by means of the handle. The dial g
(the graduations or divisions on which are made according to the latitude of the
county or locality in question) is fixed on the inside to the back of the case.
If now it is required to find out the time the instrument is brought into such a
position that the magnetic needle i points north and south on the compass (due
allowance being made in the calculation for the magnetic variation).
The ray searcher a is now turned towards the direction of the sun until the
reflected light from the mirror c on the wall d appears sharply defined and equally
divided by the shadow of that part of the searcher projecting before the mirror.
In such position the pointer of the ray searcher will shew the correct time upon the
divisions of the dial. The sun dial represented in Fig. 1. is only intended for use
when the sun is obscured by clouds or in dull weather but if provided with a dial
graduated as in Fig. 3 it can also be used in sunshine since in the latter case the
searcher must be placed diametrically opposite so that the shadows thrown direct
by the sun on wall d appear sharply defined and equal in size the pointer will then
shew the same hour but on the other side of the dial.
In the device shewn in Figs. 3 and 4 the position of the ray searcher & is fix
with regard to the dial (in the figure being shewn opposite the hour eleven). If
the instrument is now turned round until the reflections on wall & are equal in size
the magnetic needle will point to the correct time (F). It should be mentioned
that the position of the ray searcher in relation to the dial is varied according to
the situation of the locality in which the instrument is used on account of the
variations in the magnetic meridian. In Figs. 5 and 6 a modification is shewa in

page_text: which the dial is attached to the magnetic needle 2 and held by the same in the
proper position so that the meridian of the dial covers the north and south line of
the compass. In order to read off the time in this case the ray searcher is
brought into the proper position (i.e. so that the reflection appears clear and of the
proper form) and the magnetic needle with the dial allowed to come to a standstill
when the pointer on the ray searcher will stand above the figures of the dial which
indicate the time. In order to obtain a clear and sharply defined reflection in dull
or cloudy weather it is advantageous to arrange a plate on the searcher of some
crystal such as tourmaline which has the property of allowing parallel rays only to
pass through it consequently causing a sharper reflection.
Figs. 7 and 8 represent the device adapted to a pedestal sun dial which may be
placed in any advantageous position. The arrangement is, in its main points, the
same as that shewn in Figs. 1 and 2. The searcher in this case may be turned
round by means of the button p to the spindle of which is attached the mirror of
the searcher said spindle further supporting the magnetic needle s. The reflection
in this case is thrown directly on the side of the casing or stand on which the
dial is arranged.
"
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. In a sun dial adapted for use in dull and cloudy weather as well as in sunlight;
a combined gnomon and ray searcher a having a transverse arm & mirror c and wall
or rim d said gnomon being adapted to be rotated from the outside of the casing in
combination with a dial and magnetic needle arranged substantially as described
and illustrated in Figs. 1 and 2 of the accompanying drawings.
2. In a sundial the combination of a ray searcher and gnomon k and a dial g¹
fixed thereto with a magnetic needle for pointing out the hour substantially as
described and illustrated in Figs. 3 and 4 of the accompanying drawings.
3. The combination of the dial attached to the magnetic needle and the
combined ray searcher and gnomon having a pointer o substantially as describe:! and
illustrated in Figs. 5 and 6 of the accompanying drawings.
4. The adaptation of the device to a stationary sundial consisting of the stand w
having a revoluble ray searcher mounted on the spindle and having button or
handle in combination with a magnetic needle s substantially as described and
illustrated in Figs. 7 and 8 of the accompanying drawings.
5. The improved sundial arranged constructed and operating substantially as
described and illustrated in the accompanying drawings.
Dated this 12th day of September 1891.
HORN & SON,
Applicant's Agents.