US3158937A

US3158937A - Sun dial

Info

Publication number: US3158937A
Application number: US177025A
Authority: US
Inventors: Flinois Pierre L Jean-Baptiste
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-03-13
Filing date: 1962-03-02
Publication date: 1964-12-01
Anticipated expiration: 1981-12-01
Also published as: CH379409A; FR1294763A; CH282962A4

Description

De'c, 1, 1964 P. JEAN-BAPTISTE FLlNols 3,158,937

' SUN DIAL Filed March 2. 1962 `2` Sheets-Sheet 1 Dec. l, 1964 Filed March 2, 1962 P. L. JEAN-BAPTISTE FLINOIS SUN DIAL.

ZSheets-Sheet 2 which:

United States Patent O 3,358,937 SUN DIAL Pierre Laurent .lean-Baptiste illinois, 3S line Sibuet,

Paris, France Filed Mm. 2, i962, Ser. No. 177,025 vClaims priority, appiicationFrance, Mar. i3, 1961,

ia claims. ici ssa-sa) In all sun dials at present known kuse is made of the p shadow of a style on a table, which is a flat or vcurved i of. revolution one of the ends of which is open, permit only veryy diiicult reading of the shadows.

The present invention, which relates toma new sun dial free from the above-mentioned disadvantages, consists of a curved, open, suitably selected surface on which the hour lines are traced.

The curved surface is geometrically delined as a concave ruled surface which means that the surface is pro- Y duced by a straight line genera'trix moved in a position parallel with a stationary straight line along a curve which 'has no breaks and contains no change inthe direction of its curvature. Thus, this term'also includes cylindrical surfaces in which case, as is well known, the crosssection need -not'be a circular arc. Therefore, in the followingv spemication and in the claims the term concave cylindrical surface is intended to deiine broadly a concave ruled surface as stated above. v

Two parallel generatrices which bound the said concave cylindrical surface act as style.

The invention permits the serial production of inexpensive apparatuses which everywhere show V,the legal time to Within one minute. n

Many diiierent surfaces may be used. There are numerous mechanical constructions permitting their positioning in accordance with the place where nthey are used.

The present invention likewise relates to other arrangements which will be explained below in the description of the dials illustrated in the` accompanying Y drawings, 1n

FIGURE l is a'view in elevation offa rstsun dial according to the present invention and of the various means of support and-regulation of the said dial,

FIGURE 2 is a view of a detail of the said dial, FIGURES is a partial view of the sun dial illustrated in FIGURE 1, viewed in' the direction ot the` arrow f,

FIGURE 4 isa section along the line in FlG- URE 3, and l FIGURE 5 isa View of a second sun dial according to the present invention and of the various means of support and regulation of the said dial.

The sundial illustrated in Mouans 1 a; 4 is here constituted by a partialV cylinder of revolution l. The

i aises? Patented Dec. l, 19614 IC@ Y poles of the earth, the shadowscast by the generatrices la or lb on the vdial-formed by the cylinder 1 give the true local time. The cylinder lpbears a number of hour line ld, each of these lines corresponding to two times, differing from one another by live hours, depending on whether the shadow is cast by the generatrix laY or the generatrix lb. y

The cylinder l is solid with a stirrup 2 adapted to pivot around an imaginary line formed by the axes of two buttons 4 and 5 carried by a stirrup 3. This line is parallel to the generatrices of the cylinder l.

The stirrup 3 forms one side of a deformable triange channel member l@ carries a latitude graduation scale.

The channel member il? rests on a disc l2 which is fixed by screws ll3 to a base I4, having three feet formed by adjusting screws I5.

A screw i7 passing through the disc l2 serves as axis of rotation for the channel member 10 and passes through` A pointer. I9 pivoting around the axis of the button 4 'v is adapted to move in front of the plate i8, so that when the button Li is tightened the pointer 19 forms a rigid whole with the stirrup 2 and the cylinder l.

Finally,` the two stirrups 2 and 3 can be clamped together by a pin E@ or by the button 5.

For the purpose of installing this sun dial the pro- V cedure is advantageouslyas follows:

In order to set the channel lll horizontally, the positions of the screws l5 are adjusted in a manner known per se bymeans of a water level.

ln order to adjust the apparatus to latitude, the button '16 is loosened, the cursor 9 is so adjusted as to have its end on the latitude scale graduation provided on the bot- I must be brought parallel to the earths axis.

tom of the channel member lll, which corresponds to the latitude of the place where the sun dial is installed, and the button 16 is tightened again.

In order to adjust the apparatus, the axis llc of cylinder For this purpose it is now suliicient to bring the channel Vmember l@ into the local meridian plane. The cylinder l is clamped to the assembly 3, 9, it), S, by means Vof the pin 2li. The button 4 is loosened and consequently the pointer i9 released and the latter is set to the graduation of the longitude scale 18h corresponding to the longitude of the apparatus in relation to the Greenwich meridian.

The pointer 19 is finally clamped again by tightening the screw button 4 to the stirrup 2 and the cylinder l.

The pin Ztl is removed and the button 5 loosened. The

assembly l, 2, 19, can then be turned in relation to generatrices la andy lib, which coincide with the edges of said partialvcylinder l and are spaced from eachother a distance subtending an angle or arc a=l of said cylmeridian plane of the place where the sun dial is ,in-

7 stalled, passing through the axisof the said cylinder, and

when Vthese generatrices are parallel to the axisk of the ytonS.y e

The direction of` the apparatus is then'adjusted by loosening the button I6 and theV entire apparatus is ad-V the assembly 3, i8. The assembly l, Z, i9 is vturned `so that the pointer i9 is set-to the` graduation of the time curve lita corresponding to the date on which the instrument is installed. The assembly l, 2, l? is again clamped to the assembly f3, i8, by tightening the but- 'l justed so that the shadow of the generatrix la or lb v on the cylinder I indicates the legal time, and the but- Y ton 1d is finally tightened again. The Aapparatus is then in position.

Every ten days Vthe apparatus must be re-adjusted. For l this purpose the lbutton 5 is released and the pointer The Y said 1 vorder to bring the channel member l@ into t il@ is set to the graduation or the time curve ida corresv onding to the date of the correction and then the button 5 is tightened again.

The apparatus thus shows the legal time throughout the year to within l minute.

Diurnal shadow lines or lines of equal dates can easily be traced on the dial of this instrument. The latter then becomes self-regulating because it can be installed Jithout the time being known.

ln the apparatus illustrated in FlGURE 5, the stirrup 2 is mounted directly on the raised end 9b of the cursor 97. The button 5 and also the plate i8 and its pointer i9 are eliminated. The pin 2@ is then placed on one of the sides 2o of the stirrup 2 and on a part 2l, solid with a part Z2. rticulated by means of the hinge d on the bar 8.

The remainder of the apparatus is similar to that illustrated in FlGUltlS l and 2.

ln order to install this last-mentioned sun dial, the procedure may be as follows:

ln order to set the channel member l@ horizontally to regulate the apparatus for latitude, the procedure is as before.

ln order to orient the apparatus, that 's to say in meridian plane passing through the place where the sun dial is situated, the procedure is as vfollows: the pin 2u remains engaged, the button it? is loosened, and the instrument is brought into a position such that the diilercnce between the time indicated on the cylinder it by the shadow cast by the generatrices and lo and the legal time is equal to a Value given by a table in dependence on the date on which the instrument is being installed and on the longitude of the place in relation to the Greenwich meridian. The button iti is then tightened. rEhe channel member itl is then in the meridian plane of the place.

ln order to adjust the position of the cylinder, the pin is removed and the cylinder l turned until the aforesaid difference is equal to zero, and the assembly is clamped by means of the button 4.

The apparatus is then adjusted in place.

Every eight days the button d is loosened and the cylinder l' and its stirrup 2 turned until it indicates the legal time, and the button i is tightened again.

lt should be observed that the accuracy of the instruments described is twice as great as that of cylindrical dial instruments having axial styles, because in the instruments according to the present invention the generatrices la and lib are in the dial surface, whereas in the cylindrical instruments having an axial style the style is in the centre.

Tie present invention is not limited to the examples described. Thus, tor example, the dial is not necessarily constituted by a split cylinder of revolution. This dial may in fact be constituted by a skew surface bounded by two parallel generatrices. ln particular, where use is made of a hyperboloid of one sheet, the dial carries crossing hour lines.

l claim:

l. A sundial apparatus, comprising, in combination, opaque dial plate means having a concave cylindrical indicating surface adapted to be exposed to incident sunlight and to unobstructed view, and dened geometrically as a portion of a cylindrical surface extending between two parallel edges each coinciding with a generatrix of said indicating surface and being located in generally opposed direction across said indicating surface, said indicating surface being provided with a plurality of index lines respectively associated with different hours of the day; and means for orienting said dial plate means at least depending upon latitude and longitude of the location of the apparatus, so that the time indication is cliected on said indicating surface of the dial plate means in relation to said lines by the edge of the shadow l of a portion of said opaque dial plate means, said edge or" the shadow being a projection by sunlight of one of said edges of said dial plate means.

2. A sundial apparatus, comprising, in combination, opaque dial plate means having a concave indicating surface adapted to be exposed to incident sunlight and to unobstructed view, and defined geometrically as a portion of a cylindrical surface extending between two parallel edges each coinciding with a generatrix of said cylindrical surface and being spaced from the other generatrix a predetermined distance substantially diametcally across said cylindrical surface, said indicating surface being provided with a plurality of index lines respectively associated with different hours of the day; and means for orienting said dial plate means at least depending upon latitude and lonvitude of the location of the apparatus, so that the time indication is eilected on said indicating surface of the dial plate means in relation to said index lines by the edge of the shadow of a portion of said opaque dial plate means, said edge of the shadow being a projection by sunlight of one of said edges of said dial plate means.

3. A sundial apparatus, comprising, in combination, opaque dial plate means having a concave indicating surface adapted to be exposed to incident sunlight and to unobstructed view, and defined geometrically as a portion of a cylindrical surface extending between two parallel edges each coinciding with a generatrix of said cylindrical surface and being spaced from the other generatrix a predetermined distance subtending a arc of said cylindrical surface, said indicating surface being provided with a plurality of index lines respectively associated with different hours of the day; and means for orienting said dial plate means at least depending upon latitude and longitude of the location of the apparatus, so that the time indication is effected on said indicating surface of the dial plate means in relation to said index lines by the edge of the shadow of a portion of said opaque dial plate means, said edge of the shadow being a projection by sunlight of one of said edges of said dial plate means.

4. A sundial apparatus as claimed in claim 1, wherein said opaque dial plate means include support means turnable about an axis parallel with the geometrical axis of said cylindrical surface, and wherein said means for orienting said dial plate means include pivot means turnably supporting said dial plate support means for turning movement about said axis and clamping means for setting said dial plate means in a desired oriented position.

5. A sundial apparatus as claimed in claim 3, wherein said opaque dial plate means include support means turnable about an axis parallel with the geometrical axis of said ruled surface, and wherein said means for orienting said dial plate means include pivot means turnably supporting said dial plate support means for turning movement about said axis.

6. A sundial apparatus as claimed in claim 4, wherein said means for orien'ting said dial plate means include a triangular supporting frame composed or" a plurality of frame members, one frame member carrying said pivot means and being adjustable to a desired inclination relative to a second one of said frame members.

7. A sundial apparatus as claimed in claim 5, wherein said means for orienting said dial plate means include a triangular supporting frame composed of a plurality of frame members, one frame member carryinggsaid pivot means and being adjustable to a desired inclination relative Ito a second one of said frame members.

8. A sundial apparatus as claimed in claim 6, wherein said triangular frame comprises a plurality of hingedly connected frame members, one of said frame members being composed of at least two portions, one of which is longitudinally adjustable relative to the other portion for Varying the length of that particular frame member, said other portion carrying a latitude scale and said adjustable portion being movable relative to said scale so that it can be set to a position relative to said scale which determines a desired inclination of said axis of said dial plate means.

9. A sundial apparatus as claimed in claim 8, wherein said one frame member carrying said pivot means includes a plate member carrying a longitude scale, and wherein said dial plate support means include an index member movable relative to said longitude scale for indicating the setting of said dial plate means corresponding to a particular longitude when said dial plate means are correspondingly turned about its axis.

10. A sundial apparatus as claimed in claim 9, including an indexed time correction curve arranged on said plate member for cooperation with said index member and permitting adjustment of said dial plate means in consideration of the difference between apparent time and clock time.

References Cited in the le of this patent UNITED STATES PATENTS 170,423 Wheeler Nov. 23, 1875 825,319 Hewitt July 10, 1906 10 3,031,763 Jewett May 1, 1962 FOREIGN PATENTS 915,671 France July 29, 1946

Claims

2. A SUNDIAL APPARATUS, COMPRISING, IN COMBINATION, OPAQUE DIAL PLATE MEANS HAVING A CONCAVE INDICATING SURFACE ADAPTED TO BE EXPOSED TO INCIDENT SUNLIGHT AND TO UNOBSTRUCTED VIEW, AND DEFINED GEOMETRICALLY AS A PORTION OF A CYLINDRICAL SURFACE EXTENDING BETWEEN TWO PARALLEL EDGES EACH COINCIDING WITH A GENERATRIX OF SAID CYLINDRICAL SURFACE AND BEING SPACED FROM THE OTHER GENERATRIX A PREDETERMINED DISTANCE SUBSTANTIALLY DIAMETCALLY ACROSS SAID CYLINDRICAL SURFACE, SAID INDICATING SURFACE BEING PROVIDED WITH A PLURALITY OF INDEX LINES RESPECTIVELY ASSOCIATED WITH DIFFERENT HOURS OF THE DAY; AND MEANS FOR ORIENTING SAID DIAL PLATE MEANS AT LEAST DEPENDING UPON LATITUDE AND LONGITUDE OF THE LOCATION OF THE APPARATUS, SO THAT THE TIME INDICATION IS EFFECTED ON SAID INDICATING SURFACE OF THE DIAL PLATE MEANS IN RELATION TO SAID INDEX LINES BY THE EDGE OF THE SHADOW OF A PORTION OF SAID OPAQUE DIAL PLATE MEANS, SAID EDGE OF THE SHADOW BEING A PROJECTION BY SUNLIGHT OF ONE OF SAID EDGES OF SAID DIAL PLATE MEANS.