US2094833A - Portable sundial - Google Patents

Description

Oct. 5, 1937. McAULlFFE PORTABLE SUNDIAL Filed Dec. 31, 1956 2 Sheets-Sheet l INVENTOR. 1055 MWuuF/Z.

BY I

% ATTORNEY.

Oct. 1937. J. M AULIFFE PORTABLE SUNDIAL 2 Sheets-Sheet 2 Filed Dec. 31, 1936 INVENTOR BY 1555p M9400:

WTTORNEY.

Patented Oct. 5, 1937 UNITED STAT ATENT oFFi 4 Claims.

This invention relates to a portable sun dial and has for its principal object the provision of a neat, compact, highly efficient unit which can be used to determine the hour of the day by the sun in any latitude, and which can be easily carried upon the person.

It is more particularly designed for use by campers, hunters, travelers, and explorers who might lose or damage ordinary time pieces and who have no access to a clock. It is also valuable ior instructing classes in schools, boy scout troops, etc., in the fundamentals of time determination and astronomy.

Other objects and advantages reside' in the detail construction of the inventiomwhich is designed for simplicity, economy, and efiiciency. These will become more apparent from the following description.

In the following detailed description of the invention reference is had to the accompanying drawings which form a part hereof. Like numerals refer to like parts in all views of the drawings and throughout the description.

In the drawings: i

Fig. 1 is a face view of one form of the improved portable sun dial as it would appear in use.

Fig. 2 is a side view thereof.

Fig. 3 is a face view of an alternate form of the invention.

Fig. 4 is a longitudinal section through the form of Fig. 3, taken on the line 44, Fig. 3.

Fig. 5 is a detail view of the roll operating mechanism of the form of Fig. 3.

The invention comprises a board In, of any suitable material such as cardboard, wood, bakelite fiber, etc. hinged flaps II and I2. The face of the flap H is provided with a narrow slot l3 and the face of the flap I2 is provided with a. vertical indicating line M. The flaps H and I2 are mounted upon suitable hinges 15 so that when not in use, they may lie flat against the board I0 and, when in use, they will stand upwardly at right angles to the surface of the board and parallel to each other. The slot I3 is aligned with the line H! on a horizontal line 4| across the board.

A latitude plate I6 is pivoted upon a suitable pivot rivet extending through the board I 0. Adjacent the rivet H, the latitude plate passes 50 through an arcuate slot l8, and is secured to the board on the rear face thereof. The plate I6 can be set at any desired angle by means of a clamp screw i9 which passes through an arcuate slot 20 and terminates in a clamping head 2| on the rear of the board.

At the top of the board are two Adjacent the slot 20 is an arcuate latitude index or dial 22 which is visible through a window 23 in the plate l6. An indicating arrow 24 indicates positions on the dial 22. The dial is indexe-d in all of the latitudes in which the inven- 5 tion is expected to be used. A scale running from 20 to 60 is usually all that is necessary.

A calendar is printed or engraved upon the plate I6, as shown at 25. The calendar is printed in two sections, with the months from July to 10 November at one side, and the months January '60 May at the other side, and with the two remaining months June and December at the extremities as illustrated. The calendar is accurately laid out by projection from a declination 15 scale id on the latitude plate 33. The declination scale is indexed to a mid-leap-year declination.

The two sections of the calendar are separated by means of a calendar slot 26. A flexible string 27 terminating in a plumbweight 28 extends 20 through the slot 26 from a suitable head on the back thereof. The weight 28 is slidable along the string 2? and may carry an indicating pointer 42.

Below -the plate Iii on the board II] is a removable time chart 2.! which may be clamped thereon 5 by means of clamp nuts 30. Upon the time chart 29 are two hour circles 3| and 32, the circle designating the A. M. hours, and the circle 32, the P. M. hours. The time indications of each hour circle are joined to those of the other by 30 means of a series of vertical guide lines 43. The charts 29 must be changed to correspond with the latitude of the place where the dial is to be used. As illustrated, a Lat. chart is shown on the board Ill.

In use, the user turns the flaps ll and i2 to the vertical position as illustrated. He then sets his latitude plate it on the dial 22 to correspond with the chart 29 and with the place of use. As illustrated, the plate is set at 40 latitude. He 40 now slides his string 2'! along the slot 26 to bring it opposite the approximate day of the month. He now swings the string 21 over the I2 noon mark on the hour circles (which is directly over the pivot point of the plate it) and slides the Weight 28 along the string until the point of the indicating arrow #12 indicates the exact noon point. The board is now set for use.

By holding the board ill in a plane intersecting the sun and inclining it to the proper angle, the suns rays will shine through the slot l3 forming an image on the flap l2. By tilting the board to the right or left, this image is brought directly upon the line 14 of the flap 12. At this time the string 27, due to its weight 28, is hanging vertiarrow 42 on the weight will indicate a certain one of the vertical guide lines 43. If it is morning the time can be read by following this line upward to the A. M. hour circle SI, and ifit is afternoon, the hour is read by following the line downward to the P. M. hour circle 32. As illustrated the dial is indicating either A; M. or P. M. depending, of course, on whether the dial is being used in the morning or the afternoon. By careful holding and accurate manufacturing, the time can be foretold accurately in five minute intervals. 7

Ordinarily, the device will be used in the same latitude at all times so that the chart 29 need not be oiten changed. For travelers or explorers, however, who are constantly changing their latitude, the charts must be constantly changed to correspond thereto. An alternate form of the invention to facilitate this constant change is shown'in Figs. 3 and 4. V r

In the latter form a latitude plate 33 similar to the plate I6, is pivoted on a side bracket clip 34, so' that it extends over the 12 noon point on a time chart printed on the face of a relatively long1paper strip 35. The strip 35 contains a series of time charts 36, each laid out for a' par-. ticular latitude. chart is to be used is indicated by an indexsuch as shown at 3?. The strip 35 reels and unreels from a pair of rollers 38 operated from a thumb button 39, on the side of the device. The thumb button may operate the rollers directly, or it may be connected with both rollers through suitable gears 44 and friction discs 45, as illustrated. This enables the user to quickly change his time charts to correspond to the latitude of the place of use. As each; chart is brought into position its 12 noon point mustbe brought directly beneath the pivot point of the latitude plate. This positioning is facilitated by printing an indication 45 on the strip at each time chart to be aligned with a corresponding indication 47 on the board.

While a specific form of the improvement has other on said board, there being a slot in one of said members and an alignment'i'ndication on the other of said members to; align said board The latitude for which each cally across the time chart 29 and the indicating with a ray from the sun; a movable plate on said board; a flexible member depending from said plateyan hour scale intersected by said flexible member when said board is in alignment with said ray; a latitude scale upon said board; means for aligning and setting said plate at a desired indication on said latitude scale; a calendar scale on said plate; and means for varying the posimember. when said board is in alignment with i said ray; 2, pair of rollers extending laterally of said board; and a-continuous strip of flexible ma-- terial reeling from one roll to the other for carrying a series of differing hour circles.

3. A portable sun dial comprising: a fiat board; a declination platepivoted adjacent one side edge of said board so as to swing over the face thereof; a latitudescale for determining the position of the said declination plate; means for locking said plate at any desired position on said latitude scale, said plate having a slot extending across its face at right angles to a radius extending to its pivot; a plumb line depending from said slot downwardly over said board; a calendar scale along said slot for determining the point of suspension of said plumb line; an hour scale below said declination plate over which said plumb line extends; and means for aligning said plate with a ray from thesun. I r

' 4. A portable sun dial comprising: a flat board;

a declination plate pivoted adjacent one side edge of said board so as to swing over the face thereof a latitude scale for determining the position of the said declination plate; means for locking said plate at any desired position on said latitude scale, said'plate having-a slot extending across its face atright angles to a radius extending to its pivot; a plumb line depending from said slot downwardly over said board; a'calendar scale along said slot for determining the point of suspension of said plumb line; an hour scale below said declination plate overwhich said plumb line extends; means for aligning said plate with a ray from the sun; and a head member on said plumb line preventing the' latter froinpulling from said slot, said head being clamped between said dec-. lination plate and said flat board. a

' a JOSEPH McAULIFFE.

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