US1875756A - Sundial construction - Google Patents

Description

p 6, 1932- ST. JOHN OSULLIVAN 1,375,755

SUNDIAL CONSTRUCTION Filed Feb. 14, 1928 3 Sheets-Sheet 1 l I 1 J 5 g Rx E as g E E a Inventive". 1% Jo/z 21, 01? ullz'vazz p 6, 1932- ST. JOHN OSULLIVAN SUNDIAL CONSTRUCTION Filed Feb. 14, 1928 3 Sheets-Sheet Invenlar- J John auilz van.

.flforneys P 6, 1932- ST. JOHN OFSULLIVAN 1,875,756

SUNDIAL CONSTRUCTION Filed Feb. 14, 1928 5 Sheets-Sheet 3 Invezz tor.

1ft John gullz'van- I \flfiorneys.

Patented Sept. 6, 1932 PATENT 1 OFFICE ST. JOHN OsULLIvAN, or SAN JUAN oArIsTRANo, CALIFORNIA suNnIAL cousrrwc'rrou Application-filed February 14 1928.; Serial No. 254,254.

The object of this invention is to enable a sun-dial to indicate with approximate accuracy mean solar time, standard time or time other than apparent solar time, on each day of the year. I

The chief feature of the invention consists in means for mounting the dial and its gnomon so the same will be revolubly adjustable on the axis or stile of thegnomon, 1m and means for giving the same said revolubly adjustable movement, which means is provided with date indications so that said dial and gnomon may be adjusted 'and'held in a position to cause them to fulfill the objects stated above. ,To that end the device should be mounted when in use so that the axis or stile of the gnomon will be substantially parallel with the axis of theearth and the dial be revoluble about that axis to the 20 desired adjusted position."

In the explanation that follows, mean solar timewill be principally referred to, but standard time or other time,may be indicated with equal facility by shifting the pointers 93 fast or slow as required by the longitude of the place. It is known that the ordinary sun-dial indicates apparent solar time, which agrees with mean solar time only on four days in the year, namely, April 16, June 14,- September 1 and December 25;

In this invention preferably the dial is a flat plate and gnomon is rigidly secured and perpendicular thereto so that the plate may be horizontal at times and the stile of the gnomon in angular relation to the'plate so that when the plate is horizontalthe stile of the gnomon is substantially parallel? with the axis of the earth, and means secured to the gnomon for swinging the dial and gnomon on an axis substantially the same as the stile of the gnomon and substantially at and parallel with the indicating portions of the gnomon, and a date indicating dial is asw sociated with the means foreflecting said swinging movement so that the device can be set for a certain date and the dial thus be in position to indicate standard or other time than apparent solar time.

By this means the sun-dial is turned? eastwardly or westwardly away from the celestial meridian which it normally faces, .until it arrives at the properposition to indicate mean solar time. It is to be noted that on the four. dates mentioned above anadjust: ment eastwardly or 'westwardlyis' not necessary because'on' those dates mean: solar time and'apparent solar time agree f .3 This attachment is furthermore provided with a. scale composed of twelvegroupsf of date lines, one group foreach month inath g0 year, inscribed radially onja disc which'is mounted rigidly on :the supports of the mechanism; The attachmentihas also another disc,- mounted rigidly on-a shaft whose axis is parallel with 'the gnomon with which it 68 is rigidly'connected. This second disc is concentrically superposed on the first disc, and is rotatable uponit; This superposed rotary disc is provided atthe' outer edge 'on its face withtwelve radially inscribed'monthly pointers, one for each month of the: year,- and 'is capable of being turned so as to cause the monthly pointers thereon tojjregister-with any one of the datelines inthegroup of lines for the corresponding month on" the other disc. The effect of "such an" adjustment is simultaneously to cause the sun-dial to revolve until it faces a point on' the celestial sphere located eastwardl-y o'r westward'ly from the celestial'meridianas manyd'egrees 80 and minutes of are as the sun passes over in the-corresponding equation of time for 'the date on which the adjustmentmade The full nature of this invention will be understood from the accompanying draw ings and following description andclaims, wherein one form of said invention is p'rea sented to enable the invention to be under stood, but the invention is notlimited to the particular construction illustrated herein.

' In. the drawings herein to show one form of the invention: i l

Figure 1' is a side elevation of such a sun'- dialand the attachment, the partsthereof shown in the, position for indicating apparent suntime, that is, with the dial face thereof horizontal and the gnomonplate in the meridional plane Fig. 2is a plan view of the sun-dial with'the attachment as shown Fig; 1" and with the sun-"line shadowinm dicating two oclock in the afternoon. Fig. 3 is an elevation of the adjusting discs for vsetting the sun-dial to indicate time other than apparent sun time for any day in the year. 7 Fig. 4 is an elevation of the front of the sun-dial with the attachment, that is, from a position at the left hand of what is a shown in Fig. 1, and altered position of parts thereof being indicated by dotted lines. Fig. 5 is a perspective view of the sun-dial with the attachment. Figs. 6, 7, 8 and 9 are elevations of the adjusting discs, such as shown in Fig. 3, adjusted for indicating standard time at San Juan Capistrano, California, on

with and extending upwardly therefrom, as

is very common in sun dial constructions. The dial 20 herein shown is rectangular and substantially square and hasupon it in rectangular form the hours of the day indicated by- Roman numerals, as is familiar in the gnomonic art, and along the outer margin of "said dial there are lines 22 leadingfrom the hour numerals and there are half-hour marks 23 and quarter-hour marks 24, as shown. These lines 22, 23 and 24 coincide withthe sun line 25, or shadow cast by the edge 26 of the gnornon 21 at themomen't the I shadow falls upon them.

The foregoing is substantially a common sun-dial; The dial 20 is mounted usually and'herein so as to behorizontal, and the shadow-casting edge of'the gnomon is parallel with the axis of the earth and faces the celestial meridian. This invention, however, is not limited to being attached to a sun-dial having a plane dial face, as it may be attached to an equinoctial sun-dial, or with one having a dial face that is co'ncaved and spherically disposed, as'shown in applicants Patent 1,651,621, patented December6,1927. 7 l I I The dial 20, as above described, has heretofore been mounted usually in a stationary position, whereas in this invention it is mounted so as to be capable of being tilted 'or. of receiving a revoluble movement with the axis of such movement extending'through the gnomon on the line parallel withjthe shadow-casting edge of the gnomonand consequently when properly mounted also parallel with the axis of the earth. Therefore, the dial 20 has a spindle '30 at its lower'end mounted in a post 31 extending up from and secured to a horizontal base plate 32, or

frame, as shown in the left hand part of Fig. 1. To the upper right hand of the gnocoincide'with mean solar time.

mon 21 there is secured rigidly a triangular plate 33 so as to extend at a right angle from the shadow-casting edge 26 of the gnomon and from the upper end of said plate 33 there is a spindle 34 having bearing in the upper 1 36' rigid on the shaft 37 that is mounted on the stationary disc 35 and herein centrally thereof, and having on its inner end a rigid pinion 38 held in place by the collar 39 and said rigid pinion 38 engages a segmental rack 40 on the lower end. of the plate 33 that is secured to the gnomon. This is shown in Figs. 4, 5 and 13. By turning the hand wheel or knob 36 the plate 33,shown in Figs. 3'and 13, obviously can be swung on its axis at 34 from the full line position shown to the dotted line position shown in either direction, and accordingly will swing or tilt the dial 20, as shown in the drawings, and such movement, in one direction or the other will advance or retard from the normal position the shadow line 25 made by the sun. 7

Assuming the position ofthe parts shown in Fig. 2 to be the normal position as indi eating 2 oclock in the afternoon, if the dial 20 should be swung to the left, as shown by dotted lines inFig. 4 it is obvious that'the shadow line '25 would fall beyond the 2 oclock mark or somewhere between the 2 oclock mark and the 3 oclock mark on the dial. If, on the other hand, the dial should be swung in. the opposite direction, the shadow line would fall on the dial in advance of the 2 oclock mark.

- The foregoing adjustment by swinging of the dial is rendered necessary to adapt the dial for'indicating correctly some other time besides apparent solar time, because for mean solar time, if theparts were in the normal position shown in Fig. 2, the shadow line would be on one side or the other ofthe 2 oclock mark, except on April 16, June 14,

September 1 and December 25th, when the shadow line of apparent solar time would On all other days of the year the apparent solar-time either faster orv slower than mean selar time. It is necessary, therefore, that the dialbe given a revoluble movement on an axis parallel with the shadow-casting edge of the gnomon and therefore of the axis of the earth over such an arc,'or in other words, over such angular distance east or west from the celestial meridian, .as is, necessary'to cause the shadow line to indicate the correct mean solar time instead of apparent solar time." The are, or angular distance, necessaryto make this correction between sun-dial time and mean time is calculated from the equation of timefor a given day or date as set down in the American Ephemeris. One degree of arc equals four minutes of time. In other'words, if the equation of time is plus 4 minutes on a certain date, itwill be necessary on that date torevolve the dial to the west over an arc of one degree inorder to cause'it to indicate mean solar time instead ofapparent solar time.

In order to adjust the position of the dial by means of the herein attachment for a certain day of the year, a rotary disk 45 is secured on the shaft 37 so as to turn with said shaft as the dial 20 is being swung or ad justed from the normal and horizontal position. In the form shown, thisdisc 45 has indicated on it, as seen in Figs. 2 and 3, radially disposed month pointer lines 46 in proper positions, and themonths marked on the disc adjacent the pointer corresponding therewith. As shown, these month pointer lines are not uniformly distributed or equally spaced. from each other, but are placed where they are required to'be located in order to cooperate with the lines or pointers 47 on the surrounding and adjacent stationary disc 35. This stationary disk is divided into twelve sections by division lines 48, but they are not equally spaced from each other, and in each section the days of the month are indicated at 49. However, in order that the indication lines and numerals may be spaced far enough apart to be easily identified and read, all days of the month are not given, but only certain days thereof, usually every fifth day.

The scale composed of the date lines on the fixed disc 35 is valid at any point of latitude or longitude in the world; and the angular distances of the twelve monthly pointer lines one from the other are likewise unchangeable for any place on earth; but the angular distance of each monthly pointer line from the line indicating the first of the month in the respective group of date lines, when the dial face is at normal, varies according to the longitude of the place and kind of time to which it is desired to make the correction. This variation is uniform for all the pointers, thus preserving the respective angular distances between each pointer and its neighbor. At San Juan Capistrano, Long. 117 deg. 39 min. 50 sec. W., in making the correction to standardtime, these monthly pointers are all shifted 2 deg. 10 sec. in a clockwise direction on the disc to cause the sun-dial to be 9 minutes and 21 seconds slower than mean solar time, this being the equivalent in time for the are 2 deg. 20 min. and 10 sec., the difference between the longitude at San Juan Capistrano Some curious features are present in these (11868 for indlcating standard tim-eyat San Juan Capistrano, and in their operation. Thus, the hand operated disc 45 is advanced to theright, or clockwise, from Nov. 4 until February 10 is reached; then, after standing for five days, the movement is reversed, and I the disc revolves to the left through the rest of February, until the fifth of May is reached. It then remains stationary for twenty days and at the end of this period of days starts off again in the opposite direction, that is, to the right, or clockwise, and continues moving in this direction until J uly 20th,where it halts for eleven days, and on August 1 begins again its movement to the left until November 1, where it tarries for four days, and then starts once more its journey to the right. Thus, it

changes its direction every three months,

approximately, and at the time of changing the movement of thedisc is so slight from day to day that it is difficult to indicate it on so small a scale as is here shown, buteven for February, May, J uly'and November the scale on the stationary disc of the sun-dial is substantially accurate for those months when the attachment is made with thisstationary disc twelve or more inches .in diameter.

In the'form herein shown,gears are used'to multiply by ten the distance of are necessary to revolve the dial face on any given day. The purpose of multiplying the distance is to widen the date-line spaces in the stationary disc'and thusfacilitate the reading of the date lines,and render the'sun-dial capable of finer adjustment. j

By the word axis is meant a line substantially concentric with thebearing 30 and 34, around which line or axis the gnomon and dial revolve. It is substantially at and parallel with the shadow-casting edges and theoretically the axis of the gnomon in' this con struction is substantially the same as the stile or shadow-casting edge.

- I claim:

1. Means for revolubly adjusting the dial of a sundial construction wherein the dial is flat and the gnomon is rigidly secured and in a plane perpendicular thereto, includ ing a frame in which the dial and the gnomon unit is revolubly mounted on an axis substantially at and parallel with the shadowcasting edge of the gnomon, a toothed segment secured to the gnomon and extending at right angles from the axis thereof, means for engaging the toothed end of said segment andcausing it to revolve and give the desired Iii-J movement to the dial and gnomon, and a date indicating plate secured on said last mentioned means for determining a desired position of said dial and gnomon, whereby they would indicate time other than solar time.

2. Means for revolubly mountingand adjusting a sundial to indicate time other than apparent solar time, including a horizontal dial, a vertical gnomon secured thereon, a base plate, a relatively large frame plate secured to the base plate for pivotally mounting the upper end of the gnomon therein, a relatively small arm for pivotally mounting the other end of the dial and gnomon unit therein, a segmental plate secured-to the upper end of the gnomon and having gear teeth in its lower end, a shaft extendingperpendicular through said large plate having a gear on its inner end for meshing with the teeth of said se mental plate, a dial plate secured to said. shaft and overlapping said frame plate, said dial having radial pointer indications thereon, and said frame plate having date indications thereon surrounding the dial with which said pointer indications may register, whereby the dial and gnomon may be revolubly adjusted to set them to indicate time other'than apparent solar time;

3. Means for revolubly adjusting a sundial to set it to indicate time other than solar time, including a frame, a dial, a gnomon, said dial being mounted on said frame with its face normally horizontal, and said gnomon revolubly mounted on said frame so the axis and shadow casting edge thereof are parallel with the axis of the earth, a stationary disk secured to the frame and which extends at a right angle to the axis of the gnomon,which disk is circular and provided'with radial date lines, means including a rotary disk for givmg said dial revoluble movement about the axis of the gnomon, said rotary disk having a pointer on the margin thereof for each month in the year arranged to coact with the date lines on the stationary disk for enabling the'device to be set for indicating the correct time other than sun time for a certain day in the year. I i

4:. Means for revolubly adjusting a sundial to set it to indicate time other than apparent solar time including a stationary base plate, a dial, a gnomon secured on said dial, means on said base plate for pivotally mounting said dial and the gnomon so that the dial may be normally horizontal and the shadow casting edge of the gnomon be parallel with the axis of the earth, one of'said means for mounting the dial and the gnomon consisting of a stationary disc at a right angle to the shadow casting edge of the gnomon which has date lines thereon for the months of the year and days of each month, a plate secured to the gnomon adjacent to said last mentioned disc and having its lower end provided with a rack, a hand operated shaft mounted in the center of said stationarydisc and having a pinion secured thereon for engaging said rack be set to give the correct time other than sun time for a certain time in the year.

In witness whereof I have hereunto afiixed my signature. 7

' ST. J OHN-O SULLIVAN.

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