US2173545A - Device for obtaining solar observations - Google Patents

Description

Sept. 19, 1939. C, H WALL DEVICE FOR OBTAINING SOLAR OBSERVATIONS Filed May 8, 1939 INVENTOR vm/de /f n/q/z gA-TTORNEYS` i;

Sept. 19, 1939 c, H, WALL v 2,173,545

5 Sheets-Sheet 2 Sept. 19, 1939. C, H, WALL A '2,173,545

DEVICE FOR OBTAINING SOLAR OBSERVATIONS Filed May 8, 1939 3 Sheets-Sheet 3 SOLAR AZIMUTH DATE /m/se 46F SUN's HomgoNT-Ax. VERTvcAL SPEED LATITUDE 40 00.0

4 l, l, h (observzdmjaaf' Il- I4. 33 168 H- |7-2| 176 H20-I7 0094/ h (Corrected) 43 SUN TIME RATE H. C. RATE. V.C. L, START 000' D 2 43| Patented Sept. 19, 1939 UNITED STATES PATENT OFFICE DEVICE FOR OBTAINING SOLAR OBSERVATIONS 8 Claims.

lViy invention relates to a device for obtaining solar observations. It has to do, more particularly, with a device for use in conjunction with -an engineers or surveyors transit or theodolite to make solar observations in order to nd the direction of a line; usually referred to as meridian, azimuth, or bearing.

Solar observations are used at the present time by engineers and surveyors in determining the azimuth of a given line. However, at the present time these observations are employed only where great accuracy is not required. For accurate work, engineers and surveyors in making surveys prefer to make observations on Polaris. Although great accuracy can be obtained in this manner, Polaris observations must be made at night and require special arrangements for illuminating the field of view and the mark.

As is well known to surveyors and engineers, the azimuth of any line in a survey may be determined by measuring the horizontal angle between the line itself and the direction of the suns center, as well as the altitude of the sun, and then soiving the spherical triangle, polezenith-sun, for the spherical angle at the zenith. This computed angle is combined with the measured horizontal angle to obtain the azimuth of the survey lin-e.

Solar observations, as indicated, are used at the present time to obtain the direction of a line. However, these observations are not accurate and cannot beV performed very quickly. Also, with the present solar observation methods, it is not possible to accurately measure the speed of the sun, both horizontally and vertically, in a quick and elici-ent manner.

The solar observation methods commonly employed at the present time consist of the quadrant-tangent method and the center-tangent method. With both of these methods, the vertical and horizontal cross-hairs of the transit are employed. These observations are taken either by looking directly at .the sun with a transit equipped with a darkener attached to the eyepiece or by using a screen spaced a few inches back of the eyepiece upon which the image of the sun together with the shadow of the crosshairs will focus when the transit is pointed at the sun. With the quadrant-tangent method, the observations are made by adjusting the telescope of the transit until the edges of the image are tangent with the vertical and horizontal hair lines in either quadrant formed thereby. With the center-tangent method,'the observations are made by adjusting the telescope of the transit until the edge of the image is tangent with one of the hair lines and the center of the image is on the other line. With both of these methods, it is extremely diicult to obtain any high degree oi accuracy. In the quadrant-tangent method it is necessary to simultaneously watch two points of tangency 90 degrees apart. In the centertangent method, one point of t-angency must be watched and the center of the image must be located accurately on one of the hair-lines. The reading of the angle on the instrument must be taken when the suns image is located exactly as indicated above. It isV very diificult to get the image rof the sun located accurately in the manner indicated and considerable time must be consumed in doing this. Furthermore, with these methods in order to determine the speed of the sun with any degree of accuracy, it is necessary to permit the sun to travel through a distance lequal toY its full diameter which consumes a considerable period of time. One of the .objects of my invention is to provide a device for obtaining solar observations, in order to find the azimuth oi a line, in a highly accurate and quick m-anner.

Another object of my invention is to provide ardevice for obtaining solarr observations which may be used in taking solar observations in a manner greatly simplified as compared to the ordinary methods of making solar observations.

Another object of my invention is to provide Va device of such a nature that the observations may be made in such a manner that pointings can be taken directly and accurately on the center of the sun.

Another object of my invention is to provide a device of the type indicated which is of such a nature that the speed of the sun both horizontally and vertically may be accurately determined.

Another object of my inventionis to'provide a device for use` in obtaining solar observations which may be employed with the ordinary transit now commonly in use.

Another object of my invention is vto provide' a device of the type indicated which is very simple and inexpensive to make and which may be readily attached to or removed from the ordinary transit.

In its preferred form, my invention contemplates the provision of a device which is adapted to be attached to the Ordinary surveyors transit or other similar'instrument. device embodies a screen Whichis disposed a short distance back of the eyepiece of the telescope. Between the screen and the eyepiece, I provide a shield which is so designed as to facilitate solar observations. 'I'he shield is made of opaque material but is provided with suitably arranged apertures for permitting a portion of the rays of the suns image to pass beyond the shield and focus on the screen when the telescope is pointed at the sun. The shield is so designed that pointings can be taken directly on the center of the sun. The shield casts a symmetrical shadow on the screen which has at least three points uniformly disposed about the axis of the tel-escope with which the edge of the suns image may be accurately registered by means of proper adjustment of the vertical and horizontal angles of the tele-l scope. The result is the` samey as accurately sighting the intersection of the vertical and horizontal cross-wires on the center of the sun.

The preferred embodiment of my invention is illustrated in the accompanying dr-awings wherein similar characters of reference designate corresponding parts and wherein:

Figure l is a perspective view of an engineers transit showing my solar observation attachment mounted thereon.

Figure 2 is a perspective View of the screen and cooperating solar shield.

Figure 3 is a view partly in side elevation and partly in section illustrating the complete attachment.

Figures 4, 5, 6 and 7 are plan views of the screen showing the shadow which will be cast thereon by the shield when the transit is directed at the sun, the different iigures illustrating different positions of the suns image.

Figure 8 is an enlarged plan view of the shield.

Figure 9 is an edge View of a portion of the shield showing the means for indicating whether or not the shield is perpendicular to the' axis of the telescope of the transit, the shield being in this instance in proper perpendicular relationship.

Figure 10 is a similar view but showing the shield in a position where it is perpendicular to the axis of the telescope.

Figure 11 is a plan view of a screen which may be employed without using the shield.

Figure 12 is a combined perspective and diagrammatic view illustrating how solar observations may be made to determine the direction of a line.

Figure 13 is a table which should be used in conjunction with Figure 12 to illustrate an example of determining the direction of a line by solar observations made with my device.

With reference to the drawings, in Figure 1 I have illustrated an engineers or surveyors transit I which may be of any ordinary form. It includes the telescope 2 which is fulcrumed, for movement in a vertical plane, as at 3. Suitable means is provided on the instrument for accurately adjusting the vertical and horizontal angles of the transit in the usual manner. My solar observation attachment is indicated generally by the numeral 4 in Figure 1.

As indicated best in Figures 1 and 3, my attachment includes a telescoping rod comprising a section 5 and a section 6. The section 5 receives the section 6. The hollow outer end of the section 5 is provided with a plurality of longitudinal slits 1. The end of the section 5 has its exterior surface threaded, as indicated at 8, and receives a cooperating threaded nut 9. Contacting inclined surfaces are provided at Iil o'n the end of member 5 and on the interior of the nut 9 and are so arranged that when the nut is rotated in a proper direction, the end of the member 5 will grip the section 6. Thus, a telescoping rod structure is provided which is of such a nature that the length thereof may be readily varied.

The end of the section 5 is provided with a clamping yoke II which is adapted to embrace and to be clamped upon one of the trunnion portions I2 which is formed as part of the telescope 2. This member Il carries a stationary gripping member I3 and a movable gripping member I4 which have their inner sides so shaped as to t the curved portion I2. The member I4 is carried on the outer end of a screw I5 which is free to rotate relative thereto. This screw is threaded through a portion of the member I I. Rotation of the screw by means of a knurled nut I6 will cause the member I4 to move towards and away from the member I3. In order to prevent rotation of member I4 relative to member I3, the member I4 is provided with a pin I'I which projects into and slides within a bore I8 provided in the member I I. Thus, with this structure the attachment may be clamped to or released from the portion I2.

The end of the section 6 of the telescoping rod is attached to a small metal plate I9 by means of suitable lock nuts threaded on the end of member The plate I9 is perpendicular to the rod. This plate I9 is connected by a compound hinge structure 23 to the solar shield 2I which I provide. The compound hinge structure embodies a leaf 22 hinged to the inner edge of plate I9 at 23 and to the edge of a second leaf 24 as at 25. The opposite edge of the leaf 24 is hinged to one edge of the shield 2 I as at 26. The shield 2I has secured thereto in spaced parallel relationship a screen 2l, whichI is of greater area than the shield. The shield 2I and the screen 2l are attached tc each other by means of the four pins 28. It will be noted that these pins extend from the screen through the shield and project from the opposite side thereof as indicated at 29. These pins are -perpendicular to the screen and the shield.

In positioning my attachment on the transit, it is clamped in such a position that the telescoping rod is in the same plane as the axis of the telescope of the transit. The shield 2I is so disposed that it is spaced behind the eyepiece 2a of the telescope a proper distance to obtain the desired size of the suns image focused by the Atelescope on the shield. The size of the image may be Varied by changing the length of the telescoping rod.` By means of the compound hinge structure 24, the shield 2| may be so positioned that the axis of the telescope 2 will pass through the center thereof and the shield will be perpendicular to said axis. The projecting portions 29 of the pins 28 will indicate whether or not the shield 2| is perpendicular to the axis of the telescope when the telescope is pointed at the sun. As indicated in Figure 9 when the shield is perpendicular to the axis, no shadow will be cast on the surface of the shield by each of the projecting portions 29 of the pins. However, as indicated in Figure 10, when the shield is not perpendicular' to the axis, a shadow will be cast on the surface of the shield by each of the projecting portions 29 of the pins 28.

The shield 2I may be made of metal or of any other suitable opaque material. The shape of the shield is illustrated best in Figure 8. It has an X-shaped centrally disposed slot 30 formed therein, the arms 3| of which are disposed at right angles to each other. The outer end of each of the arms 3| of the slot is pointed as indicated at 32. On each of its edges a notch 33 is formed in the shield. These notches have side` edges which are at right angles to eachother and which converge at a point 34. Each point 34 is in'alignment with a point 35 formed where the adjacent arms 3| of the slot converge.` All of the points 32 and 34 are located on the same circle. As will appear later, the points 34 provide a plurality of points uniformly disposed about the axis of the telescope with which the edge of the image of the sun may be aligned in order to take a solar observation. All edges of the shield are beveled to form knife edges 36 to prevent blurring of the shadow cast by the shield on the screen 21. In using the transit with my attachment positioned thereon, as indicated, the transit is so disposed that the object end 2b points at the sun. The circular image 36a of the sun (Figure 2) will be focused on the top surface of the shield 2|. The shadow Zla oi' the shield 2l will be cast on the screen 21, as indicated. The bright rays from the image of the sun will, under some conditions, pass through the X-shaped slot 30 and the notches 33 producing the respective `coniigurations thereof on the screen in bright outline as indicated at 30a. and 34a. The shadow 2c of the hair-lines of the instrument will also appear on the screen and will be in line with points 35a. When they are in line with points 35a, this will indicate that the center of the shield is at the axis of the telescope.

As previously indicated, in order lto take a'solar observation with my device it is desirable to align the edge of the image 35a. of the sun with at least three of the points 34. In making solar observations with my device, it is merely necessary to adjust the telescope 2 of the instrument in a vertical and a horizontal plane until the edges of the suns image 35a, is located exactly at the points 34 on the shield which will be indicated when a very small point of light from the suns image shows at the points 34a and no shadow shows at the points 32a, as indicated in Figure 5 which shows the shadow 2 la of the shield on the screen.

en the suns image is located so that the results illustrated in Figure 5 are obtained, the observation can be taken. The shield is preferably positioned at such a distance from the eye piece of the telescope that the diameter of the suns image will be slightly greater than the distance between the points 34a of opposite notches.

The solar observations may be quickly and easily made by iirst adjusting the telescope 2 in a vertical plane until the image 36a or the sun is at the proper vertical position on the Screen, as indicated in Figure 4, but the image will be too far to the left to register with the points 34a which will be indicated by the shadows at the two points 32a to the right. Then, d-ue to the movement of sun, the image will drift to the right from the position indicated in Figure 4 to the position indicated in Figure 5. At this instant, vertical and horizontal angle readings can be taken on the scales of the instrument. The suns image will continue to drift to the right out of coincidence with the points 34a, as indicated in Figure 6. In Figure 7 the conditions are shown such as will be encountered when the suns image is not in the correct vertical position which will be indicated by the shadows at the two lower points 32a.

Thus, with my device at least three points are provided which are uniformly spaced aboutY the axis of the telescope and with which the edge of Ythe image of the sun may be aligned and lat diiTerent color.

circle.

'the'speed of the horizontal and vertical move-- ment of the sun Acan be determined before and in a highly accurate and quick manner.

thatinstant the necessary readings may be taken on the transit. It will be a very simple matter to bring-the instrument into proper adjustment Where the edge of the image will align with the proper points.

It is not absolutely necessary to employ the screen 27. The screen may be dispensed with and the shield 2 I` only may be used. In using the shield only, the image of the sun can be brought into alignment with the points 34 on the shield. The image will be bright enough to show on the shield itself.

In Figure 11 I illustrate a shield which may be usedwithout a screen. I In this instance the shield has a main portion 2lb of a suitable color and portions 3319 and 30h, corresponding to the notches 33 and slot 33 of the shield 2l, which are of a With this structure the image of the sun should be brought into alignment with the points 34h. This shield will be used substantially as the shield 2|.

In using my device to determine the direction of a line, for example line (AB) of Figure l2, which might be a bridge, the instrument isset at the point (A). cites across the bridge to the opposite side to the point (B). The Vernier of the horizontal circle von the transit hasbeen set at O and the lower 'motion of the transit is clamped. My attachment is then positioned properly on the transit and solar observations are taken in the manner illustrated in Figure 12. These observations are Then the engineer or surveyor? taken by pointing telescope 2 at the sun and aligning the suns image with at least three of the peints 34 of the shield 2|, as previously*- verse position in the usual manner in order tof avoid errors due to inadjustments in the transit. Each time an observation is taken, the horizontal and the vertical angles are read on the instrument and are recorded in the table as indicated. It will be-noted that in the table there is provided columns for the time, the rate of horizon tal movement of the sun, the horizontal circle, the rate of vertical movement, and the vertical It'will also be noted from the table that vthe suns image to move into a position where the opposite edge of the image is in alignment with the points 34. In other words, the sun is-y permitted to move through its semi-diameter and the time this takes is noted. The vertical speed can be determined in a similar manner.

The average of the vertical angle is then used inthe reduction formula illustrated in the table` to determine the azimuth of the sun which will be the imaginary line (AC). The average of the "horizontal component found by the observations then subtracted from the azimuth of the sun which will give the azimuth of the line (AB).-v It is apparent from the above description that `I provided av device for obtaining solar observations by which the observations may be obtained My deviceis-such'that `the method lof taking solar ob- To do this it is merely nec-l servations is greatly simplified as compared to the ordinary methods of making solar observations. The pointings are taken directly and accurately on the center of the sun. The shield which I provide for use with a screen is of such a nature that it blanks out most of the suns bright image thereby obtaining the proper contrast of light. It accentuates the three or more points of light which are used in the pointings on the sun. It requires much less time in taking the pointings than with the ordinary methods and assures more accurate pointings. It provides a means to accurately measure the speed of the sun both horizontally and vertically. It gives actual progressive recordings of horizontal and vertical angles so that these angles can be checked by the rate of travel of the sun.

Many other advantages will be apparent from the preceding description, the drawings and the following claims.

By the term transit in the following claims I also intend to cover a theodolite or other similar instrument.

Having thus described my invention, what I claim is:

l. An attachment for an engineers transit comprising a shield member, means for supporting said member on the transit for movement with the telescope thereof, said member being spaced from the eye piece of the telescope along the optical axis thereof and being disposed substantially perpendicular to said axis, said member having at least three observable points thereon disposed along a circle which normally has its center at said axis and with which the periphery of the suns image may be brought into registry when the telescope is pointed at Vthe sun by adjustment of the angular position of the telescope.

2. An attachment for an engineers transit comprising a shield, means for supporting said shield on the transit for movement with the telescope thereof, said shield being spaced from the eye piece of the telescope along the optical axis thereof and being disposed substantially perpendicular to said axis, a screen attached to the shield and disposed substantially parallel thereto at a point spaced farther from said eye piece, said shield having openings therein so arranged that a shadow with at least three observable points disposed along a circle which normally has its center at said axis is formed on the screen with which the periphery of the suns image may be brought into registry when the telescope is pointed at the sun by adjustment of the angular position of the telescope.

3. An attachment for an engineers transit comprising a shield member, means for supporting said member on the transit for movement with the telescope thereof, said member having a fiat surface spaced from the eye piece of the telescope along the optical axis thereof and being adapted to be disposed substantially perpendicular to said axis, said member being so mounted that it may be adjusted axially of the telescope and transversely thereof, said member having at least three observable points thereon disposed along a circle which normally has its center at said axis and with which the periphery of the suns image may be brought into registry when the telescope is pointed at the sun by adjustment of the angular position of the telescope.

4. An attachment for an engineers transit comprising a shield, means for supporting said shield on the transit for movement with the telescope thereof, said shield being spaced from the eye piece of the telescope along the optical axis thereof and being disposed substantially perpendicular to said axis, said shield being opaque but having notches cut into the periphery thereof, said shield also having slots formed therein, the vertices of the notches and the pointed ends of the alternating slots all being equally spaced on the same circle with a center normally lying in the axis of the telescope and in such a manner that the periphery of the suns image may be brought into registry with such points when the telescope is pointed at the sun by adjustment of the angular position of the telescope.

5. An attachment for an engineers transit comprising a shield, means for supporting said shield on the transit for mov-ement with the telescope thereof, said shield being spaced from the eye piece of the telescope along the optical axis thereof and being disposed substantially perpendicular to said axis, said shield being opaque and being substantially square, said shield having V-shaped notches cut into the side edges thereof, said shield also having an X-shaped slot cut therein, the ends of said slot being V-shaped, the vertices of the notches and the vertices of the ends of the slots all being equally spaced on the same circle with a center normally lying in the axis of the telescope in such a manner that the periphery of the suns image may be brought into,

comprising a shield, means for supporting said` shield on the transit for movement with the telescope thereof, said shield being spaced from the eye piece of the telescope along the optical axis thereof and being disposed substantially perpendicular to said axis, said shield being opaque and being substantially square, said shield having V shaped notches cut into the side edges thereof, said shield having an X-shaped slot out therein, the ends of said slot being V-shaped, the vertices of the notches and the vertices of the ends of the slots all being equally spaced on the same circle with a center normally lying in the axis of the telescope in such a manner that the periphery of the suns image may be brought into registry with such points when the telescope is pointed at the sun by adjustment of the angular position of the telescope, and a screen attached to the shield and disposed substantially parallel thereto so that a shadow produced by the screen will appear thereon.

7. An attachment for an engineers transit comprising a shield, means for supporting said shield on the transit for movement with the telescope thereof, said shield being spaced from the eye piece of the telescope along the optical axis thereof, said shield being mounted on the transit in such a manner that it may be angularly adjusted relative to said axis, said shield having at least three observable points thereon disposed along a circle which normally has its center at said axis and with which the periphery of the suns image may be brought into registry when the telescope is pointed at the sun, said shield having pins disposed perpendicular to the surface thereof disposed towards the eye piece of the telescope to indicate whether or not said shield is perpendicular to the axis of the telescope.

8. An attachment for an engineers transit comprising a shield having observable points thereon with which the suns image is adapted to register when the transit is pointed at the the telescope in spaced relationship to the eyepiece thereof, and a compound hinge structure for connecting said shield to the rod which permits adjustment of the shield transversely of the longitudinal axis and angularly relative to said 5 axis.

CLAUDE H. WALL.

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