US2232319A - Stadia protractor - Google Patents

Description

Feb. 18, 1941. E, GAY 2,232,319

swan. Pno'fmc'roR Filed Oct. 12,1939

////MMIII Patented set. s, 1941 2,232,319

UNITED" STATES PATENT; OFFICE WZZZTZZLKZZZ; Y. App cation :31 No. 299,209

This invention relates to an improved stadia mounts the slide plate with respect to the graduprotractor and seeks, among other objects, to proated' plate. As will be seen in Figure 3, the slide vide a device 01 this character which will be plate II is of slightly less radius, or length, effective for permitting the measuring of vertical than the plate I, so that the pointer IE will be 5 and horizontal distances when the transit is not permitted to coperate with the scales I and I. 5 equipped with an attachment for permittingdi- The matter of laying of! the plates I and III rect reading of such distances. will now be set forth in more detail.

Another object of the invention is to provide As will be seen in Figure 1 of the drawing,

a stadia protractor which will comprise a pair of the arcuate edge 2 of the graduated plate I is swingingly engageable sector shaped plates on provided with the scales 6 and I, the scale 6 10 which are placed indicia for permitting the readbeing laid oii in degrees. The side edge 4 deing of vertical and horizontal distances. fines a base for the squares 8. As will be seen A further object of the invention is to provide at I8, the upper edge of the side edges 3 and I2 a stadia protractor which is characterized by are deflected near the arcuate edges 2 and II,

the utmost simplicity and which will greatly respectively, the purpose of whichwillbebrought 15 minimize the amount of calculation required to out hereinafter. On the scale, located on the obtain horizontal and vertical distances in a base side 4 of the plate I, two inches represent.

stadia survey. one hundred feet in the field onwhich the sur-- Further objects of the invention will appear veyis-being made, or one hundredone-hundredths as the description proceeds. of a foot, which is to say, one foot on the vertical 20 In the drawing: rod which is normally held in front of the transit Figure 1 is a plan view of the graduated plate during e m king or a survey- The o ch employed, squares I are sub-divided into the squares 9 which Figure 2 is a plan view of the slide plate, and have sides equivalent to ten feet in the field. The Figure 3 is a plan view showing the slide plate squares 9 should be further sub-divided to meas- 25 and graduated plate as they would appear in ure to'one foot in the field. In order to facilioperative position. tate reading, the hundred, ten and five foot lines Referring now to the drawing, the numeral I are more heavily marked. indicates in general the graduated plate. The With further reference to the slide plate I0, graduated plate I is of sector shaped contour and the parallel lines I6 are not intended for measuris provided with an arcuate edge 2 and converging but to serve as transversals with reference ing side edges 3 and 4 which meet at the apex 5. to the graduation on the plate I. They would The side edges 3 and 4 are graduated from the pro a y be spa d at r ular nterva s ran in apex toward the arcuate edge and said arcuate from three one-hundredths to one-tenth inch edge is provided with scales 6 and I. The plate with every third one marked in heavier lines to r I is laid out throughout the major portion of its facilitate reading. arc and between the edges 3 and 4 and the scale The manner of using my improved stadia pro- 6 with relatively large squares l which are subtractor will now be described. Let it be supdivided into a. group of smaller squares 9. posed that the stadia shot to be reduced is a 40 Mounted to slide over the face of the graduated rod reading of 510 with a vertical angle of either plate I is a transparent slide plate ll which is plus or minus of twenty-three degrees. The slide 40 of substantially sector shape. The slide plate It plate In is swung about the pivot bolt and in the has an arcuate edge I I and side edges I2 and I3 slot II to the position where the pointer I5 overwhich converge at the apex I 4. The side edge I2 lies the twenty-three degree mark on the scale is projected past the arcuate edge II to define a i 01' the plate I. In this position, one of the pointer I5 which, as best seen in Figure 3, is parallel lines I6 will be in overlying relation to adapted to cooperate with the scales 6 and "I. or near the 510 mark on thebase or slope line The slide plate ll is provided, throughout the of the plate I.- As previously explained, the slope major portion of its area with parallel lines I6 line is defined by the upper edge of the side my. which are perpendicular to the side edge I2. tion 4 of the plate I. By moving the slide plate, 50

In order to connect the plates I and III, a bolt 0! course, one of the parallel lines of the slide is employed. This bolt extends through the plate may be brought directly over the 510 mark, apices 5 and I4 at the meeting point of the ii! itis not already inthispositlon. If astraight inner edges of the side edges oi both of the plates edge or other object is held adjacent the edge I8, and throu h a slot The slot II s dably the slide can be moved without shifting the slide 55 from the twenty-three degree mark on which it is set. Attention is called to the fact that it is for this purpose that the edge I I is provided. The parallel which is to overlie the 510 mark is a significant transversal for this particular measuring operation. Its intersection at the 510 mark in a slope intersection. The next step necessary is to follow the significant transversal to the intersection with the pointer line which is, of course, the critical intersection. At this point both the vertical and horizontal distances may be read. In the example given, estimating between lines, we read 442 for the horizontal distance and 153 for the vertical. In checking against stadia tables, it will be noted that the answers given are 432.1 and 183.45.

The slot ll on the slide plate ll will cover on the scale what corresponds to fifteen feet, approximately, in the field. Inasmuch as stadia is not used for measurements that are close to the instrument, this will be of no importance.

Where rod readings are greater than the scale range of the protractor, the manner of reading distances is as follows: For example, let it be supposed that the rod reading is 840, the angle 2:. With the protractor, the pointer is kept at angle 1:. Then obtain a horizontal and vertical distance for a 500 reading and add horizontal and vertical distances for a 340 reading. In order to correct for the discrepancy within the telescope, add horizontal and vertical reductions of the instrument constant. Horizontals are, of course, to be added to horizontals, and verticals are to be added to verticals.

It is believed that the operation and construction of my improved stadia protractor will now be understood.

Having thus described the invention, what is claimed as new is:

1. In a stadia protractor, a graduated plate of sector shape having graduated side edges and being laid oil in squares, said graduated plate having an arcuate edge formed with scales, a slide plate having a pointer at one edge and having a plurality of parallel lines thereon, said lines being perpendicular to the pointer, and means pivotally connecting the slide plate with the graduated plate, the scales and squares on the graduated plate cooperating with the pointer and certain of the parallel lines for permitting reading of stadia distances from a rod reading and a vertical angle, said means permitting limited shifting nioitrement of the slide plate on the graduated p a e.

2. In a stadia protractor, a graduated plate of sector shape having side edges converging to an apex and having an arcuate edge provided with scales, one of the side edges defining a slope line, said graduated plate having its inner area laid out in squares, the slope line providing a base for certain oi said squares, a slide plate oi sector shape and of transparent material, said slide plate having an arcute edge and having side portlons converging to an apex, one of said side portions being projected to define a pointer and having its edge near the arcuate edge deflected to lie parallel with the inner edge of the pointer, said slide plate having parallel lines throughout its inner area, said lines being disposed perpendicular to the pointer, and a bolt extending through the apices of the plates and pivotally connecting them for relative slidable movement, said pointer and parallel lines cooperating with the squares and scale for permitting reading of vertical and horirontal stadia distances from a given rod reading and angle of inclination.

3. In a stadia protractor as recited in claim 2, wherein the slide plate is provided with a slot for permitting longitudinal shifting movement of said slide plate relative to the graduated plate.

ELBERT E. GAY.

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