US2327982A - Surveying instrument - Google Patents

Description

Aug. 31, 1943- D. c. JOHNSON 2,327,932

' SURVEYING INSTRUMENT Filed Sept. 2, 1942 2 Sheets-Sheet 1 Inventor 0. G. Johnson 8 D. c. JOHNSON I 2,327,982

SURVEYING INSTRUMENT Filed Sept. 2, 1942 2 Sheets-Sheet 2 YTT\ Fig.3

Inventor D. Gdahnson Y Patented Aug. 31,1943

2,327,982 SURVEYING INSTBI IME NT h DonaldQ. Johnson, BerkeleypCalif. Application September 2 1942, Serial 456,981 g 1 mm. (else-70y (Granted under the act of March 3, 1883, as t i amended April so, 1928; 379 o. G. 757) l This application is under the act of March 3,1883, as amended'by theact of April 30, szatand the invention herein described, if patented, may be manufacturedand used by or i l for the Government of theUnited States of Amer ice. for governmental purposes without. the pay-.

ment to me ofany royalty thereon.

This invention relates to; geometrical instrurnents andit .ismore particularly concerned with instrumentsuseful in surveying. j i 'lihe general object oi thisinvention is. the pro vision of meanswhich vln'll enable a person without the assistance of any other person tomake surveys in cases where a high degree of precision :is not required, such as in laying outfarm terraces, drainage lines, gradients, and so forth. i In theaccompanying drawings there is illustrated. an embodiment of this invention which is explained in the following description and considered. together a full understanding may be had by those skilled inthe. art.

t In the drawings:

Figure 1 is a side elevational view of a preferred embodiment. of the principal instrument of this invention.

Figure 2 is a side elevational view of the instrument illustrated in Figure 1. Figure 3 is a section along the line 3-3 of Figure 2 l Figure 4 is a front elevational view of a form of target rod of the invention. 1 i

Referring with more particularity to the draw-. ings in which like numerals: designate like parts, the principal instrument is mounted on .a rod ll of non-circular cross-section upon which a sleeve I2 is slidably disposed. The sleeve I2 is provided with a thumb screw clamp 13 for. fixing it at and 23 above the are ll by means fofwhich they can be pressed together :to clamp the arc in,

different positionsof rotation. A telescope 25 is securedtothe bottom of the arc II by means ofarms 26fand 21. Thi telescope has the usual eyepiece 211i and cross hairs 28 and, as incertain conventional forms oftelescopic levels is provided with anaperture 29 through the top of the casing Light entering through thi apertureis reflected to 'the eyepiece of the telescope by meansofa mirror 30 orother suitablereflector. Inconventional forms a spirit level is placed .onthe casing of the telescope over this aperture 50 that it canube observed through the eyepiece simultaneously with objects in the principal field of view of. the.v telescope.

sleeve l2 which pivotally carries radialarms l5 and III which are integral with a circular are H having delineated thereon an angular scale l8.. The arms 16 and ID are supported between an inner flange l9 and an outer flange 20 of the spindle l5. i i A vertical arm 2| is secured to the spindle I5 and terminates on the outer face of the are I! adjacent the scale l8 at which point it is'provided with a reference mark 22 for indicating relative positions of the are about the spindle. Another vertical arm 23 also secured to the spindle l5 terminates on the opposite face of the arc II. A thumb screw 24 engages the arms 2|.

However, in accordance with this invention a spirit level, designated by the numeral 3! is securedfon the flange 20, andthe telescope is so disposed that the aperture 29 is radially opposite the center of the bubble tube of the level .31, so that the bubble is not affected by the pivotal movement of the telescope and can be seen through the eyepiece 21A when the telescope is in different angular positions. The aperture 29 is covered with a window 32 of glass or other suitable material. l 1 v The bottom of the rod II is provided with a foot plate or shoe 33 to support the instrument over the ground and a spike 34 for fixing the rod tothe ground. The spike 34 is longitudinally carried by the bands 35 and 36 to tighten the spike in different positions against the rod. An aperture 4| i provided'in the shoe 33 through which the spike slides. i I

The target rod 42, illustrated in Figure 4, is substantially like the ordinary target rods, having a linear scale43 and an adjustabletarget 44, except that the bottom istprovided with a shoe 45 and spike 46 like that provided for the instrument rod l I. Similar means are also provided. for guiding and releasably securing the spike to the rod. l The rod II can be set on the ground and supported by forcing the spike 34 downward into the ground and clamping it withthe screws 39 and and dowel clamp 31. The rod. can be leveled while looking through the telescope in difierent angular positions, since the level bubble is reflected to the eye of the observer through the aperture 29. The target rod 42 can also be placed clamped. Withthe telescope on the instrument rod H set at the same elevation, the operator,

measures or paces off from the target rod the intervals at which he wishes to set stakes in the approximate direction on the grade desired. I He then sets the telescope at an angle corresponding to the grade desired and clamps it in position with the thumb screw 24. Withthe shoe 313 of the instrument rod resting on the ground at the first interval point and the rod II in a plumb position, the operator sights the telescope in the direction of the target MQthe while maintaining the instrument plumb by keeping centered the level buinhle'which he can see while sighting the telescope. The operator then notes how much the' horizont'al wire of the telescope misses the target and moves the instrument rod up or downhill as maybe necessary to correct for the error.

If greater accuracy is desired, the procedure may be repeated with less approximation. A stake, or other marker, is then driven in the ground at the finalpositicn of the instrument rod The same procedure is repeated for eachpoint at which itis desired to place a stake ormarker.

' determine the grade of an existing slope,

I both the target M on the target rod and the in-- strument on thei'nstrinnent rod 11 are set at the same vertical height.- "The target rod is then placed in a plumb position atone end of the slope is read on the scale is line and secured to the ground in the manner previously indicated. The instrument is then taken to the other end of the slope line Where the instrument rod isplaced in a plumb position. The operator then loosens the thumb screw 24 and pivots the telescope until he centers its horizontal cross hair on the target, the while manipulating the rod to keep it in a vertical position. The telescope is then'clamped by means of the thumb screw 24 and the vertical angle or slope opposite the reference mark 22; p

The above examples demonstrate the manner in which this invention can be used in some prisurveying operations and they are not in- Tasted position, a spindle fixed to said sleeve normal to said rod, '2. telescopeswingably supported on said spindle with its line otf lsight normal-to said spindle, a' spirit level secured tow-said spindle in a plane parallel to; the vertical plane through said line of sight, means projecting an image of said level'in the field of viewof said telescope in all angular positions of said telescope on said spindle, an angular scale concentric of said spindle and secured to said telescope, and means for clamping said scale and telescope to said spindle.

DONALD C. JOHNSON

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