US22876A - Marshal ingersoll - Google Patents

Description

M. INGERSOLL.

- Surveying Instrument.

Patented Feb. 8, 1859.

UNITED STATES PATENT OFFICE.

MARSHAL INGERSOLL, OF GRAFTON, OHIO.

SURVEYING INSTRUMENT FOR- DETERMINING INACCESSIBLE HEIGHTS AND DISTANCES.

Specification of Letters Patent No. 22,876, dated February 8, 1859.

To all whomit may concern:

Be it known that I, MARSHAL INonnsoLL, of Grafton, in the county of Lorain and State of Ohio, have invented new and useful Improvements in Surveying Instruments; and I do hereby declare that the following is a full and complete description of the construction and operation of the same, reference being had to the accompanying drawings, making part of this specification.

The nature of my invention consists in such a construction and arrangement of devices, that the exact distance of an object may be determined from the point at which the observation is made, Without the proc ess of chaining, as is now usually practiced; and also of determining by a similar means the altitude of objects, by simply knowing their horizontal distance from the point of observation.

My improvement consists of two parts: namely, the instrument of observation, and the target, and these are used in connection with each other, andare accompanied by a table of calculation, a reference to which will give any distance or altitude required.

Figure 1, is a side view of the instrument of observation, that is, for taking dis tances and altitudes. Fig. 2, is a view of the opposite side of the same instrument. Fig. 3, is a top view of the same. Fig. 4, is a front end view, and Fig. 5, is a back end view. Fig. 6, is a front viewof the target. Fig. 7, is a topview of the same.

Like letters refer to like parts.

The instrument is mounted upon a staff or tripod, represented at A, in Figs. 1, 2, 4 and Its attachment is by aball and socket, B or its equivalent; A rectangular plate O is mounted horizontally above the ball and socket joint. Near the center of this plate, and below the surface, is placed a spirit level I), lengthwise of the plate O. Another spirit level may be placed at right angles to this. By means of these, the plate O can be adjusted to a horizontal position. The graduated limb of a compass, with a polaric needle, may be placed upon the plate O, and concentric with the axis of the ball and socket. The spirit levels may be both placed within the limb of the compass. A telescope may also be mounted above the compass limb, as is the case in a transit instrument. A slit sight E, Figs. 1, 2, 3 and 4, is mounted upon the front end of the plate C. If a telescope is used, the eye piece of the same occupies the same position. The telescope should be rigidly mounted upon or above the plate O and parallel thereto. Upon the end of the plate O, opposite to the sight E, is placed a stationary hair sight F, Figs. 1, 2, 3 and 5. A line drawn through the center of this, and the slit sight E, forms a line parallel with the edge of the plate The vertical slit in the sight E, and the vertical hair, in the sight F, should coincide in position. An adjustable vertical hair sight G, is mounted upon sliding ways H, placed transversely to the plate O, and a little forward of the sight F. The sights G and F are constructed in the manner shown in detached sect-ion G and F, the hairs having but one metallic support, and being attached to a projection as shown in the figure, F and G, the open sides of the supports facing each other, so that the hair in the sight G can be made to occupy a position upon an exact line with the stationary slit sight E and stationary hair sight F, and to move toward the lefthand, without obstruction to the vision from any intervening object. Thus, when the eye is placed to the slit sight E, the hair-sight G can be adjusted, so that it will exactly coincide with the hair sight F and slit sight E, and the two can be separated by moving the sight G toward the left the smallest fraction of an inch, and to any extent beyond, within the limits of the instrument.

The hair sight G, is moved upon the ways H, by means of a very fine screw I, Figs. 3 and 5, the head of which is flattened for convenience of turning the same, with the thumb and finger, as seen at I Figs. 3, 4 and 5, or it may have a common milled head, which will answer the same purpose. Between the head of this screw and the plate G is placed an index plate J, through the center of which passes the screw I. An index finger K, Fig. 1, is attached to the screw I. The index plate is divided into any number of divisions corresponding to the lead of the screw I; for example, if the screw requires to be turned once around to move the adjustable sight G, one sixtieth of an inch, then the screw thread has a lead of of an inch, and the dial plate J should be divided into sixty equal parts. A vernier scale is also placed at the base of the adjustable hair sight Gr, having the same scale as the index plate. Now, it follows that if the slit sight E and the hair sight F are placed just twelve inches apart, and the hair sight G adjusted to one sixtieth (5 of an inch, at the distance of twenty four inches a target should be spread to the distance of two sixtieths of an inch, or double the distance of the base line F, G, and so on, at the ratio of the square of the distance for any length observed. Now, by a simple mathematical calculation, or what is more convenient, by reference to tables previously calculated, and within the range of practical observation, by the known divergence of the lines E F and E G, the exact distance of any object can be accurately determined.

In graduating the Vernier scale upon the sliding way H, so as to-compensate for the error consequent upon the sight Gr being in a different plane from the sight F, a line should be drawn from the center of the sight F toward the left, and at right angles to a line extending from E to F. The true scale should first be set off upon the line thus drawn from the sight F, and the graduations upon the Vernier made by drawing lines from each of these divisions to the center of the sight E, where it intersects the face of the plate G. The point where said lines cut the vernier will read the corrected distance. Or this correction may be avoided by such a construction and arrangement of the sight F as to bring it into the exact plane of the moving sight G, in which case the Vernier would need no corrected scale. Accurate observations can thus be made. For the purpose of accomplishing this object, I construct a target shown in Figs. 6 and 7 which or its equivalent should be used. This consists of a staff L, about four feet in length, at the top of which is placed a horizontal scale M, which has upon its face divisions corresponding to those upon the index plate J and the Vernier scale of the adjustable sight G.

Now in using this instrument the sight G is set at a definite and known distance from the sight F; the target bearer places the target at any desired distance and adjusts the target N, by means of signals from the engineer, so that it will be in an exact range with the sights E and F; then the target 0 is in like manner adjusted upon the graduated scale M until it is upon a line with the sights E, G. If then the figure at which it stands upon the scale M is compared in the table of calculations, with the figure upon the index J, or the distance the sights F G are apart, the table will show the exact distance of the target from the instrument.

In taking altitudes, I provide a graduated scale, P, which is attached in a vertical position to the plate 0, opposite to the index J. A straight arm Q is attached to the plate C, at a point opposite the sight E, by a pin upon which it articulates. The free end of this arm is held in contact with the scale P by a guard R and can be elevated above or depressed below the plate C. Sights can be placed upon this arm, through which an observation can be taken, or for long distances a telescope can be mounted thereon. The distance of an elevation having been determined, and the arm Q adjusted to the elevation or depression required, the reading upon the scale P when compared with the prepared table, will give the altitude of the object.

By placing two instruments side by side and about a foot from each other, (or at any definite and calculated distance), but so varied in form that the sights G both adjust inward, a system of triangulation can be established, and the distance of observed points accurately determined, without the use of a target.

lVhat I claim as my invention and desire to secure by Letters Patent, is

1. The construction of a surveying instrument, for taking distances and altitudes, upon the general principle set forth in the foregoing description and specification.

2. I claim especially, the arrangement of the three sights E, F, G, or their telescopic equivalents, one of which is adjustable upon a scale, by which means, and the adjustment of a target having the same horizontal scale, the distance of any object within the range of vision can be determined. In this claim, I do not intendto confine myself to the precise arrangement herein set forth, but to use a telescope in which a similar adjustment of hair sights, (or filaments of silk) are provided for upon a definite scale, as herein set forth. Neither do I intend to confine myself to any particular scale, but to ado-pt a decimal scale, or any other that I may see fit.

3. I also claim especially a horizontal target, having marked upon it a scale corresponding to that of the accompanying instrument, which target is to be used in connection therewith as herein described, the same forming a part of my invention.

4. I further claim the scale of altitude in MARSHAL INGERSOLL.

lVitnesses I. BRAINERD, W. II.- BURRIDGE,

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