US2269896A - Slotted map templet - Google Patents

Description

Jan. 13, 1942. A. J. KRAMER SLOTTED MAP TEMPLET 7 Filed Oct. 22, 1940 Zinnentor Patented Jan. 13, 1942 i'l'E STATES FATE OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 379 O. G. 757) 4 Claims.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to graphic radial triangulation, and more particularly to the method of making maps from aerial photographs by the method generally known as the slotted templet method, disclosed in United States Patent No. 2,102,612, granted December 21, 1937.

The slotted templet method requires the use of templets, each of which is representative of the map area of one of a series of overlapping aerial photographs. Each templet has an aperture at the center of the area and radial slots defining the central angles of the map area corresponding to selected reference points. The templets are used by assembling them on a control surface in the sequence of the corresponding photographs, and they are connected with conjoining posts operating in the slots and the central apertures of the templets. Each post represents a selected reference point common to two or more templets. 'When the templets are assembled in this manner, the assembly can theoretically be extended and contracted in coordi-, nation to fit a particular condition established by basic control points, which are included among the selected reference points. However, under the present practice such a condition of coordinated extension and contraction is accomplished with great difficulty, and where a large number of templet units are employed, it is practically impossible to extend and contract the assembly in accordance with the theory of the method because of the great amount of friction between the posts and the edges of the slots. Also, certain stresses are set up in the templets which force the posts laterally against the edges of the slots. Since the templets are generally made of cardboard or bristol-board, in order to hold the cost of using the method down to a practical limit, the edges of the slots yield under the stresses, causing indentations which result in the conjoining posts being thrown out of the position which they should theoretically assume.

This, of course, makes the use of the method inaccurate.

The object of this invention is to obviate these difliculties by a simple and efiicient means to the end that the friction between the slots of the templets and the conjoining posts is reduced to a minimum, and damage of the edges of the slots is eliminated entirely, while permitting the use of such inexpensive materials as cardboard or bristol-board in making the templets. As a matter of fact, this invention permits the use of softer and cheaper grades of cardboard in making the templet as contrasted with the present practice of using expensive grades of cardboard and bristol-board with glazed or Waxed surfaces. This invention not only eliminates practically all of the friction between the conjoining posts and the edges of the slots of the templets, but also the friction between the faces of the templets which has also been found to be undesirable and to seriously affect the results obtained.

In general, I accomplish the objectives of my invention by providing the edges of each slot of the templets withan anti-friction surface. Several embodiments of my invention are illustrated in the accompanying drawing in which:

Figure 1 is a plan view showing a number of templets assembled on a mounting board, the slots of which are provided with anti-friction surfaces in accordance with one embodiment of my invention;

Figure 2 is an enlarged fragmentary sectional View taken along the line 22 of Figure 1;

Figure 3 is a plan View of a fragment of a templet showing the second embodiment of my invention; and

Figure 4 is an isometric view of a device embracing the third and preferred embodiment of my invention.

Referring to the drawing, and more particularly to Figures 1 and 2, the embodiment is illustrated in connection with a mounting board 10 and templets II, I2, and I3 placed on a sheet of paper M on the mounting board H3. Each templet, as it is customary, is provided with a central aperture l5 representing the center of the map area defined by the templet and with a plurality of radial slots I6 defining the central angles of the map area. In accordance with my invention, each slot I6 is provided with a thin grommet or eyelet I1, which is held in place by flanges l8 and I9, pressed together against the opposite faces of the templet. The grommets i! may be of any suitable anti-friction material, such as steel, aluminum, copper, or a metallic alloy. Suitable plated materials, such as nickel plated steel, can also be used. The sides of the grommets contact the conjoining posts 2|], which are generally of metal. These two metallic surfaces contacting each other reduce friction to a minimum, permitting the templets to move with ease relative to one another. Also, the adjacent flanges I8 and I9 of the overlapping grommets provide anti-friction contacts between overlapping templets, as shown in Figure 2. These grommets may be set in the slots in any suitable manner, such as by inserting halfway in the slot the grommet as a short preformed tube and outwardly flanging the projecting edges thereof on both faces of the templet. Obviously the grommets can be prefabricated with one side already flanged so that after inserting it into the slot, it is only necessary to flange the opposite side, in much the same manner as circular eyelets commonly used to secure sheets of paper together.

In order to provide a more economical means for providing an anti-friction surface on the edges of the slots, the embodiment illustrated in Figure 3 may be employed which consists simply of two independent members 2| and 22 of U- section, disposed over the opposite edges of each slot 23. This is the simplest embodiment and is as satisfactory as the embodiment illustrated in Figures 1 and 2, insofar as operation is concerned, because it is generally unnecessary to reenforce the ends of the slots, since the conjoining posts normally operate along the straight portions of the slot between the ends. The members 2! and 22 can be prefabricated to the desired shape and size and simply inserted in place. The conjoining post 24, which is subsequently placed between them, will hold them in position without the necessity of clamping the flanges against the faces of the templets. However, if desired, the inner surfaces may be roughened to increase friction and thereby avoid slippage. These strips are easily removed, and consequently they can be reused.

The preferred embodiment of my invention, il-, lustrated in Figure 4, is a modification of the embodiment illustrated in Figure 3, whereby the two strips 2| and 22 are resiliently connected. As illustrated, the embodiment comprises a strip 25 of a resilient metal, such as spring steel, in the general shape of a hairpin to conform to the sides and one end of the slot. The straight portions of the strip are provided with outwardly extending flanges 26 and 21, the slot 28 between the flanges being just wide enough to accommodate the thickness of the templet. To use this embodiment, the arms are pressed together against the resilient action of the material, inserted in the slot, and then released, the while guiding the edges of the slots between the flanges 26 and 21. The resilient action of the metal holds the device in position. This embodiment also is removable and reusable. It is removed by simply pressing the arms together and removing the device in the manner opposite from that in which it was inserted.

Having thus described my invention, I claim:

1. An article of manufacture comprising a U-' V shaped member resilient at the closed end, the

longitudinal edges of the arms thereof being outwardly flanged, said article being adapted to be inserted in the slots of map templets.

2. In a templet representative of a map area having radial slots therein defining the central angles of said map area, and conjoining posts adapted to be passed through said slots to adjustably connect said templet to adjoining templets of similar character, antifriction means having surfaces disposed between each post and its adjacent slot edges, said means having a total thickness greater than that of the templets and extending over the surfaces of the templet to contact similar means of said adjoining templets.

3. In a plurality of overlapping map templets of the type mentioned having radial slots in each templet defining outlying points and posts conjoining said templets through said slots, antifriction means comprising grommets disposed in said slots between the edges thereof and the conjoining posts, said grommets having a total thickness greater than that of the templets and flanges slidably engaging the flanges of like grommets in adjacent slots and supporting the templets in spaced relation about the posts.

4. In a plurality of overlapping map templets of the type mentioned having radial slots in each templet defining outlying points and posts conjoining said templets through said slots, antifriction means comprising strips having a U- shaped section removably disposed about the longitudinal edges of each slot, said strips being held in position by said posts, said strips having a total thickness greater than that of the templets, the flanges of said strips slidably contacting the flanges of like strips in adjacent slots and supporting the templets in spaced relation about the posts.

ALBERT J. KRAMER.

Images