Abstract:
A device for use in plotting equal spacings over a distance includes a frame comprising opposed first and second pairs of frame members with each frame member having opposed ends and pivotal connecting means for pivotally connecting adjacent frame members at respective ends thereof. Each of the first pair of frame members includes a plurality of longitudinally spaced-apart apertures disposed along its respective length. The device further includes a flexible linear member placed continuously through the apertures of said first pair of frame members to provide a plurality of parallel equally spaced apart linear elements which are disposed in substantially parallel relation with each other and with the second pair of frame members, and a marker element being slidably attached to each of the plurality of linear elements.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a device for assisting a user to draw a topographical contour map, more particularly to devices for use in indicating equal spacings between two terminal points of a line or distance so that a topographical contour map may be accurately drawn therefrom. 
     BACKGROUND OF THE INVENTION 
     When using the stadia method (the plotting of points) of making a topographical contour map, engineers and surveyors have experienced difficulty in precisely drawing the lines or contours necessary to provide an accurate display of the topography of a finite parcel of land. In particular, the topographical lines are drawn based on a series of points plotted in generally a minimum of three directions. The plotted points each represent a certain elevational unit or elevation (e.g. 1 foot). Interpolation is necessary to precisely position the contour lines, especially when the total elevation requires a fraction of a unit. Although certain devices have been developed for the purpose of addressing the problem, the prior art devices are generally expensive, bulky, and difficult to use. 
     It would be of significant advance in the art of producing topographical contour maps to develop a device having a durable, compact construction and design which facilitates the positioning of points to enable the drawing of accurate, low-cost topographical contour maps. 
     SUMMARY OF THE INVENTION 
     The present invention is generally directed to a device for assisting a user in drawing a topographical contour map through the plotting of multipoints in multiple directions comprised of a frame including opposed first and second pairs of frame members where each of the frame members has ends that are pivotally connected to the ends of adjacent frame members so that the frame be readily moved to assume a variety of parallelogram shapes, and a plurality of equally spaced-apart linear elements extending between the first pair of frame members wherein the distance between the spaced apart elements changes as the shape of the parallelogram changes. The shape of the frame and therefore the distance between the linear elements may be adjusted to plot points for the formation of contour lines on a topographical contour map regardless of the steepness of the grade of elevation. The device enables the points to be plotted in a manner which is visually easy to read. The device is also portable with a durable construction. 
     In one aspect of the present invention there is provided a device for assisting in the formation of a topographical contour map which comprises: 
     a frame including opposed first and second pairs of frame members with each frame member having opposed ends; 
     pivotal connecting means for pivotally connecting adjacent frame members at respective ends thereof; and 
     a plurality of equally spaced-apart linear elements extending between the first pair of frame members with alternate linear elements being distinguishable from adjacent linear elements. 
     In another aspect of the present invention, the device comprises: 
     a frame including opposed first and second pairs of frame members with each frame member having opposed ends; 
     pivotal connecting means for pivotally connecting adjacent frame members at respective ends thereof; 
     a plurality of longitudinally spaced apart apertures disposed along the length of each of the first pair of frame members; 
     a single linear member being continuously placed through the apertures to provide a plurality of parallel equally spaced apart linear elements which are disposed in substantially parallel relation with each other and with the second pair of frame members; and 
     a marker element being slidably attached to each of the plurality of linear elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following drawings in which like reference characters indicate like parts are illustrative of embodiments of the invention and are not to be construed as limiting the invention as encompassed by the claims forming part of the application. 
     FIG. 1 is a top plan view of one embodiment of the device of the present invention, 
     FIG. 2 is a cross sectional view of the device taken along  2 — 2  in FIG. 1; and 
     FIG. 3 is a cross sectional view of the device taken along  3 — 3  in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is generally directed to a device for assisting the user in drawing a topographical contour map. The device is constructed in a manner that provides a simple and inexpensive tool for plotting points to facilitate the formation of topographical contour maps and other graphical representations. The device is easy to use and affords accurate plotting which enables the drawing of topographical contour maps which precisely depict the contour or elevation of a finite parcel of land. The device is portable and compact making it especially useful for engineers and surveyors working on-site under various lighting and weather conditions. In addition, the device may be constructed in a manner which allows the user to carry the device is the pocket. 
     Referring to FIG. 1, a device  10  is illustrated for one embodiment of the invention. The device  10  includes a frame  12  having a general parallelogram shape where the angles of the parallelogram can change as hereinafter described. The frame  12  has a pair of opposed generally shorter frame members  14  and  16  pivotally connected to another pair of opposed generally longer frame members  18  and  20  at their respective ends by a pivot assembly  22 . The frame members  14 ,  16 ,  18  and  20  and the pivot assemblies  22  may be constructed of any suitable durable, rigid material such as metal, wood, plastic, carbon composite, and the like, which can withstand the rigors of constant flexing and pivot movement. The frame members  18  and  20  further include a plurality of longitudinally spaced apart apertures  24  which are used to house and align linear members as hereinafter described. The plurality of spaced apart apertures  24  are axially aligned with the center of the adjacent pivot assemblies  22  between the frame members  14 ,  16 ,  18  and  20  of the frame  12 . 
     A single, flexible linear member  26  is threaded alternately between each member  18 ,  20  beginning at the endmost aperture and continuing successively through corresponding apertures  24  to provide a plurality of parallel equally spaced linear elements  28 . The linear member  26  may include, but is not limited to, thread, fiber, string, cord, wire made of metal, plastics, and the like. In this embodiment, the device  10  includes thirty-three linear elements  28  which are spaced apart by {fraction (3/16)} inch when the frame  12  is straight and squared. It will be understood that the number of and the distance between the linear elements  28  may be varied as desired by the modifying the number and spacing of the apertures  24  in the device  10 . 
     The opposite ends of the linear member  26  may be securely anchored by knots (not shown) which are larger than the diameter of the apertures  24 . It will be understood that other means for anchoring of the ends may be used. As shown in FIG. 1, one end of the linear member  26  is anchored on one member  20  and the other end of the linear member  26  is anchored on the other opposed member  18 . 
     It will be noted that, when each member  14 , 16 , 18 , 20  of the frame  12  is arranged in substantially right angular relation with an adjacent member, the spacing between the linear elements  28  is at its maximum. However, when adjacent frame members are shifted out of right angular relationship with respect to each other, the distance between the linear elements  28  will progressively decrease. 
     To divide a given distance or line into a number of equal spaces, the frame  12  of the device  10  is adjusted until the outermost two linear elements, which encompasses a number of linear elements therebetween, are in alignment with terminal points of the distance or line to be divided. Smaller spaces are obtained by partially closing the frame  12  or shifting the frame  12  so that adjacent frame members are progressively shifted away from right angular relation. Therefore, for example, if a line or a distance is to be divided by the device  10  into ten equal spaces, the spacing is accomplished by shifting the frame  12  until the outermost linear elements  28  encompassing nine linear elements  28  therebetween, are in alignment with the respective ends of the line. It will be understood that if a line or distance to be divided is greater than the distance between the two outermost linear elements  28  when the frame  12  is in its fully opened position, then the frame  12  may be shifted so that the linear elements  28  are shifted from a normal or perpendicular relation with respect to the frame members to a more angular position with these frame members. This reduces the spacing between adjacent linear elements to permit a larger number of linear elements  28  to be utilized in dividing the line or distance into equal increments. 
     As to using the device  10  for drawing topographical contour maps, a map indicated with a series of vertically and horizontally running grid lines may be utilized. However, it will be understood that maps without grid lines may also be used with the device  10 . Through known methods of surveying land, the user can determine the corresponding elevations at select points on the map, for example, at the points intersected by the grid lines. The user begins by selecting two neighboring known elevation points. Knowing the difference in elevation between the two elevation points, the user determines the number of linear elements  28  of device  10  needed for plotting one or more intermediate elevation points, for example, selecting one linear element  28  for each unit change in elevation. The frame  12  of the device  10  is then adjusted until the two outermost linear elements  28 , which encompasses the selected number of linear elements  28  therebetween, are respectively in alignment with the two known elevation points on the map. The user marks off the intermediate elevation points as indicated by each linear element  28 . The process is repeated throughout the grid or area of the map for plotting the intermediate elevation points. Upon completion, the user draws the contour lines through the associated elevation points as plotted. 
     Referring again to FIG. 1, each of the frame members  18  and  20 , further includes a sequence of numbered markings  30 , each of which corresponds to an associated aperture  24  and linear element  28 . The markings  30  provide a visually efficient way of counting off the number of linear elements  28  that the user may need to plot which provides better accuracy and speed. Rather than physically counting each linear element  28  which may introduce error and slow the plotting, the user simply glances at the desired number and then look to the linear element  28  immediate to the number marking  30 . 
     The plurality of linear elements  28  may further include alternate linear elements  28  being distinguishable from adjacent linear elements  28 . This effect may be accomplished by generating a visually distinctive scheme which alternates between each linear element  28 . Such visually distinctive schemes may include color coding each linear element  28  alternately between two contrasting colors, for example, providing the user with a facilitated means for visually pinpointing a specific linear element  28  during the plotting process. In a preferred embodiment, the plurality of linear elements  28  may include a red and white color scheme for providing improved visual distinguishment. It will be appreciated that other alternating visually distinctive schemes may be used as desired such as using different surface textures, translucence, visual patterns, and the like. 
     As shown in FIG. 1, all or some of the linear elements  28  may include a marker element  32  slidably connected thereto as shown specifically in FIG. 1 where a marker element  32  is provided on alternating linear elements  28 . The marker element  32  is configured to selectively slide along the length of the corresponding linear element  28 . The marker elements  28  of the outermost linear elements  28  may be positioned over the corresponding terminal points for better visibility and ease of use. The marker elements  28  provides the user with a rapid means for ensuring that the device  10  is correctly aligned with terminal points of the distance to be divided and that the correct number of linear elements  28  is apportioned thereto. 
     Referring to FIG. 2, a cross sectional view of the member  20  is shown. The edge portion  34  proximate to the apertures  24  is tapered for permitting the user to easily match the numbered markings  30  with the corresponding ends of the linear elements  28  from various perspective views. The opposed member  18  includes the same cross sectional profile as member  20 . 
     Referring to FIG. 3, a cross sectional view of the assembled frame members  16 ,  18  and  20  is shown with the plurality of linear elements  28  extending between the frame members  18  and  20 . The pivot assembly  22  comprises a machine screw  38  which extends through a washer  42  and an opening  36  in each of the associated frame members  14 ,  16 ,  18 , and  20 , and a wing nut  40  threadedly engaged with the machine screw  38 . The wing nuts  40  may be tightened to generate a frictional engagement of the contacting faces between each member  14 ,  16 ,  18 ,  20  and permit the device  10  to be remained in an adjusted position. Alternatively, a nut and bolt assembly may be used for the pivot assembly  22 . The coefficient friction of the suitable durable, rigid material employed permits the frame members to be retained in a selected position until forcibly shifted to a new position. However, the pivot assembly  22  is not limited to the arrangements described above and may include other mechanisms and devices which permit selective swivel movement between the frame members of the frame, as known to one of ordinary skill in the art. It is preferable to overlap the frame members  14  and  16  over the opposed pairs of frame members  18  and  20 , thereby minimizing the distance between the plurality of linear elements  28  and the plotting surface for better accuracy and precision. 
     The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.