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FIELD OF THE INVENTION 
     The invention relates to an apparatus for protecting stream banks, shorelines and other areas from erosion. 
     BACKGROUND OF THE INVENTION 
     In nature, wind and water can exert forces upon the earth&#39;s surface and carry away soil, rock and other materials. In addition, mankind&#39;s influence on the environment often exacerbates these natural erosion processes. For example, natural erosion can be accelerated by altering the course of a stream or removing foliage which would otherwise help anchor soil in place. 
     Soil erosion is a particular problem in areas such as riversides, stream banks, shorelines, beachfronts or other submersed areas. In these environments, the force created by flowing water current or crashing waves can, over time, carry away large amounts of earth and cause significant and costly damage to property. For example, erosion can destroy the integrity of the base of a stream bank, making it necessary to restabilize the area through an expensive process of filling and structural repair. Similarly, erosion, if not controlled, can cause valuable waterfront property to simply disappear. 
     Previous attempts to develop an effective, easy and efficient way of controlling erosion have not been successful. One such prior art attempt is the use of a solid wall to abut and protect the area in question. For example, a cement or log wall can be installed along the underwater base of a stream bank to prevent the stream from contacting, and thereby eroding, the bank. This approach, however, has numerous drawbacks. A solid wall is costly, difficult, and in some locations, impossible to install. Also, a wall is aesthetically not attractive. 
     A solid wall is also not environmentally attractive because it is not an effective method for controlling erosion. A solid wall does not dissipate the energy generated by the flow of water. Rather, water flowing along the wall will accelerate, thereby causing greater erosion to occur at those locations not protected by the wall, such as the stream or riverbed. Moreover, vegetation, which helps anchor soil and prevent further erosion from wind and rain, will not grow on a solid wall. 
     Some other prior art attempts to control erosion involve the use of interlocking units to help stabilize an area. In such systems, a trench is dug at the underwater base of the submersed area in question. One by one, the interlocking units are placed in a row within the trench to form a base for the protective cover. The remainder of the protective cover, or “revetment,” is formed by stacking additional rows of units upon the base row until the units cover the area to be protected. 
     Prior art erosion control systems that feature interlocking units suffer from a variety of drawbacks. The units are large, heavy and cumbersome, making the transportation and installation of the units burdensome and expensive. Also, because the units are interlocking, they overlap one another so that a large number of units are required to cover the area being protected. 
     In addition, because the units are not positively connected to one another, but merely interlock with or rest against one another, one or more of the units can shift independently of the other units along any of the three dimensions. This undermines their effectiveness at erosion control and, in turn, destabilizes the area in question. Another drawback of these systems is that the density of the protective cover, i.e., the amount of space between each unit, is not easily adjustable—to adjust the density of the cover, one must go through the time-consuming and burdensome task of placing one or more spacing members on or between each individual unit. 
     OBJECTS OF THE INVENTION 
     An object of this invention is to provide an apparatus which effectively controls erosion. 
     Another object of the invention is to provide an erosion control apparatus which allows a cover of vegetation to grow at the protected site. 
     A further object of the invention is to provide an erosion control apparatus which is easy to transport and install. 
     An additional object of the invention is to provide an erosion control device which is stable along all three dimensions. 
     Another object of the invention is to provide an erosion control device which has a density that is easily adjustable. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention features a protective network formed by connecting together modular components. Each modular component comprises two cross members of equal or unequal length pivotally connected to form an X-shaped apparatus. One or more link sites are located along the length of each cross member which allow the cross member to be pivotally connected to a cross member of a similar modular component. In this manner, each modular component can be pivotally connected to similar modular components located above, below, and to the left and/or right of the modular component to form a protective network. 
     Due to the shape of the inventive modules, the protective network contains a multitude of gaps. Accordingly, a top layer of soil and vegetation can be placed within and over the protective network to help anchor the soil and protect it from erosion. Additionally, to increase stability, a filter fabric layer can be placed over the installed network prior to adding the top layer of soil. Moreover, because each of the modules is connected to, as opposed to merely interlocked with, its neighboring modules, the resulting protective network is stable in all three dimensions. In a preferred embodiment, stability and erosion protection are further increased by the use of a plurality of legs projecting from the cross members and into the soil to help anchor both the soil and the protective network. Anchors, such as duckbills or cables, may also be used throughout the network to increase stability. 
     The density of the resulting network is also easily adjustable. Because the cross members of each module are pivotally connected, the angle between the members, and therefore, the amount of space between them and between the neighboring modules, can be increased or decreased merely by opening or closing the X-shaped module like a pair of scissors. This pivotal connection feature also makes transporting the inventive modules easier and less expensive than prior art modules because the inventive modules can be collapsed to facilitate shipping. 
     The design of the inventive modules also facilitates installation. Like prior art modules, the inventive modules can be placed in a row within a trench to form an anchoring base for the protective network. Because of the increased stability of the inventive modules, however, the trench used for the inventive modules need not be as deep as a trench used for prior art modules. Therefore, when installing the inventive modules, there is less work involved in digging the base trench, less excavated matter to carry away, and less sedimentation of the adjoining stream bank or other submerged area. The installation of the inventive modules is also easier and less expensive because they are lighter and more manageable than the heavier, more wieldly prior art modules. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a preferred embodiment of the invention. 
     FIG. 2 is a top elevational view of a preferred embodiment of a cross-member. 
     FIG. 3 is a side elevational view of the member of FIG.  2 . 
     FIG. 4 is a top elevational view of another preferred embodiment of a cross-member. 
     FIG. 5 is a side elevational view of the member of FIG.  4 . 
     FIG. 6 is a cross-sectional view of the apparatus of FIG. 1 along the line  53  of FIG.  1 . 
     FIG. 7 is a top elevational view of a protective network. 
     FIG. 8 is a perspective view of another preferred embodiment of the invention. 
     FIG. 9 is a top elevational view of a protective network. 
     FIG. 10 is a top elevational view of a protective network. 
     FIG. 11 is a side elevational view of another preferred embodiment of a cross-member. 
     FIG. 12 is a side elevational view of another preferred embodiment of a cross-member. 
     FIG. 13 is a top elevational view of a protective network. 
     FIG. 14 is a top elevational view of a protective network. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, module  10  comprises a primary member  15  and a secondary member  20 . Primary member  15  and secondary member  20  can be any suitable size or shape and can be made from any suitable material. In the preferred embodiment, module is an X-shaped apparatus and each member measures 24″×3″×1.75″ and is constructed from HDPE. 
     Each member has a pivot site  25  and one or more link sites  30  along its length. As shown in FIGS. 2 and 3, primary member  15  has a pivot site  25  and a plurality of link sites  30 . Similarly, as shown in FIGS. 4 and 5, secondary member  20  has pivot site  25  and link sites  30 . 
     Module  10  is constructed by attaching primary member  15  and secondary member  20  at their respective pivot sites  25 . In the preferred embodiment, primary member  15  is pivotally connected to secondary member  20  so that the members can rotate about the pivot sites  25 . This allows the module  10  to be opened or closed like a pair of scissors to achieve the desired angle  35  between primary member  15  and secondary member  20 . 
     Primary member  15  and secondary member  20  can be connected by any suitable fastening means, including, but not limited to, a nut and bolt, a pin or a rivet. In the preferred embodiment, primary member  15  and secondary member  20  are connected by snap locking a male coupling located at the pivot site of one of the members into a female coupling located at the pivot site of the other member. In the embodiment shown in FIGS.  1 - 6 , male coupling  40  is located on primary member  15  and female coupling  45  is located on secondary member  20 . Male coupling  40  features a rim  50  and female coupling  45  features channel  55 . When male coupling  40  is snapped into female coupling  45 , rim  50  fits snugly against channel  55  so that male coupling  40  is held securely but rotatably within female coupling  45 . 
     Just as the primary member  15  and secondary member  20  are connected to one another at the pivot sites  25  to form a module  10 , one module is connected to one or more other modules at the link sites  30  to form a protective network  60  (see FIG.  7 ). Modules can be connected at the link sites by any suitable fastening means, including, but not limited to, a nut and bolt, a pin or a rivet. In the preferred embodiment, the modules are connected at the link sites by the same type of coupling system used to link the members at the pivot sites, namely, by male and female snap-fit couplings. Because each of the modules is connected to, as opposed to merely interlocked with, its neighboring modules, the resulting protective network is stable in all three dimensions. 
     A member can have any number of link sites and those link sites can have male couplings, female couplings or a mixture thereof. For example, in the embodiment shown in FIGS. 4 and 5, secondary member  20  has two link sites  30  and each link site features a male coupling  40 . The primary member  15  shown in FIGS. 2 and 3, on the other hand, has three link sites  30 , one which features a female coupling  45  and two which feature male couplings  40 . The only requirement is that, if the link site on one module is being connected to the link site of another module, the couplings at those link sites must mate or engage with one another. 
     In any module, primary member  15  and secondary member  20  may be of equal or dissimilar lengths. In the module shown in FIG. 1, primary member  15  is longer than secondary member  20  and has an additional link site  30 . In contrast, in FIG. 8, module  10  has a primary member  15  and a secondary member  20  of equal lengths and have the same number of link sites. 
     The density of the protective network can be altered by connecting the inventive modules in different patterns. The patterns in which the modules can be connected will depend in part on the lengths of, and the number of link sites on, the members used to construct the modules. For example, FIG. 7 illustrates a protective network  60  which can be constructed using modules comprising a longer primary member  15  having three link sites  30  and a shorter secondary member  20  having two link sites  30 . 
     FIG. 9 illustrates a protective network  65  which can be constructed using different sets of modules. Modules  70  have a longer primary member  75  with three link sites  30  and a shorter secondary member  80  with two link sites  30 . In contrast, in modules  85 , primary members  90  and secondary members  95  are of equal length and have an equal number (three) of link sites. 
     Other possible network patterns are illustrated in FIGS. 13 and 14. The network of FIG. 13 comprises a series of modules  70  comprising members  15  and  20  of equal length, each member having two link sites  30 . The simple pattern of FIG. 13 is less dense than that of FIG. 7, for example, making it less expensive to install, but less effective at preventing erosion. The pattern of FIG. 13, therefore, may be more useful where the network is being used to combat relatively weak eroding forces. In contrast, the pattern of FIG. 14, because it is more dense and contains less repetitive shapes, is more expensive to install but is more effective at preventing erosion. It, therefore, may be the better pattern to pick where the network is being used to combat relatively high eroding forces. 
     Changing the pattern of the modules is not the only way to modify the density of the protective network. Changing the angle between the primary and secondary members will also change the density of the protective network. For example, the same pattern of modules is illustrated in FIGS. 9 and 10. However, protective network  65  in FIG. 9 is not as dense as protective network  100  in FIG. 10 because the angle  35  between the primary and secondary members is smaller in protective network  65  than it is in protective network  100 . 
     In a preferred embodiment, a plurality of legs extend from the primary and secondary members and into the protected soil to help anchor both the soil and the protective network. The legs can be shaped or canted to accommodate various environments. In the preferred embodiment illustrated in FIGS. 1,  11  and  12 , legs  105  and  110  are located opposite pivot sites  25  and link sites  30 . In an installed protective network featuring the module shown in FIG. 1, legs  110  located on secondary member  20  will project down into the soil on which the network is installed, while legs  105  will project up into the soil placed within and over the installed protective network. 
     While the present invention has been disclosed in terms of the preferred embodiments in order to facilitate better understanding of the invention, it should be appreciated that the invention can be embodied in various ways without departing from its basic principles. Therefore, the invention should be understood to include all possible embodiments and modifications to which do not depart from the invention as set out in the appended claims.

Summary:
An apparatus for use in erosion control comprising a primary member and a secondary member pivotally connectable to the primary member to form a unit. The unit can be connected to another like unit to form a protective network of such units.