You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     The present invention relates generally to swimming pool copings and particularly to a two-piece swimming pool coping in which the parts are pivotally or hingedly joined together and also snap-fitted together. 
     Swimming pool copings basically provide a marginal edge for a swimming pool. They usually provide a means by which a swimming pool liner may be easily attached to the edge of a swimming pool. They can also provide a safe, esthetically pleasing finish for the edge of a swimming pool. A wide variety of swimming pool copings have been proposed including one-piece, two-piece and multiple-piece structures. The copings have been made of metal, plastic, wood and/or combinations thereof. 
     A one-piece type coping which has achieved some degree of success is represented by U.S. Pat. No. 3,298,039. Such coping has a curved or bull-nosed edge, a socket or channel below the curved edge for receiving a pool liner, and a channel for receiving an anchoring bolt. In such construction the anchoring bolts must be fully installed before the coping can be slidably inserted on the bolt-heads. Should an anchor bolt subsequently become loose, the coping must be cmpletely removed to obtain access to the bolt. Another one-piece plastic type coping is illustrated by U.S. Pat. No. 3,335,429. Such coping requires a number of longitudinal ridges for strength and stability. A structure providing a one-piece cover which fits over a one-piece base is set forth in U.S. Pat. Nos. 3,512,326 and 3,579,665. 
     A multi-part coping is shown in U.S. Pat. No. 3,416,165. 
     One type of two-piece coping is seen in U.S. Pat. No. 3,310,814. Another type is set forth in U.S. Pat. No. 3,673,751. 
     Other examples of swimming pool copings are represented by U.S. Pat. Nos. 3,590,400; 3,628,198; 3,634,892; 3,777,318; 3,835,481; 3,839,748; 3,840,908; and 3,959,830. 
     The present invention provides a two-piece coping which provides the simplicity and smooth appearance of a one-piece coping and which can be quickly and easily assembled. 
     The present invention especially provides an installation which permits ready access to anchor bolts or other fastening members employed to secure the coping around the pool edge. 
     Another object of the invention is to provide an aluminum swimming pool coping which allows a top fastener to the pool side in a hidden position. 
     A further object of the present invention is to provide a two-piece coping of either metal or plastic in which one piece serves as a cover plate and the other piece holds the pool liner and fastener. 
     Still another object of the invention is to provide a finished or installed swimming pool coping which has a smooth and attractive appearance. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a two-piece swimming pool coping. One piece is an edge piece which includes a base plate for anchoring the coping to the pool edge or wall, a curved or bull-nosed part extending from the base plate, a channel below the curved part for receiving the edge of a pool liner, a hooked member for pivotally or hingedly engaging the other piece, and fastening means on the base plate for fastening the other piece to the base plate. The other piece is a cover piece which includes an opening therein for pivotal or hinged engagement with the hooked member of the edge piece and means extending therefrom for fastening the cover piece on the edge piece. When assembled together, the coping presents a relatively even surface for a person to stand upon. 
     The present invention also provides for a clip which substantially conforms to the outer shape of the assembled two-piece coping and which is mounted over the assembled coping to prevent separation of the two coping parts. A plurality of the clips are fastened on the coping members at appropriate places around the perimeter thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of the assembled coping of this invention attached to a fragment of the edge or wall of a swimming pool and a vertical side view of a clip of the invention illustrating the manner in which the clip is positioned on the coping; 
     FIG. 1A is a cross-sectional view of an alternate embodiment of the cover piece of this invention; 
     FIG. 2 is a perspective view of the cover piece of FIG. 1; 
     FIG. 3 is a perspective view of the edge piece of FIG. 1; and 
     FIG. 4 is a perspective view of the clip of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail, particularly FIGS. 1-3, the present invention is illustrated by a swimming pool coping formed in two parts or pieces. There is an edge piece 11 which is attached to the margin of the pool, and an edge piece or cover piece 12 which is attached to the edge piece. Each piece is preferably an aluminum extrusion or shape, but could also be formed of a suitable plastic. The edge piece is fastened to the pool side and is so constructed as to accept fasteners and the pool liner. The latter is preferably of vinyl or other suitable heavy duty plastic. The cover piece is pivotally engaged and snap-fastened to the edge piece. 
     The edge piece 11 has a bull-nose or curved part 13 extending from a base plate 14 and joined thereto by a short vertical member 15 which is perpendicular to the base plate. A portion 13a of the bull-nose member 13, short member 15 and a portion 14a of the base plate 14, form a channel or socket 16 for receiving the beaded edge of a swimming pool liner 17 to hold it in place on the swimming pool wall 18. The member 14a has a lip 14b extending therefrom to aid in holding the vinyl liner 17 in place. The base plate 14 has a short, lateral member 20 extending perpendicularly therefrom near the other end of the base plate. Also extending from the base plate 14 is a vertical and angular lateral member 21. The member 21 has a lip 21a formed thereon. The top portion 13b of the bull-nose part 14 extends slightly downwardly and has a curved member 13c on the end thereof. The member 13c has a curved channel 13d therein. 
     As seen in FIGS. 1 and 2, the cover piece 12 has a main top part 22 which has a slight downward slope from one end thereof to a curved end 23 which joins vertical member 24. Extending inwardly from the end of the vertical member 24 is short flange 25. Also extending downwardly and vertically perpendicularly from main top part 22, when in its installed position, is vertical member 26. A lip 26a is formed on the end of the member 26. One end of the member 22 extends to a rounded or beaded part 27 which has a curved part 28 extending therefrom. A vertical member 29 extends downwardly from the curved member 28 and a flange 30 extends at right angles from the member 29. One edge 30a of the member 30 is somewhat angular. A short flange 31 extends downwardly perpendicularly from the member 30. A curved channel 32 is formed by the beaded edge 27 and the curved member 28. The beaded edge 27 is adapted to fit into channel 13d. Curved member 13c is adapted to fit into channel 32. Such arrangement provides a pivotal or hinged connection between the edge piece 11 and the cover piece 12. When the two pieces are joined together, the member 31 rests against the member 15 and the lip 26a interlocks with the lip 21a. Flange 25 rests on base plate 14. 
     The base plate 14 is conveniently anchored to the wall 18 of the swimming pool by bolt 35 extending through the wall 18 and through an opening in the base 14 and with nut 36 tightened on the bolt 25. 
     A non-slip surface is provided by a plurality of longitudinally extending ridges or striations 37 on the top of the member 22 and similar ridges or striations 38 on top of the member 13b. 
     The piece 11 and the piece 12, when joined together and locked in place, form the swimming pool coping of the instant invention. When two copings, i.e., an assembled edge piece and cover piece, are joined together in an end-to-end relationship, a coping cover piece 40 is preferably snapped thereover. Such coping piece has a curved edge 41 which follows the general contour of the top of cover piece 12 and top piece 13b of edge piece 11. The member 40 also has a bull-nose shaped end 42 which is generally of the configuration of bull-nose part 13. Extending on the other end of the member 40 is leg 43 which extends downwardly and vertically of a configuration approximating that of the parts 23, 24 and 25 of the member 12. Extending from the leg 43 is lip 44. The member 40, when placed on the coping, effectively covers the space or joining area of two swimming pool copings. 
     Referring now to FIG. 1A, an alternate cover piece 50 is illustrated. The cover piece 50 is substantially the same as cover piece 12 except that the member 29&#39; extends vertically downwardly from curved part 28&#39; and ends in flange 51 which rests on the base plate 14. The additional construction of the member 50 is similar to that of the member 12. It can be appreciated that a variety of configurations and/or joining arrangements can be utilized without departing from the spirit of the invention. 
     The edge piece and the cover piece which form the swimming pool coping are preferably aluminum shapes. They may, however, be of plastic or other suitable material. The joining cover member 40 is also preferably aluminum, but may also be steel, plastic or any other suitable material. Such material is preferably somewhat flexible so that it may be readily snapped over the swimming pool coping. Although the cover or clip is preferred, it may of course be omitted. 
     While the invention has been disclosed herein by reference of the details of the preferred embodiment, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, and it is contemplated that various modifications of the construction and arrangement of the parts will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims.

Summary:
A two-piece coping for a swimming pool comprising an edge piece and a cover piece. The edge piece includes a base plate for fastening to the top of a pool wall, an opening for receiving a pool liner, an opening for pivotally engaging the cover piece, and means on the base plate for engaging fastening means on the cover piece. The cover piece includes means for pivotally engaging the edge piece and means for fastening the cover piece to the fastening means on the base plate of the edge piece.