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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to accessories for cemetery grave markers, and more particularly to a device that is releasably attachable to a substantially flat cemetery grave marker and provides one or more receptacles for supporting flower display vases above the upwardly facing surface of such grave markers.  
           [0003]    2. Description of Related Art  
           [0004]    Substantially flat cemetery grave markers are well known and are mandated for use in some cemeteries to facilitate mowing and other maintenance operations. Flat cemetery grave markers frequently contain a receptacle into which a vase can be inserted for the display of flowers. A device is needed, however, that can be easily installed and removed, and that will permit the display of more than one vase or floral arrangement and will also not interfere with mowing or other cemetery maintenance operations.  
           [0005]    Prior art references disclosing grave markers and/or related accessories include, for example, U.S. Pat. Nos. Des. 120,633; Des. 368,675; 1,843,602; 2,099,329; 2,623,616; 2,639,878; 3,145,847; 3,511,461; 4,640,045; 5,368,266; and 5,687,515.  
         SUMMARY OF THE INVENTION  
         [0006]    The invention disclosed herein is an extension device adapted to support vases above a substantially flat cemetery grave marker. The invention preferably comprises a frame member, the frame member further comprising an attachment member, and at least one vase support element that can be made of metal or unitarily molded from any suitable polymeric resin.  
           [0007]    According to one embodiment of the invention, an extension device is disclosed that is supportable above a substantially flat grave marker to provide one or more vase support elements, most preferably two laterally disposed vase receptacles, spaced above the marker. The device has a substantially horizontal frame member with an attachment member releasably connecting the frame member to a pedestal rising from the grave marker; and one or more vase receptacles attached to the frame member and spaced laterally apart from the attachment member.  
           [0008]    The attachment member preferably comprises a cylindrical ring or collar attachable to a pedestal that projects upwardly from the grave marker. In most circumstances, the pedestal is a vase of generally cylindrical configuration that is inserted into an upwardly facing well disposed in the top surface of the grave marker. According to one preferred embodiment of the invention, the attachment member also comprises structural members  28  disposed inside the ring or collar that rest on top of the pedestal. Securing means, such as screws threaded through the collar to function as set screws, releasably secure the attachment member to the upper portion of pedestal.  
           [0009]    The portions of the frame member connecting the attachment member to the two oppositely disposed vase receptacles is preferably sufficiently rigid to support the weight of vases and floral arrangements when they are inserted into the vase receptacles by the user. The vase receptacles themselves are preferably cylindrically shaped, and have at least one cross-member traversing the receptacle near the bottom edge of the sidewall, or other similarly effective means, for supporting a vase inserted into the receptacle above the surface of the underlying grave marker.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The apparatus of the invention is further described and explained in relation to the following figures of the drawings wherein:  
         [0011]    [0011]FIG. 1 is a front elevation view of a preferred embodiment of the extension device of the invention as installed above a substantially flat cemetery grave marker;  
         [0012]    [0012]FIG. 2 is a top plan view of the subject extension device; and  
         [0013]    [0013]FIG. 3 is a top perspective view of the extension device of FIGS. 1 and 2.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    Referring to FIG. 1, extension device  10  preferably comprises substantially horizontal frame member  12  and laterally spaced vase support elements, more particularly, vase receptacles  25 ,  26 , which are supported by pedestal  16  above the upwardly facing surface of a substantially flat grave marker  20  installed in surrounding earth  22 . Vase receptacles  25 ,  26  preferably comprise sidewalls  40 ,  36  and bottom support members  42 ,  38 , respectively. Referring to FIGS.  1 - 3 , frame  12  preferably further comprises a plurality of laterally extending, spaced apart rail members  24 , each of which is connected at one end to an attachment member comprising attachment ring or collar member  30 , cross-members disposed inside  28  and inner ring, or hub,  30 . Voids  32  are visible between rail members  24  and spokes  28 , and inside inner ring, or hub,  34 . Securing members, preferably thumb-screws  14 , are desirably threaded through collar member  30  for use in securing extension device  10  to the top portion of pedestal  16 .  
         [0015]    The diameter of attachment ring  30  is desirably such that attachment ring  30  will slip downwardly over the top of pedestal  16 , with support members resting on or near the top of pedestal  16 . As shown in FIGS. 2 and 3, the support members disposed inside attachment ring  30  are spokes  28  connected at one end to attachment ring  30  and at the other end to centrally disposed hub  34 . It will be appreciated, however, that the support members disposed inwardly of attachment ring  30  can be otherwise configured in any similarly effective manner such as, for example, a continuous or discontinuous annular flange projecting inwardly from attachment ring  30 , or as one or more transverse supports extending as chords across at least a portion of attachment ring  30  and connected thereto. Once attachment ring  30  is positioned over the top of pedestal  16 , and then lowered until the support member(s) inside attachment ring  30  are resting on the top of pedestal  16 , securing members such as threaded screws  14  can be tightened sufficiently to engage the upper sidewall of pedestal  16 . If desired, an annular lip or groove can be provided at or near the top of pedestal  16  to facilitate engagement by the forwardly extending ends of threaded thumb-screws  14 . It will be appreciated that the securing members such as screws  14  should desirably penetrate attachment ring or collar  30  along a locus of circumferentially spaced points that are disposed below the level of the support members inside attachment ring or collar  30  so that they can contact pedestal  16  while spokes  28  of frame member  12  are resting on the pedestal.  
         [0016]    It should also be understood that, while the preferred embodiment of the invention is shown and described herein in relation to an extension device  10  having two laterally spaced-apart vase receptacles  25 ,  26 , in some circumstances, extension device  10  can have only a single vase receptacle that is cantilevered over grave marker  20  by the frame member from attachment ring  30 . This might occur, for example, where a grave marker has a well for a vase or other pedestal that is situated at one end of the grave marker, rather than in the middle.  
         [0017]    As shown in FIG. 1, pedestal  16  can be a substantially cylindrical vase having a tapered base inserted into well  18  of grave marker  20 . It should be understood, however, that pedestals  16  having other configurations or attached to grave marker  20  by other means can likewise be used within the scope of the invention provided that frame member  12  is attachable to a pedestal  16  to support vase receptacles  25 ,  26  above grave marker  20 . If desired, the height of extension device  10  relative to grave marker  20  can be adjusted by using a pedestal  16  of differing length to support extension device  10 . Although the length of extension device  10  is most preferably substantially coextensive with the length of grave marker  20 , as shown in FIG. 1, it will also be appreciated more or less separation between vase receptacles  25 ,  26  can also be achieved where desired by lengthening or shortening frame  12  accordingly.  
         [0018]    Referring again to FIGS.  1 - 3 , it will be appreciated that bottom support members  42 ,  38  of vase receptacles  25 ,  26 , while shown in the preferred embodiment as webs spanning voids  32  between sidewalls  40 ,  36 , respectively, adjacent to the lower edges of the sidewalls, can also have a different structure within the scope of the invention. Thus, for example, vase receptacles  25 ,  26  can comprise a structure as disclosed inside attachment ring  30 , or an inwardly extending arcuate or annular flange adjacent the lower edge of sidewalls  40 ,  36 , provided that the support members inside the receptacles are sufficiently strong and durable to support a vase or other container and a floral arrangement. Similarly, the sidewalls  40 ,  36  are not required to be solid and continuous, provided that they are strong enough to anchor bottom support members  42 ,  38 , and strong enough to remain firmly attached to bar or rail members  24  of frame member  12  when, for example, receptacles  25 ,  26  are subjected to weather conditions as might be experienced during outside use.  
         [0019]    Frame member  12  and vase support receptacles  25 ,  26  as shown in FIGS.  1 - 3  can be made of metal or of a moldable polymeric resin that is durable enough to withstand the loads and weather conditions expected during use. Such well known and commercially available materials should be adequate for resisting exposure to moisture, wind and sun as might be expected over a prolonged period. Securing members  14  are desirably made of metal and coated to resist corrosion, particularly where frame member  12 , including attachment ring  30 , is made of a dissimilar metal. Whether made of metal or a polymeric material, attachment ring or collar  30  should be provided with aperture of sufficient diameter and structure so that securing members such as threaded thumbscrews can be threaded through the ring or collar and into engagement with pedestal  16 .  
         [0020]    Other alterations and modifications of the invention will likewise become apparent to those of ordinary skill in the art upon reading the present disclosure, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventor is legally entitled.

Summary:
An extension device supportable above a substantially flat grave marker to provide one or more vase receptacles spaced above the marker, the device having a substantially horizontal frame member with an attachment member releasably connecting the frame member to a pedestal rising from the grave marker; and one or more vase receptacles attached to the frame member and spaced laterally away from the attachment member.