the snow shoe which is to be equipped with the device according to the present invention can , of course , be of any type . an exemplary snow shoe is represented in fig1 and 2 . as is illustrated in fig1 and 2 , the snow shoe designated under general reference 100 is presented , for example , symmetric about a plane of symmetry p fixed below the shoe . a principal frame 200 which delimits an interior zone comprises a set of internal walls supporting the retention device , more commonly called binding 1 , destined to retain the boot or shoe 2 of the user . said principal frame has , for example , a generally elongated shape , with a tail 3 of reduced width extending to the rear , as well as a raised front with slightly pointed shape in order to constitute a front spatula 4 . the snow shoe can , of course , also have any other shape , without going outside the scope of the invention . the boot or shoe 2 of the user is retained at the snow shoe proper by the device according to the invention , bearing the general reference 1 and which is principally constituted by a front retention means 5 comprising a set of holding walls 9a , 9b , 10a , 10b , 11 , 12 , 13a , 13b forming an enclosure or cavity 8 , open toward the rear , in which is engaged and retained a front extremity 2a of the shoe 2 . furthermore , a rear extremity or heel 2b of the shoe 2 is held by a rear retention means 6 , the installation of which causes the cavity 8 to close on and / or around the front extremity 2a of the shoe 2 . the boot or shoe is urged toward the front av and into the front retention means 5 by a traction strap or member 21 , passing behind the heel of said shoe , which constitutes the rear retention means 6 for the latter . the traction device 21 forms a retention loop for the shoe and constitutes an extension for a tensioning agent 18 for contracting the cavity 8 . this latter includes one or several cables 18a , 18b whose traction provokes the closing or contracting of the cavity 8 on the front extremity 2a of the shoe 2 . a tensioning force is placed on the tensioning agent 18 by closing the rear retention means 6 . to that end , the traction member 21 is , for example , constituted by a strap or belt connected with and extending from the tensioning agent 18 . the traction member includes a means for adjustment and locking 22 such as one or several adjustment and locking buckles 22a , 22b . the contracting of the cavity 8 over the front extremity 2a of the shoe 2 thus takes place automatically with installation of the rear retention means 6 . according to a first specific embodiment of said device , the front retention means 5 are constituted by an enclosure or cavity 8 , open toward the rear ar composed of two lateral holding walls 9a , 9b , beneficially linked between each other by upper connection means 10 , by a lower wall called a sole plate 11 , and a front stop wall 12 as illustrated in fig3 . according to this first embodiment , the front stop wall 12 is an extension of the sole plate 11 of the retention device 1 . said sole plate 11 is mounted in a pivoting manner around an approximately transverse axis xx &# 39 ; of the snow shoe 100 or is fixed on an intermediary plate , pivoting according to xx &# 39 ; in a manner known per se . the lateral holding walls 9a , 9b arranged on all sides of the shoe 2 of the user , are each articulated relative to the front stop wall 12 . it should be noted that said articulations beneficially occur according to the approximately vertical axes y1y &# 39 ; 1 or y2y &# 39 ; 2 . according to this first specific embodiment , the lateral holding walls 9a , 9b are made of flexible or deformable , even slightly elastic material , and constitute extensions of said front stop wall 12 . thus , the articulation is obtained by folding or deformation . however , the articulation of the walls could be constituted by a hinge or by any other equivalent means , without going outside the protective domain claimed under the invention . these articulations of the lateral holding walls 9a , 9b in relationship to said front stop wall 12 according to axes y1y &# 39 ; 1 and y2y &# 39 ; 2 permit them to be transversely pulled , one toward the other , at the closing of the cavity 8 around the front extremity 2a of the shoe 2 . each lateral holding wall 9a , 9b comprises , in addition , two upper wall extensions 13a , 13b of rounded shape , directed toward the interior of the enclosure 8 and destined to spread out transversely above the front extremity 2a of the shoe 2 . furthermore , these upper wall extensions 13a , 13b are symmetrically arranged on all sides of the shoe 2 and are each fitted with a transverse , elongated slot 14 . an upper connection means 10 of this first embodiment are constituted by two upper support walls or strips 10a , 10b , that is to say , one front upper support wall or strip 10a and one rear upper support wall or strip 10b , arranged transversely between two upper extensions of the wall 13a , 13b symmetrically to lateral holding walls 9a , 9b . these upper support strips 10a , 10b have at the extremities on their lower surfaces 15 gripping teeth 16 or gripping detents or gripping pins , which slide in the transverse slots 14 of the upper wall extensions 13a , 13b of the lateral holding walls 9a , 9b . the upper support strips 10a , 10b are pulled downwards ba while sliding toward the lateral holding walls 9a , 9b when the rear retention means 6 are put in place . furthermore , these support strips 10a , 10b are beneficially rounded or convexly curved in shape in a manner so as to be able to superimpose themselves upon the upper extension of the wall 13a , 13b and thus facilitate the sliding of the gripping teeth 16 into the transverse holes . the tensioning agent 18 controls the sliding of the pins 16 into the transverse slots 14 of the upper extensions 13a , 13b . more specifically to the first embodiment , two cables 18a , 18b are symmetrically arranged on both sides of the retention device 1 . each cable 18a , 18b is fixed on the front of the sole plate 11 or on the front stop wall 12 at one of its extremities . each cable then passes on the outside of the lateral holding wall 9a , 9b and its upper wall extension 13a . it then twists around a first pin 16 while passing between the upper wall extension 13a and the lower surface 15 of the upper support strips 10a , 10b around said pin 16 . it then passes through a return means 19a of the sole plate 11 , prior to twisting in identical fashion to the second pin 16 . finally , it passes through another return means 19b of the sole plate 11 and attaches at its other end to the rear retention means 6 . these rear retention means 6 are constituted by a traction or tensioning agent 21 , formed by a retention belt 21 , each end of which is attached to an extremity of one of the cables 18a , 18b of tensioning agent 18 . in addition , these rear retention means 6 includes means of adjustment and locking 22 such as , for example , an adjustment and locking buckle 22 which permits varying the length of the belt or strap forming the loop 21 . thus , when the rear retention means 6 are put in place , the gripping action of the retention strap 21 , thanks to the adjustment and locking means 22 , pulls on the cables 18a , 18b , causing them to pull the pins 16 in downward direction ba sliding along the transverse slots 14 of the upper extensions of wall 13a , 13b . this downward sliding of the pins causes , thanks in part to the rounded shape of the upper support wall 13a , 13b , the transverse attraction of the lateral holding walls 9a , 9b toward one another . in this manner , the cavity 8 is contracted or closed around the front extremity 2a of the shoe 2 . in a second embodiment of the invention , illustrated in fig4 , 6 , and 7 , the retention device 1 includes front retention means 5 generally as previously described . a cavity 8 is formed by a sole plate 11 , a front stop wall 12 , two lateral holding walls 9a , 9b having two upper wall extensions 13a , 13b and two upper support walls or members 10a , 10b mounted in sliding fashion on said extensions . according to this second embodiment , the lateral holding walls 9a , 9b , each having a supplementary wall extension called rear connection extension 23a , 23b which extends longitudinally to the rear ar and which is fitted with a longitudinal hole or slot 24 into which a traction tooth , detent , or pin 25 slides under action of the traction agent 21 of the rear retention means 6 , as demonstrated in fig4 . in addition , the two pins 25 are each fixed to one end of one of the cables 18a , 18b of the tensioning agent 18 as well as to one of the extremities of the retention belt 21 forming the rear retention means 6 . according to the second embodiment , the cables 18a , 18b follow a path almost identical to that of the first embodiment . a final return means or guide 20 is situated on the lateral holding walls 9a , 9b and is arranged approximately in the extension of the longitudinal slot 24 of the rear connection extension 23a 23b perpendicularly to the upper wall extension 13b situated further in the rear , as illustrated in fig4 and 6 . the return means 19a , 19b , 20 of the sole plate 11 can be constituted , for example , either by semi - circular or semi - spherical , molded passages on the lower surface 26 of the sole plate 11 , or by passage holes arranged on an edge jutting out from below the sole plate 11 as is shown in fig6 . according to the second embodiment , the rear retention means 6 have as adjustment and locking means 22 two lateral adjustment and closing buckles 22a , 22b solidly joined each to a traction detent 25 as shown in fig4 . the belt forming the retention loop 21 is firmly attached at each of its extremities to one of the adjustment and closing buckles 22a , 22b and passes , moreover , through a rear passage 28 located at the rear extremity of the connection extensions 23a , 23b prior to passing around the heel of the boot or shoe 2 of the user . furthermore , the sole plate 11 can beneficially be equipped on its lower surface 26 with a front spike or cleat 29 as shown in fig5 or 6 . thus , according to the second embodiment , at the time when the rear retention means 6 are put in place , the gripping of the retention belt 21 provokes sliding to the rear ar of the traction detents 25 along the longitudinal slots 24 toward the rear of the extensions 23a , 23b communicating the pulling or tensioning forces toward the front av of the shoe 2 . said sliding allows traction on the cables 18a , 18b , forming the tensioning agent 18 to cause a displacement in the downward direction ba of the pins 16 of the upper support strips 10a , 10b along the transverse slots 14 of the upper wall extensions 13a , 13b . this displacement causes , due to the vertical articulation of the lateral holding walls 9a , 9b , a transverse drawing together of these , as well as downward displacement ba of the upper support straps 10a , 10b in a manner so as to contract the cavity 8 around the front extremity 2a of the shoe 2 . according to a variation , not shown , the tensioning agent 18 includes a single cable , whose ends are fixed to the two ends of the retention loop 21 of the rear retention means 6 by way of the detents 25 and the adjustment and closing buckles 22a , 22b . the path of the single cable is identical , with the exception that at the front , there is no cable fixation . instead , the single cable extends through a return or passage means , beneficially situated on the front stop wall or below the front extremity of the sole plate . according to another variation , the pins 16 are no longer arranged under the upper walls 10 or straps 10a , 10b in a manner so as to slide into the transverse slots 14 of the upper extensions of the wall 13a , 13b . rather , the pins are fixedly mounted on the upper surface of said extensions 13a , 13b in such a manner so as to slide into a slot or a guide in the upper support wall or member 10a , 10b . thus , the upper extensions of the wall 13a , 13b no longer have transverse slots . they have , beneficially , a smooth lower surface . in this embodiment , the cables 18a , 18b no longer attach directly to the pins 16 . instead , they are slidingly connected to the extremities of the upper support walls 10 or straps 10a , 10b , in a manner so as to be able to pull said upper support straps in the downward direction ba when the rear retention means 6 are pulled into place . thus , according to these embodiments and their variations , the lateral holding walls 9a , 9b are articulated , by pivoting on the front stop wall 12 around approximately vertical axes y1y &# 39 ; 1 and y2y &# 39 ; 2 in a manner as to pivot the one toward the other in an orthogonal horizontal plane to said axes when the rear retention means 6 are put in place . according to a third preferred embodiment illustrated in fig8 only one of the lateral holding walls is fitted with an upper wall extension 13a , 13b . one upper support wall or strap 10 is mounted in sliding fashion on said extensions . sliding takes place in an identical manner as the preceding embodiments . moreover , the front stop wall 12 is constituted by a connecting extension of the lateral holding walls . the retention device 1 has , as in the preceding embodiments , a tensioning agent 18 including cables , whose ends are solidly joined with the rear retention loop 21 on the one side , and the upper support wall 10 on the other side , in such a manner so as to permit the contracting of the cavity over the front extremity 2a of the shoe 2 when said rear retention buckle is put into place . according to this third preferred embodiment , the lateral holding walls 9a , 9b are articulated by pivoting on the sole plate 11 around two axes z1z &# 39 ; 1 and z2z &# 39 ; 2 , beneficially located in a horizontal plane . the lateral holding walls 9a , 9b can be constituted by an extension of the sole plate 11 or be fixed to the same by a fixation sling 30 . said sling is formed by an extension of the lateral holding walls and defines a connection means between the sole and the lateral walls . thus , articulation takes place , for example , by folding or deformation in length of a portion of the line or axis of said means of connection . it should be noted that in the preferred mode , as illustrated , the fixation slings 30 are extension in downward direction of the lateral walls . according to this third embodiment , the connection means are positioned approximately toward the front av of the sole . it goes without saying that said means of connection could also be positioned toward the rear , without consequently going beyond the field of protection of the invention . it should , in addition , be noted that the pivotal axes z1z &# 39 ; 1 and z2z &# 39 ; 2 come together at a point situated in front of the retention device 1 . however , depending upon the longitudinal position of the connection means said axes could , for example , extend parallel in the plane of the general symmetry p . it should be noted that , beneficially , the fixation slings are connections realized of flexible material . according to this embodiment , when the rear retention means 6 are put in place , the lateral holding walls 9a , 9b are pulled , through pivotal movement toward the sole plate 11 , around the approximately longitudinal axes z1z &# 39 ; 1 and z2z &# 39 ; 2 situated in the horizontal plane of the sole plate . as a result , the lateral holding walls are each pulled through pivotal movement into a vertical orthogonal plane to said axes . moreover , the front retention means 5 which include a positioning means of the rear retention loop 21 in such manner that they permit said loop to be held in an approximately horizontal place , situated slightly above the plane of the sole plate when the retention device 1 is in an inactive position , that is to say , prior to said loop being put into place , when it does not hold shoes . said positioning means thus permits placement of the retention loop 21 around the heels of the shoe , with assistance from the adjustment buckles 22a , 22b in maintaining the buckle in approximately similar position to its position of gripping , once put into place against the heel of the shoe . according to this embodiment , said positioning means are formed by means of rigid passages 28a , 28b beneficially situated at the extremity of the rear connection extensions 23a , 23b of the lateral holding walls 9a , 9b . said passages permit the holding of the semi - rigid belt , forming the retention loop 21 . according to a fourth embodiment illustrated in fig9 the retention device 1 has a front means 5 substantially as described in the third embodiment . an upper support wall or strap 10 is mounted in sliding fashion on the extensions of the upper walls 13a , 13b of the lateral holding walls , thanks to the detents . according to this embodiment , the tensioning agent 18 is constituted by two cables 18a , 18b whose paths , somewhat identical for each of them , differ from the path of the preceding embodiments . one end of the cable is fixed on the upper support wall or strap 10 closely to its respective lateral end 100 . the cable then passes through a lateral return point or guide 101 constituted , for example , by means of a passage hole situated in a lateral extension of the sole plate 11 , extending in an upward direction over the length of the lateral holding walls . the cable then passes through a return means 102 arranged on the lateral holding walls in a manner so as to return the cable toward the adjustment buckle 22a , 22b of the retention loop 21 and is fixated thereto . according to a fifth embodiment not illustrated , the front retention means are constituted by the two lateral holding walls and the sole plate . said lateral holding walls are articulated by folding the length of the line forming the intersection of same with the sole plate . one of the two lateral holding walls includes an upper wall extension intended to pass above the front extremity of the shoe in order to be mounted in sliding fashion on the other lateral wall . a tensioning agent , solidly attached to the rear retention means permits the control of this sliding and thus the closing of the cavity around the shoe . likewise , another variation includes realizing the cavity by utilizing an envelope or sheet of flexible material , with its edges lapping in a sliding relationship , for example the one relative to the other below the sole plate . by mutually covering each other , said sliding is directed by the tensioning agent which is solidly connected with the rear retention means . the invention has been described with reference to the preferred embodiment . obviously , modifications and alterations will occur to others upon reading and understanding the preceding detailed description . it is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof .
a binding for a snow shoe includes a front binding portion . the front binding portion includes a base plate from which a pair of side walls extend upward . the side walls have upward extensions which have transverse slots defined therein . upper wall portions or straps have detents which are slidably received in the slots . a heel engaging loop is connected with cables which engage the top wall portions or the detents . as the loop is pulled over the heel of the boots , the cables pull the detents downward through the slots , drawing the side walls together , contracting a cavity which they define tightly around the toe of the boot .