referring now to the drawings in greater detail , fig1 - 6 illustrate a first embodiment 10 of the interior rearview mirror mounting adaptor for vehicles . adaptor 10 includes a body 12 having an open ended , recessed channel 14 on its windshield facing , back or rear surface 16 ( fig3 and 5 ) and a front projection 18 extending toward the interior of the vehicle for receiving the channel - like mounting member or &# 34 ; channel mount &# 34 ; 50 ( as it is known in the u . s . vehicle industry ) from a rearview mirror assembly as shown in fig2 and 12 . projection 18 thus forms a securing structure for removably attaching or mounting a rearview mirror assembly to the adaptor . likewise , recessed channel 14 forms a mount for removably securing the entire adaptor to a window or windshield mounted support . as shown in fig2 adaptor 10 is preferably adapted to be slidably fitted over a conventional windshield support member or windshield &# 34 ; button &# 34 ; such as that shown at 20 in fig2 , 7 and 8 or that shown at 34 in fig9 and 10 . windshield support member 20 includes an elongated support body 22 having a planar rear surface 24 ( which faces the front of the vehicle when installed ) adapted to be adhered by a suitable adhesive such as polyvinyl butyral ( pvb ) to the inside surface of a windshield as shown in fig2 . front surface 26 of body 22 is also generally planar and faces inwardly of the vehicle interior when mounted on the windshield . on either lateral side edge of the body 22 are tapered side edges or flanges 28 , 30 which taper inwardly toward the narrower rear surface 24 . also , side edges 28 , 30 are nonparallel with and extend toward one another at the top end of the body 22 as seen in fig6 . this provides the support member with its overall double wedge shape for receiving a channel mount such as that at 50 in fig1 and 12 . the top end of body 22 is rounded and may also be tapered inwardly toward rear surface 24 as at 32 . alternately , another conventional windshield support member 34 may be used as shown in fig8 and 9 . support 34 has a body 36 including planar rear and front surfaces 38 , 40 and rectilinear side edges or flanges 42 , 44 which extend perpendicularly outwardly from the sides of body 36 . flanges 42 , 44 are generally parallel with one another and provide an l - shaped shoulder area on either lateral side for retaining a channel mount such as that shown at 50 in fig1 and 12 . thus , support 34 has a different sectional shape than support 20 for matching a different sectional shape in a modified channel mount . the top end 46 of support member 34 is rounded and may be tapered inwardly toward rear surface 38 as in support member 20 . with reference to fig2 and 12 , a conventional channel - like mounting member or &# 34 ; channel mount &# 34 ; 50 is shown . such mounting members have been used for many years in the u . s . vehicle industry to support rearview mirror assemblies on windshield mounted support members as illustrated . channel mount 50 typically includes a body 52 cast from zinc or molded from a strong resinous plastic and has a recessed channel on its rear surface defined by longitudinal flanges 54 , 56 which extend out and over the rear surface 53 of body 52 and a closed , rounded top end 58 . projecting outwardly from body 52 and formed integrally therewith is a neck 60 and ball member 62 which are adapted to mate with a corresponding socket member to form a swivel joint for supporting a rearview mirror assembly in the conventionally known manner . depending on the precise shape of flanges 54 , 56 , channel mount 50 is adapted to slide over mounting support member 20 or 34 with support member 20 or 34 received through the bottom opening between flanges 54 and 56 . support member 20 or 34 slides into the channel until top end 32 or 46 abuts end 58 while flanges 54 , 56 engage side edges 28 , 30 or flanges 42 , 44 for retention purposes . as shown in fig2 mounting adaptor 10 is also slidably fitted over the top end of a conventional windshield mounted support member such as that at 20 or 34 in a manner similar to channel mount 50 . support member 20 or 34 has previously been secured or adhered to the inside surface of windshield w . after adaptor 10 is fitted , a channel member 50 is then slidably mounted over projection 18 such that ball member 62 projects substantially horizontally into the vehicle interior and properly positions the rearview mirror assembly for use by the driver of the vehicle . as is best seen in fig3 and 5 , the channel recess 14 at the rear of adaptor 10 is formed by flanges 64 , 66 which extend along the sides of body 12 on rear surface 16 and have inwardly extending surfaces 68 , 70 . surfaces 68 , 70 extend at an angle to one another to form a double taper or double wedge in the channel recess . a rounded top wall 72 ( fig3 ) closes the top end of recess 14 between flanges 64 , 66 . at the bottom end of adaptor 10 is an opening 73 between flanges 64 , 66 through which the support member 20 may be inserted and slid upwardly until top end 32 abuts top wall 72 as shown in fig2 . as will be seen in fig5 inwardly extending surfaces 68 , 70 are adapted to engage and mate with side edges 28 , 30 on windshield support member 20 to firmly support the adaptor on the windshield mounting button without play or vibration . since the thickness of support 20 or 34 is greater than the depth of channel 14 , adaptor 10 is spaced outwardly of windshield w . this allows the adaptor to be easily installed and prevents noise from contact between the adaptor and windshield . as shown in fig2 and 5 , projection 18 on the front surface 74 , of adaptor 10 is elongated in the direction of adaptor 10 and includes laterally extending retaining flanges 76 , 78 which extend along the lateral sides of projection 18 . flanges 76 , 78 extend parallel to surface 74 and form an l shape on each side of projection 18 to provide a shoulder for retaining channel mount 50 . the lower edges 77 , 79 of flanges 76 , 78 are rounded inwardly to avoid sharpness to reduce the chance of injury to occupants of the vehicle . the upper end 80 of projection 18 is likewise rounded and may be tapered inwardly as shown in fig2 and 6 for engagement with the top wall 58 in a channel mount such as that at 50 . projection 18 is also slightly thicker than the depth of the channel included in channel mount 50 . this spaces the channel mount slightly away from surface 74 as shown in fig2 to allow ease of insertion and to prevent contact between the mount and surface 74 . as shown in fig1 - 4 , an aperture 82 is provided through projection 18 and body 12 of adaptor 10 such that it opens into the recessed channel 14 behind the adaptor and opens toward the front or interior of the vehicle as well . aperture 82 is preferably threaded , extends at an upward angle toward the top of body 12 , and receives a set screw 84 which may be tightened against the front surface 26 or 40 of one of the windshield mounted support members 20 or 34 . the set screw draws surfaces 68 , 70 against surfaces 28 , 30 or flanges 42 , 44 to tightly retain the adaptor 10 on the support member 20 or 34 without vibration , play or release . when a channel mount such as that at 50 is slidably received over projection 18 , aperture 82 and set screw 84 are concealed from view . front surface 85 of projection 18 ma also include a conical recess 86 for receiving the end of a set screw from a channel mount 50 as shown in fig2 and explained more fully below . when received over projection 18 , through the opening between flanges 54 , 56 in the channel mount , flanges 76 , 78 engage flanges 54 , 56 while end 80 engages top wall 58 in the channel mount . although flanges 54 , 56 securely retain the channel mount on the projection while gravity holds end 80 against top wall 58 , additional protection against vibration or sliding movement of the channel mount on projection 18 is provided by a set screw 59 received in aperture 61 in body 52 of the channel mount . when tightened , set screw 59 is received in recess 86 to draw flanges 54 , 56 tightly against the inside surfaces of flanges 76 , 78 for more secure retention . alternately , as will be explained below , aperture 82 may be enlarged and left unthreaded such that an elongated fastener on a channel mount may be received entirely through the adaptor 10 for direct engagement with the front surface 26 or 40 of support member 20 or 34 . thus , such an elongated fastener in the channel mount would simultaneously secure both the channel mount 50 to adaptor 10 and adaptor 10 to support member 20 or 34 without the need for a second fastener ( see fig1 ). as will also be understood , the precise sectional shape of channel recess 14 on the rear surface of adaptor 10 may have the double tapered , wedge shape of support member 20 or the rectilinear l flange shape of support member 34 . likewise , projection 18 may have the same shape as channel recess 14 or a different shape as is shown in fig5 such that adaptor 10 will allow support of a rearview mirror assembly having a channel mount with a different sectional shape than that of the support member already secured to the windshield surface . preferably , adaptor 10 is formed from sintered metal or is die cast from zinc or another casting metal . alternately , the adaptor may be molded from high strength resinous plastic material such as glass filled acetal . in any event , it is preferred that the material from which adaptor 10 is made be sufficiently rigid and strong to properly support the rearview mirror assembly on the windshield mounted support member . referring now to fig1 - 18 , a second embodiment 90 of the mounting adaptor is illustrated . adaptor 90 includes an adaptor body 92 which is similar in its upper portions to adaptor 10 but extends downwardly to form a mounting receptacle for a vehicle accessory such as the headlight dimmer sensor 130 shown in fig1 , 15 and 16 . the rear surface 94 of adaptor 90 ( fig1 - 16 ) includes a recessed channel 96 similar in all respects to recessed channel 14 in adaptor 10 . channel recess 96 is adapted to receive a double tapered or wedge - shaped windshield mounted support member such as that shown at 20 in fig7 and 8 in the same manner as does recessed channel 14 as described above . channel 96 includes inwardly tapered flanges 98 , 100 which are nonparallel and extend toward one another at the top end of the adaptor which is closed by top wall 102 . a bottom opening 103 is included between the lower ends of flanges 98 , 100 . on the front surface 104 of adaptor body 92 is an elongated projection 106 similar to but of different sectional shape from projection 18 on adaptor 10 . projection 106 has a sectional shape which is substantially identical to that of channel recess 96 . hence , adaptor 90 may be fitted between a windshield mounted support member 20 and a channel mount 50 which would otherwise be received on support member 20 such that adaptor 90 spaces the channel mount outwardly from the support member 20 but otherwise secures it in the same manner . as explained below , adaptor 90 also provides support structure for a vehicle accessory adjacent the rearview mirror assembly such that the accessory is conveniently located for driver use or operation adjacent the mirror assembly . yet , adaptor 90 allows removable attachment of rearview mirror assemblies without disturbing the accessory likewise , the accessory does not interfere with use of the rearview mirror assembly . with reference to fig1 and 15 - 17 , the accessory support structure on adaptor 90 includes a pair of parallel , generally planar sidewalls 116 , 118 which are inteqral with and extend downwardly from the side edges 93 , 95 of adaptor body 92 beginning at an area approximately even with the midpoint of projection 106 . sidewalls 116 , 118 form the lateral sides of a rectangular receptacle 120 which also includes an angled rear wall 122 which extends downwardly from the lower end of adaptor body 92 as well as a forward wall 124 which faces the interior of the vehicle when the adaptor is mounted on the windshield support member 20 . intermediate sidewalls 116 , 118 is a top wall 126 which defines the bottom of a depressed well partially enclosing projection 106 . wall 126 also includes a wiring aperture 128 through which electrical wiring for operating the accessory supported in receptacle 120 extends as shown in fig1 and 15 . as will now be understood from fig1 , 15 and 16 , a vehicle accessory such as a headlight dimming sensor 130 , including a housing 132 having a light receiving opening 134 and mounting flanges 136 , 138 , is received in the opening to receptacle 120 by engagement with walls 116 , 18 , 122 and 124 . dimming sensor 130 includes an appropriate light sensing / electrical signaling device 140 connected to a slide switch 142 controlling the operation of the dimmer and an appropriate electrical circuit included on circuit board 144 which is connected to the vehicle electrical system via wiring 146 passing through aperture 128 in top wall 126 . when positioned on the windshield mounted support member 20 , which is slanted at the rearwardly inclined angle of the windshield , adaptor 90 supports receptacle 120 such that it opens vertically downwardly and holds the housing 132 of headlight dimming sensor 130 substantially horizontally such that opening 134 is aligned toward the front of the vehicle . headlights impinging on the vehicle from the opposite direction are received through opening 134 on sensor 140 when switch 142 is on . as shown in fig1 , a rearview mirror assembly supported by channel mount 50 may be supported on projection 106 simultaneously without affecting sensor 130 . when so mounted , the channel mount 50 extends partially into the well partially enclosing projection 106 and is secured directly to the front surface 26 of support member 20 by fastener 59 passing through aperture 114 . this simultaneously retains adaptor 90 in position on the support member 20 and eliminates the need for a second fastener as used in embodiment 10 . if desired a wire cover having a snap - on , clamp - type mount of the type disclosed in co - pending , commonly assigned united states patent application ser . no . 021 , 636 , filed mar . 4 , 1987 , the disclosure of which is hereby incorporated by reference , may be attached to channel mount 50 to shield and conceal wires 146 as they extend from adaptor 90 along the inside surface of windshield w to the headliner area of the vehicle . as with adaptor 10 , adaptor 90 may be formed from sintered metal , cast from zinc or other metal , or molded from a suitably rigid resinous plastic material such as glass filled acetal . of course , support 120 may be used or modified to support other vehicle accessories such as a compass sensor , radar detector , information display , garage door opener , keyless entry system , vehicle security identification , rain sensor or navigation system receiver . also , the support may be included above as well as below the adaptor body with shapes designed for and fitted to the particular accessory being supported . further , supports both above and below the adaptor body may be used . for example , a compass sensor could be supported below the adaptor body and mirror assembly with an information readout for the compass supported above the adaptor body and mirror assembly for viewing by the vehicle occupants and driver . referring now to fig1 - 27 , a third embodiment 150 of the mounting adaptor is illustrated . adaptor 150 is a hybrid form of the invention including an adaptor body 152 , a housing 180 integral with and positioned below the adaptor body for a microphone for a cellular phone , dictation system or the like and its controlling circuitry and wiring , and a wire cover 200 also integral with the adaptor body and extending from the adaptor body in an opposite direction from the microphone housing . as is seen in fig1 and 20 , adaptor body 152 includes a front surface 154 on which is located a double tapered , wedge - type projection 156 substantially similar to projection 106 on adaptor embodiment 90 . a fastener aperture 158 extends through projection 156 and communicates with a recessed channel 160 ( fig2 and 24 ) on rear surface 162 . projection 156 includes inwardly tapered side edges 164 , 166 adapted to mate with flanges 54 , 56 on a channel mount such as that shown at 50 in fig1 and 12 for retention purposes . a rounded top end 168 joins flanges 164 , 166 . projection 156 has a thickness slightly greater than the depth of the recessed channel of channel mount 50 to prevent contact between mount 50 and surface 154 . recessed channel 160 on the rear surface of body 152 is formed by outwardly extending lateral flanges 170 , 172 having inwardly flared retaining surfaces 174 , 176 . flanges 170 , 172 are nonparallel and extend toward one another toward the top of body 152 and provide recessed channel 160 with a double tapered , wedge shape adapted to receive a windshield mounted support member 20 through opening 173 between the flanges as shown in fig7 and 19 . the depth of recessed channel 160 is slightly less than the thickness of support member 20 to prevent contact between adaptor body 152 and the inside windshield surface . accordingly , when positioned on a windshield mounted support member 20 , projection 156 will face inwardly toward the interior of the vehicle for receipt of a channel mount 50 which , in turn , supports a rearview mirror assembly . microphone housing 180 is supported below the adaptor body 152 while wire cover 200 extends upwardly toward the vehicle headliner above the adaptor body . although microphone housing 180 and wire cover 200 are adjacent the rearview mirror assembly , neither interferes with the operation , removability , or adjustability of the mirror assembly or vice - versa . microphone housing 180 includes a slightly trapezoidal housing 182 when viewed from the front which is integral with , extends continuously from , and is generally parallel to adaptor body 152 . an integrally formed generally cylindrical microphone cylinder 184 extends at an angle to the general extent of housing 182 . housing 182 is formed by four walls with a generally hollow interior as seen in fig2 and 23 . that hollow interior may receive a microphone sensor such as that shown at 186 and an appropriate microphone circuit board 188 and wiring 190 . the forward facing wall of housing 182 merges outwardly into microphone cylinder 184 which includes opening 185 through which sound waves may pass to microphone sensor 186 . a rectangular aperture 192 at the top wall of housing 182 is included for insertion of an appropriate mold part to allow formation of the bottom wall of projection 156 . aperture 192 also provides access to the interior of the housing to allow insertion of wires leading from any lights or electrical accessories in the adjacent rearview mirror assembly so they may be concealed behind wire cover 200 as they extend toward the vehicle headliner with wires 190 . top wall 183 of the housing is substantially planar and is adapted to lie adjacent to or abut the bottom of a channel mount such as that shown at 50 when received over projection 156 . thus , the general exterior shape of housing 182 merges into the general shape of the channel mount 50 . likewise , the side surfaces of adaptor body 152 generally lie flush with the side edges of channel mount 50 when mounted on projection 156 . at the upper end of body 152 wire cover 200 extends rectilinearly upwardly away from adaptor body 152 . wire cover 200 is a channel member including a front wall 202 and rearwardly extending sidewalls 204 , 206 which define a rear opening to the channel . front wall 202 merges into the top wall of adaptor body 152 while sidewalls 204 , 206 merge into the sidewalls of adaptor body 152 . the internal space within channel member 200 communicates with the recessed channel 160 at the rear of adaptor body 152 which , in turn , communicates with the internal space within housing 182 and microphone cylinder 184 as is shown in fig2 - 23 . in order to allow access space for wiring 190 to microphone circuit 188 and sensor 186 from the headliner area of the vehicle , through the interior space in channel 200 , a bifurcated , recessed channel 208 is formed in the rear surface 162 of adaptor body 152 . channel 208 includes left and right branches which merge adjacent the top and bottom of aperture 158 into a single channel . at the top of body 152 channel 208 merges into the interior space of channel member 200 . adjacent the bottom end of aperture 158 channel 208 merges into the interior space of housing 182 and also communicates with aperture 192 . since channel 208 is deep enough to receive wiring 190 below the level of rear surface 162 , channel recess 160 may still receive windshield mounted support member 20 therein without causing obstruction or wear on wiring 190 . when inserted , wiring 190 continues unimpeded from the interior of housing 152 through channel 208 adjacent support member 20 when it is received in channel recess 160 and on into the interior of channel member 200 to the headliner area of the vehicle . since the distance between the support member 20 on the windshield &# 39 ; s inner surface and the vehicle headliner is different for each type of vehicle , mounting adaptor 150 may be provided with an extension for wire cover 200 as shown in fig2 - 27 . such extension is provided by a second rectilinear channel member 210 which slidably telescopes over channel 200 and includes a front wall 212 which is slightly wider than the entire width of channel 200 and a pair of parallel , rearwardly extending sidewalls 214 , 216 which extend along the exterior surface of sidewalls 204 , 206 as shown in fig2 - 27 . in order to position channel extension 210 with respect to channel member 200 , a series of semi - spherical depressions 218 are formed in the outer surfaces of sidewalls 204 , 206 of channel 200 near the upper end thereof . a pair of inwardly extending semi - spherical projections 219 are formed on the inner surface of sidewalls 214 , 216 of channel extension 210 adjacent its lower end for receipt in an opposing pair of semi - spherical recesses 218 . accordingly , when the distance between the support member 20 and the headliner is known , the channel extension 210 may be positioned to cover the extra distance between the upper end of channel 200 and the headliner and snapped into place with semi - spherical projections 220 received in one pair of the semi - spherical recesses 218 to hold the extension in place . sidewalls 214 , 216 may be flexed outwardly sufficiently to allow insertion of the projections 219 into recesses 218 . also , upper end 220 of channel extension 210 may include a flange as disclosed in co - pending application ser . no . 21 , 636 referred to above for receipt under the vehicle headliner to help retain it in place . as with mounting adaptors 10 and 90 , adaptor 150 may be formed from sintered metal , or , more preferably , molded from a sufficiently rigid resinous plastic material in one piece . channel extension 210 may be separately molded from resinous plastic for the telescoping fit with channel 200 . when mounted on support member 20 via opening 173 to channel recess 160 , a microphone sensor 186 for a cellular phone , recording / dictation system or the like may be received in microphone cylinder 184 and is connected via wiring 190 to the vehicle electrical system . when a rearview mirror assembly including a channel mount such as that shown at 50 is received over projection 156 and secured through aperture 158 with fastener 59 on the channel mount to support member 20 , the mirror assembly is positioned in front of and immediately adjacent and above the microphone housing 180 . wiring 190 and any wiring leading from the mirror assembly is concealed from view in the passenger compartment by wire cover 200 and channel extension 210 as it extends to the headliner of the vehicle . both the mirror assembly and the microphone are thus conveniently positioned for access adjacent the driver while the microphone is in a position above the dashboard of the vehicle where voices from others in the passenger compartment of the vehicle can be properly received . of course , as with adaptors 10 and 90 , projection 156 may have a sectional shape different from that of recessed channel 160 so that the adaptor will effectively convert from one type channel mount or rearview mirror assembly to another . while several forms of the invention have been shown and described , other forms will now be apparent to those skilled in the art . therefore , it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes , and are not intended to limit the scope of the invention which is defined by the claims which follow .