a first preferred embodiment of the toy ( 100 ) of the present invention is shown in fig1 a . the toy ( 100 ) has a string ( 105 ), or some other type of tethering means , such as a rope , thread or twine , on which are constrained two end bobs ( 120 . 1 ) and ( 120 . 3 ) and a middle bob ( 120 . 2 ). there are many modes of play with the toy ( 100 ) in this three - bob state . holding one end bob ( 120 . 1 ), the basic orbits are a vertical orbit , a horizontal orbit and a figure - eight / butterfly orbit of the middle bob ( 120 . 2 ) and the other end bob ( 120 . 3 ). other basic orbits , as well as gateway moves , advanced orbits , juggling tricks , string tricks , rebound tricks , and body tricks can be found in the tricks section of www . ap - club . net and in hundreds of player - posted online videos . according to the preferred embodiment of the present invention , each of the bobs ( 120 . 1 ), ( 120 . 2 ) and ( 120 . 3 ) has the same construction . ( generically or collectively the bobs ( 120 . 1 ), ( 120 . 2 ) and ( 120 . 3 ) will be referred to with reference numeral 120 .) a cross - sectional view of a bob ( 120 ) in a non - separated state is shown in fig2 a . the bob ( 120 ) has a central weight ( 130 ) with a throughbore ( 132 ), an upper spindle half ( 140 . 1 ), a lower spindle half ( 140 . 2 ), and an outer mantle ( 150 ). ( the spindles halves ( 140 . 1 ) and ( 140 . 2 ) will be referred to generically or collectively with reference numeral 140 . the components of the upper and lower spindles halves ( 140 . 1 ) and ( 140 . 2 ) will with reference numerals in the 14 x . 1 and 14 x . 2 series and will be referred to generically or collectively with reference numeral 14 x .) as shown in the cross - sectional views of fig2 a , 2 b and 2 b , the side view of fig4 a , and the perspective view of fig4 b , each spindle half ( 140 ) has a flared bore ( 142 ) and an outer frame ( 144 ). each spindle half ( 140 ) is cylindrically symmetric about a central axis ( 199 ) through the bore ( 142 ) except for three wings ( 143 ) which have three - fold symmetry about the central axis ( 199 ). at the terminal end ( 145 ) of each wing ( 143 ) is an inwards jutting lip ( 148 ). the diameter of the bore ( 152 ) of the mantle ( 150 ) is slightly greater than the diameter of the frame ( 144 ) and less than the outer diameter of the flare ( 146 ) of the bore ( 142 ). the weight ( 130 ) may be removably secured by the wings ( 143 ) and lips ( 148 ) within both spindles halves ( 140 . 1 ) and ( 140 . 2 ) as shown in fig2 a where the bob ( 120 ) is in its non - separated state and the mantle ( 150 ) is secured on the spindle halves ( 140 ) by the outer edges of the flares ( 146 ) of the bores ( 142 ). or the weight ( 130 ) may be secured in one or the other of the spindles halves ( 140 ) as shown in fig2 b where the bob ( 120 ′) ( an apostrophe after the reference numeral 120 indicates the separated state ) is in the separated state and the weight ( 130 ) is held by the bottom spindle half ( 140 . 2 ). the wings ( 143 ) have an azimuthal width ( i . e ., transverse to the throughbore axis ( 199 )) equal to the separation between the wings ( 143 ). therefore , two spindle halves ( 143 ) can be mated as shown in fig4 c . because the weight ( 130 ) can be secured in either spindle half ( 140 ) and two spindle halves ( 140 ) can be mated as shown in fig2 a and 4b , two spindle halves ( 140 ) can be secured together when both secure a centrally - located weight ( 130 ). the weight ( 130 ) in each bob ( 120 ) lowers the moment of inertia of each bob ( 120 ), as described in u . s . pat . no . re34 , 208 , providing smoother orbits , particularly vertical orbits . with the weight ( 130 ) ( which is not visible in fig4 c ) securing the spindle halves ( 140 . 1 ) and ( 140 . 2 ) in the mated configuration shown in fig4 c , the throughbores ( 142 . 1 ) and ( 142 . 2 ) of the spindle halves ( 140 . 1 ) and ( 140 . 2 ) provide a continuation of the throughbore ( 132 ) of the weight ( 130 ) to provide a throughbore for the string ( 105 ) through the bob ( 120 ). according to the present invention , the spindle halves ( 140 ) are considerably lighter than the weight ( 130 ) and the mantle ( 150 ). therefore , when a bob ( 120 ′) is in its separated state with one spindle half ( 140 . 2 ) holding the weight ( 130 ) while the separated components of the bob ( 120 ′) are orbiting , the other spindle half ( 140 . 1 ) will tend to remain in the bore ( 152 ) of the mantle ( 150 ). according to a preferred embodiment of the present invention , the mantle ( 150 ) has roughly the same mass as the weight ( 130 ), i . e ., m weight ≈ m mantle . therefore , the lower spindle half ( 140 . 2 ) with the weight ( 130 ) will orbit about the mantle ( 150 ) with the upper spindle half ( 140 . 1 ) in a balanced orbit . one such balanced orbit is depicted in fig5 a - 5c where the two end bobs ( 120 . 1 ) and ( 120 . 3 ) are held while the mantle ( 150 ) and first spindle half ( 140 . 1 ) orbits the weight ( 130 ) and second spindle half ( 140 . 2 ). when m weight ≈ m mantle ( and therefore m weight + m spindle half ≈ m mantle + m spindle half ), the orbit shown in fig5 a - 5c is a balanced orbit because the orbit would be the same if the mantle ( 150 ) and first spindle half ( 140 . 1 ) was replaced with the weight ( 130 ) and second spindle half ( 140 . 2 ) and vice versa , i . e ., if the position of the mantle ( 150 ) and first spindle half ( 140 . 1 ) was switched with the weight ( 130 ) and second spindle half ( 140 . 2 ). the orbit of fig5 a - 5c can also be seen to be balanced because of the symmetry of the paths of the partial bobs ( 120 ′) about the vertical plane between the two hands ( 160 ) and through the body of the player ( not shown ). furthermore , because a bob ( 120 ′) in its separated state still has a total mass equal to that of a bob ( 120 ) in its non - separated state , the center of mass of the two separated portions will orbit about a non - separated bob ( 120 ) in a balanced orbit . for instance , in the orbit depicted in fig6 a and 6b one end bob ( 120 . 1 ) is held while the other end bob ( 120 . 3 ) orbits the center of mass ( cm ) of a separated middle bob ( 120 . 2 ′) in a balanced orbit while the mantle ( 150 ) and first spindle half ( 140 . 1 ) of the separated middle bob ( 120 . 2 ′) orbits the weight ( 130 ) and second spindle half ( 140 . 2 ) of the separated middle bob ( 120 . 2 ′) in a balanced orbit . according to the present invention the mass m mantle of the mantle ( 150 ) is within 50 %, more preferably 35 %, still more preferably 20 %, and still more preferably 10 % of the mass m weight of the weight ( 130 ). furthermore , according to the present invention the mass m mantle of the mantle ( 150 ) plus the mass m spindle half of a spindle half ( 140 ) is within 50 %, more preferably 35 %, still more preferably 20 %, and still more preferably 10 % of the mass m weight of the weight ( 130 ) plus the mass m spindle half of a spindle half ( 140 ). according to the present invention , in the separated state the slideability of the components of a bob ( 120 ′) along the string ( 105 ) are substantially different than that of a bob ( 120 ) in the non - separated state . in particular , in the non - separated state the smoothly - contoured bore ( 142 ) of the ajoined spindles ( 140 . 1 ) and ( 140 . 2 ) slides smoothly and with a low sliding friction along the string ( 105 ) since the string ( 105 ) is not forced to bend at a sharp angle when it enters and exits the flare ( 146 ) of the bore ( 142 ) at an angle relative to the bore axis ( 199 ). in contrast , in the separated state , as shown in fig2 b and in play in fig5 a - 5c and 6 a - 6 b , the relatively sharp edge ( 151 ) at the end of the bore ( 152 ) of the mantle ( 150 ) forces the string ( 105 ) to bend at a sharp angle as it enters and exits the flare ( 146 ) of the bore ( 142 ) at an angle relative to the bore axis ( 199 ) and there is a high sliding friction . and the relatively sharp edge ( 131 ) at the end of the bore ( 132 ) of the weight ( 130 ) also forces the string ( 105 ) to bend at a sharp angle as it enters and exits the flare ( 146 ) of the bore ( 142 ) at an angle relative to the bore axis ( 199 ) and there is again an increased sliding friction relative to that of the non - separated bob ( 120 ). this allows moves requiring a higher sliding friction to be performed , such as the move shown in fig5 a - 5c . according to the preferred embodiment of the present invention , the radius of curvature in the cross - sectional plane shown in fig2 a and 2b ( which will be referred to in the present specification as the radius of curvature along the bore axis ( 199 )) of the flare ( 146 ) of the bore ( 142 ) of a half spindle ( 140 ) is at least 4 times , more preferably 8 times , still more preferably 12 times , still more preferably 16 times , still more preferably 25 times , and still more preferably 50 times that of the radius of curvature along the bore axis ( 199 ) of the end ( 151 ) of the bore ( 152 ) of the mantle ( 150 ). furthermore , according to the preferred embodiment of the present invention , the radius of curvature in the cross - sectional plane shown in fig2 a and 2b of the flaring region ( 146 ) of the bore ( 142 ) of a half spindle ( 140 ) is at least 4 times , more preferably 8 times , still more preferably 12 times , still more preferably 16 times , still more preferably 25 times , and still more preferably 50 times that of the radius of curvature along the bore axis ( 199 ) of the end ( 131 ) of the bore ( 132 ) of the weight ( 130 ). it should also be noted that the separability of the bobs ( 120 ) provides the ability to produce optical or magical illusions where one bob ( 120 ) appears to become two bobs . as is apparent from fig2 b , the upper part of the separated - state bob ( 120 ′) ( i . e ., the portion with the spindle ( 140 . 1 ) and mantle ( 150 )) looks the same as a complete bob ( 120 ) from above along the bore axis ( 199 ) as well as from a range of angles off the bore axis ( 199 ). because the width of the spindle ( 140 ) at the flaring end ( 146 ) of the bore ( 142 ) approaches that of mantle ( 150 ), the axially - central portion of the lower part of the separated - state bob ( 120 ′) ( i . e ., the portion with the spindle ( 140 . 1 ) and weight ( 130 )) can look almost the same as a complete bob ( 120 ) from below along the axis of cylindrical symmetry ( 199 ), particularly when held in a way that the region outside the spindle ( 140 ) is obscured by the hand as is shown in fig3 . according to the present invention , the diameter of the flared region ( 146 ) of the spindle half ( 140 ) is within 50 %, more preferably 40 %, still more preferably 30 %, and even more preferably 20 % of the diameter of the mantle ( 150 ). thus , it will be seen that the improvements presented herein are consistent with the objects of the invention for the toy described above . while the above description contains many specificities , these should not be construed as limitations on the scope of the invention , but rather as exemplifications of preferred embodiments thereof . many other variations are within the scope of the present invention . for example : the bobs need not have the same construction — for instance , only one or two of the bobs may be reversibly separable ; the spindle may have a different construction , such as not having three - fold symmetry or having a symmetry less than or greater than three - fold ; one spindle half may have a stronger grip on the weight and may have a color different from a spindle half with a weaker grip on the weight ; separated and non - separated bobs may have approximately equal areas along an axis other than the throughbore axis ; a bob may be separable into more than two partial bobs , such as three , four or more partial bobs having roughly equal mass ; etc . accordingly , it is intended that the scope of the invention be determined not by the embodiments illustrated or the physical analyses motivating the illustrated embodiments , but rather by the appended claims and their legal equivalents .
a swinging bob toy having three bobs constrained on a string , the middle bob being slideably constrained between the two end bobs , and at least one of the bobs being reversibly separable into two partial bobs . a wide variety of new tricks and maneuvers are made possible by the separability of the bobs . the two partial bobs have roughly the same weight thereby providing balanced orbits . each of the two partial bobs slides less easily along the string than a non - separated bob . the two partial bobs have roughly the same diameter along at least one axis thereby allowing visual illusions to be performed .