a pinion 178 a situated at the distal end of the shaft 158 a of the second pivoting system that is engaged with the going train and that therefore makes it possible to bring the torque from the energy source to one of the inputs in this case the first plate 202 a of the differential 200 the other input of the differential 200 does not receive the torque coming from the energy source given that as mentioned above the differential 200 takes the average of the rotations received at those inputs and the rotations due to the movement of the support 64 cancel each other out the output of the differential 200 i e the satellite carrier 208 therefore only transmits a rotation induced by the torque provided by the energy source the satellite carrier 208 is kinematically connected to the escapement as can particularly be seen in fig4 using a shaft 240 provided on the one hand with an escapement pinion 242 meshing with the satellite carrier 208 and receiving the escapement wheel 244 on the other hand the shaft 240 passes through the support 64 such that the adjusting organ 246 and the pallet 248 are situated on the upper side of the bridge and are situated at the periphery of the chassis so as to be visible by a user to improve the compactness of the system the escapement is of the angle type i e the axes of the adjusting organ 246 the palette and the escapement wheel are not aligned this makes it possible to bring the axis of the adjusting organ and that of the escapement wheel closer together it may also be noted that the half.