A study of the Cervical articulations will make it clear that if a force be applied laterally to the spinous process the probable result will be a _rotation_ of the vertebra, which swings one articular process back from its fellow but leaves the other in close, but modified, contact. Thus the spinous process may appear to the left while the left articular process is fitted firmly against that of the adjacent vertebra, while those on the right are separated. Similar rotation, modified only by the difference in shape of the vertebrae, occurs in the Lumbar region. A movement applied to the spinous process might correct this condition or might complicate it according to the manner of application. But the _most direct line_ of force for correction is along a line which would pierce the separated articular processes almost in an antero-posterior direction. The Rotary approaches this very closely. It is a setting forward of the articular process against its fellow by applying a movement directly to the transverse process, which lies very close to the articular process. The great safety of the movement lies in the fact that it is impossible with any reasonable amount of force to move the transverse process too far. If the vertebra is not subluxated so as to indicate this movement, gentle attempts to use it will fail. The deceptive bent spinous process may sometimes be detected in this way. The chief objection to Rotary Nos. 1 and 2 is that the Dorsals and Lumbars cannot be adjusted in this position and the patient must rise from the bench and lie down again to have his Cervicals adjusted. This is obviated if No. 3 is used but the latter position fails to secure the perfect relaxation of muscles of Nos. 1 and 2, and is therefore recommended as an alternative only. The commonest obstacle to the use of this move is the voluntary or involuntary contraction of the neck muscles. The Hook Support, q. v., will limit this resistance by affording a sense of perfect security to the patient. If muscles are _contractured_ a slight “check” will be felt as the head reaches a certain degree of rotation, and beyond this point it will refuse to move though easily movable within the radius limited by the “check.” It is as if the head were held by an inelastic cord. It is best when contracture is present not to attempt moving the head too far but to deliver the movement with the muscles as much relaxed as possible. [Illustration: Fig. 12. The Rotary, No. 1. Ready for the movement.] Position and Palpation Place patient in position C as described under Technic of Palpation. Stand at head of bench with patient’s head supported by one knee and perhaps also by one hand. Palpate chiefly to discover the numbers of vertebrae, following a record previously made. Finish palpation with the tip of the first finger of either hand resting upon the spinous process of the vertebra to be adjusted. Placing Contact