Figs. 197 and 198.—Simple universal joint.
The spade holder used at the agricultural centre at Limonest is mounted on a cardan (Fig. 199).
Fig. 199.—Gardener's cylindrical spade holder. A universal joint permits movements in every direction.
The joint can be fixed by a compression screw which is easily and quickly adjusted.
Where several tools are necessary each should be complete with its own universal joint.
Other methods of terminal passive articulations are—
(1) Ball joints which have already been described in connection with the fingers and which may be applied to the wrist.
(2) Bayonet joints which are only applicable to certain artificial hands which are not subjected to any great strain.