Abstract: A measuring apparatus is provided with a stylus (30), including a column (12), a carriage (14) slidably mounted on the column (12) and a stylus carrier (32). The stylus carrier (32) carries the stylus (30) and is secured to the carriage (14). The stylus carrier (32) is provided with a bar (42) and a support (44). The support (44) is secured to one of the ends of the bar (42). The stylus (30) is secured to the support (44). The carriage (14) is provided with two supports (54, 56) arranged longitudinally on one of the sides of the slide (52), one at each of its ends. The two supports (54, 56) are in contact with one of the faces of the bar (42). A locking member (58) is formed of a lock (74) and cooperates with the other face of the bar (42). A spring (78) generates a blocking force (F) which applies the lock (74) against the bar (42). The force (F) is oriented along an axis passing between the two supports (54, 56).