Liquid sampler

A sampler, comprising a liquid sampling probe, a first element, a second element having a vertical axis for movement therealong and threadedly cooperating with said first element, said second element supporting the probe for movement therewith, one of said elements comprising a nut, reversible means for rotating said first element in a first direction and a second direction to move said second element upwardly and downwardly, respectively, along said vertical axis and to rotate said second element to first and second angular positions, respectively, keying means for limiting the rotational movement of said second element during at least part of the upward and downward movement of said second element along said axis while in said first and second angular positions, first means and second means for limiting rotational movement of said second element to said first and second angular positions, respectively, and during rotation of said first element in said second direction, and means for positioning said second means upon rotation of said second element to said second angular position and operation of said reversible means to rotate said first element in said second direction.