is defined by a projecting plate 26 having a guiding hole 28 for a casing not shown the drilling machine 24 is carried by an upper carriage 30 see fig2 and 10 u shaped guide edge portions 30 39 thereof engaging displaceably around the derrick 39 s 16 longitudinal guidance edges 32 which for the purpose of guiding likewise may have a horizontal u shaped cross section in respect of a lower carriage 34 the vertical edges 34 39 thereof engaging displaceably into said u shaped guidance edges 32 39 the lower carriage 34 carries a catcher means in the form of a clamp or clip generally denoted at 36 the clip 36 which appears clearest from fig8 and 9 on a relatively large scale has a fixed jaw 38 and a movable jaw 40 hinged thereto and pivotable about the vertical axis 42 of the hinge a double acting hydraulic piston cylinder 44 turning the movable jaw 40 between a closed catching position fig8 and a more or less open position of readiness release position taken by the clip when it from above is threaded down onto the upper end portion of a casing fig9 on the top of the derrick 16 a small winch 46 is disposed the winch i a being used for easing a base pipe a tubular.