Abstract: There is disclosed well drilling apparatus which includes a mast pivotally mounted on a base so that it may be tilted about a horizontal axis in order to drill a well at a slant with respect to the vertical, a laydown device at the front side of the mast for use in moving joints of drill pipe to and from the mast, during drilling of the well or on completion of the drilling, and a tower and setback in which stands of drill pipe may be racked, together with a frame extending between the mast and tower to facilitate transfer of the stands of drill pipe between the tower and the mast during tripping of the drill string--i.e., as it is raised from the well, to permit repair or replacement of the drill bit, and then lowered back into the well to resume drilling.