Abstract: A probe arrangement and set of tubes for a penetrometer. The probe is formed from a sleeve and a point which comprises a central part and a peripheral part which are connected by a cotter pin. The set of tubes comprises a central rod, which is attached to the central part of the point, and two concentric tubes around the rod. The arrangement may be used for making four independent measurements. The peripheral part of the point is connected to the sleeve in such manner that on holding the outer tube and applying a driving force to the central rod, the cotter pin shears and the central part of the point travels downwards so that hard ground may be studied.

Abstract: A housing adjacent the anvil of a penetrometer has a pair of parallel upright guides on one of which is slideable a first counterweight and on the other of which slides a second counterweight and a slide underneath this second counterweight. The first counterweight weighs more than the slide but less than the slide and second counterweight together. A chain passes over a sprocket at the top of the housing and has one end secured to the first counterweight and another end to the slide. An abutment on the second counterweight engages over a follower on the anvil so that as the anvil goes up and down the second counterweight follows it. During normal descent of the anvil and second counterweight a ratchet engaging the wheel prevents return rotation of this wheel, but once the second counterweight is all the way at the bottom of its guide the ratchet is pulled back. Upward movement of this second counterweight from this position through a distance equal to one tube length reactuates the ratchet.

Abstract: A penetrometer frame for mounting on, for example, a truck and comprising a fixed part provided with slides which guide a moving part in the form of a frame which itself serves as a guide for a driving hammer and which may be raised or lowered by two hydraulic rams. The fixed part of the frame is pivoted on a platform about a horizontal pivot offset from the point where tubes are inserted or removed. The arrangement is such that extending the rams causes the penetrometer frame to pivot and allows access to the position at which tubes are inserted or removed.