apparatus application_number US 50881483 A description referring now first to fig1 a 1e of the drawings the apparatus includes an upper tubular body member 10 of circular horizontal cross sections having a bore 11 downwardly therethrough and having an internally threaded socket 12 at the upper end of bore 11 by means of which the apparatus may be connected to the lower end of an upper drill string portion the upper drill string portion to which the apparatus is connected at socket 12 will usually extend to the surface the internal drill string pressure may be controlled therein by suitable pumps or other facilities at the surface not shown the surface equipment for this purpose is conventional and further explanation thereof is not necessary an upper sleeve 13 is disposed within body member 10 between upwardly facing interior shoulder 14 thereof and a spiralox snap ring 15 sleeve 13 is outwardly relieved below its upper end at 16 to provide an annular space 16a therearound within body member 10 a port 17 enlarged at its upper end houses a check valve 18 and a plug 19 both screwed into threads around the enlarged portion of port 17 the port 17 is reduced at its lower end 20 and turns outwardly at 21 to communicate with the space 16a formed by relief 16 piston sleeve 24 spaced uniformly inwardly from sleeve 13 has upper outwardly projecting portion 25 around which an o ring 26 and wiper ring 27 are disposed in suitable grooves a lower accumulator end ring 28 having o ring seal 29 in a groove therearound is screwed into bore 11.