the second embodiment of fig2 b has a tapered thickness as described in connection with the embodiment of fig2 a and as best shown in fig1 is tapered throughout lowermost portion 32 the somewhat longe inclined slot 40 as compared to the radial slot 36 of fig2 a removes more material from lowermost portion 32 of core catcher 10 and therefore proportionally allows a greater degree of volumetric compression of lowermost portion 32 whereas fig2 a and 2b are related to a first and second embodiment of the invention respectively which is reusable namely reusable in repeated operations without replacing core catcher 10 the third and fourth embodiments of fig2 c and 2d respectively are nonreusable in the embodiments of fig2 c and 2d the nonreusable core catcher differs again in the design of its lowermost portion 32 and is generally characterized by being irreversibly crushable the circumference and diameter of the third and fourth embodiments of fig2 c and 2d can thus be decreased substantially without regard to the design and geometry of lowermost portion 32 of core catcher 10 in other words the degree of diametric compression of lowermost portion 32 of the third and fourth embodiments of fig2 c and 2d will in the first approximation be determined by the compressibility of the adjacent core and.