THE PRINCIPLES OF BIOLOGY (2 vols issued as Vols. 2 & 3 of 'A System of Synthetic Philosophy'.

London: Williams & Norgate. 1st Eds, 'Second Thousand' . Hardcover. VG(+). 13.5 Cm x 21.5 Cm. Mauve cloth. Vol.1 (1864 but with added 1868 Appendix): viii+492, all edges marbled but top somewhat dust-darkened, marbled endpapers; only internal flaw is a number of faint & partial black oval stamps 'United University Club' on r.h. opening from half-title through to p.3, these are however fairly inoffensive due to faintness, fragmentary nature, and small size, 3 very faint small numbers top corner front blank fly; covers clean and minimally worn, v.small white spot to back, 2 gilt heraldic logos of Oxford and Cambridge centre front (the London-based club being restricted to 500 members each from these two universities), assume this is a library binding, though mauve cloth similar to standard Spencer binding; Vol.2, 1867: viii+569; condition as Vol.1 but gutter opening between pp.566/567, though has not affected tightness. front board had been detached but now so expertly repaired that this is virtually undetectable, A quite excellent set of the 2 1st edition volumes of this work, but the December 1868 Appendix to Vol.1 suggests an 1869 final (?) issue of the 'second thousand' printing. Spencer's only substantial venture into 'hard science'. Apparently extremely scarce with most listed copies being in the U.S.