PREFACE. xvii
MSS. (2156). It contains the first book and part of the second of the Communia Mathematicac. Attention was called to it both by Brewer and by Charles, and oceasional references to it have been made in the present edition.
Yet a third fragment is the elementary work on Greek grammar in the possession of Corpus Christi College, Oxford, which was sent to the Bodleian for my perusal. An imperfect copy, in seventeenth cen- tury handwriting, apparently made from the Corpus MS., is contamed among the Baconian MSS. of University College.
Bacon's commentary on the Seeretum Scecretorum (Tanner MSS, 116) has also been examined, It throws light on the astrological side of his work.
Among the books consulted for this edition, far the most important are those of Professors Brewer and Emile Charles, already spoken of. It is unfortunate that two such assiduous and able investigators should have worked simultancously and without communication. Several not unimportant errors might have been avoiled, had either of them known of the other's work. Charles had a far more extensive knowledge than Brewer of Bacon’s unpublished works; and his extracts from them are so copious as to render it desirable that his monograph, which has already become extremely rare, should be republished. He makes, however, the erroneous statement (p. 62) that the missing portion of the Opus Jajus (here printed for the first time) had been published in Dublin; and he does not appreciate the distinction, sa clearly demonstrated by Professor Brewer, between the Opus fertium (which is at once an introduction and a supple-
ment to the Ops JAfajus), and the far vaster Sersptame VOL. I. b
