the author of a mathematical dictionary in 1702, as a different person from J. Raphson, F. R. S., who wrote at least four books of a contemporary date? He will be wrong if he do; but nothing except an examination of the lists of the Royal Society will enable him to be certain. Out of such trifles as these spring many mistakes, such as can hardly be avoided, except by knowledge beyond what the books themselves can give. And as to the books themselves, nothing short of a studied examination will show the difference between a perfect and imperfect volume. A folio collection of astrologers (1533) which has at the end of the contents 'Postremo Othonis Brunfelsii . . . . .' has the work of this Otho first instead of last. We have seen many volumes which were really perfect marked imperfect, on the assumption that the contents and their table of contents must tally in order, as in a modern work. But there is a source of confusion about very old books which has not been much noted hitherto, and which promises to give rise to much inquiry. The copies of the same edition of the same work do not agree with one another. Sometimes there is a discreprepancy of this kind. The impression seems to have been printed without any of the large and ornamented capital letters: these were stamped into a part of the impression afterwards, leaving the remaining copies with empty spaces for those who preferred to have these letters wholly the work of the illuminator. Sometimes different headings were put in to suit dif[17]ferent tastes. For example, we have before us the first printed edition of the Alphonsine Tables, Venice, 1483. The heading or title is in red ink as follows,—'Alfontii regis castelle illustrissimi celestium motuum tabule: . . . . . .' Hain's description (Repert. Bibliogr.) shows that he had inspected a counterpart of this. But Captain Smyth (Cycle, &c., vol. ii. p.215) has given a facsimile from another copy of this same edition, by which it appears that the heading is in black ink, having a picture of some astronom-
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