other writers may have investigated the subject, or, consequently, how far his observations are in accordance with theirs. Multiply my little embarrassment by several hundred thousand, and you will have some idea of the amount of ignorance which the classified index suggested by Mr. Bailey would enlighten. We may well believe that the only objection he has heard alleged is the magnitude of the undertaking, and must sympathise with his conviction that, granting this, it still ought not to be put aside, merely because it is difficult. I hope to point out, however, that so far as concerns the scientific papers, to which alone Mr. Bailey's proposal relates, the difficulty has been over-estimated, that the literary compilation need encounter no serious obstacle, and that the foundation might be laid in a short time by a single competent workman, such as Mr. Bailey himself. Of an index to literary papers I shall speak subsequently; and, there, I must acknowledge, the difficulties are much more formidable. But as regards scientific papers, it appears to me that the only considerable impediment is the financial. When the others are overcome, then, and not till then, we shall be in a favourable position for overcoming this also. The reason why the formation of a classified index to scientific papers is comparatively easy, is that the groundwork has been already provided by the alphabetical index of the Royal Society. We have the titles of all scientific papers from 1800 to 1865 before us, and shall soon have them to
