delayed until the publication of the second edition of the Museum Catalogue, which it is intended to issue as soon as the printing of the general catalogue is complete, as this would considerably abridge the labour of preparing the supplement. I have already, in the paper read at Paris last year, expressed my opinion that the Museum Catalogue, when complete, will afford the only practicable basis for the far more important and extensive undertaking of a universal catalogue. Success in such an undertaking would indeed be the triumph of successful co-operation, but when the enormous difficulties of establishing co-operation among the libraries, not of a single country only, but of the whole civilised world, are considered, the difficulty may well appear insuperable, until the various countries shall have approximated much more nearly to the condition of a single country than they have done as yet. Such, however, is the unquestionable tendency of the times, depending upon causes which, so far as can be foreseen, appear likely to operate with augmented intensity, and this movement may proceed far enough to eventually bring with it the universal catalogue along with the universal language, the universal coin, and the universal stamp. Till within a short time ago I had reason to believe that a co-operative catalogue, which I myself proposed several years ago, was on the point of being undertaken. Some may remember that I once read a paper at a London monthly meeting on the preparation of an index of subjects to the Royal Society's catalogue of scientific papers, without which that great store of information is in a measure useless. This paper was re-published in _Nature_, the idea was taken up by Mr. Collins of Edgbaston, the compiler of the indexes to Herbert Spencer's works, and a few weeks ago success seemed about to crown his efforts. I now learn with regret that the scientific men who met in conclave on the project have not been able to agree, and I suppose it will remain in abeyance until some Hercules-Littré arises and does it by himself.