This idea has long been working in the minds of scholars, and all who have had occasion to follow out any special subject. I have a right to speak of it, for I long ago attempted to supply the want of indexes in some small measure for my own need. I had a very complete set of the “American Journal of the Medical Sciences;” an entire set of the “North American Review,” and many volumes of the reprints of the three leading British quarterlies. Of what use were they to me without general indexes? I looked them all through carefully and made classified lists of all the articles I thought I should most care to read. But they soon outgrew my lists. The “North American Review” kept filling up shelf after shelf, rich in articles which I often wanted to consult, but what a labor to find them, until the index of Mr. Gushing, published a few months since, made the contents of these hundred and twenty volumes as easily accessible as the words in a dictionary! I had a copy of good Dr. Abraham Rees's Cyclopaedia, a treasure-house to my boyhood which has not lost its value for me in later years. But where to look for what I wanted? I wished to know, for instance, what Dr. Burney had to say about singing. Who would have looked for it under the Italian word cantare? I was curious to learn something of the etchings of Rembrandt, and where should I find it but under the head “Low Countries, Engravers of the,”--an elaborate and most valuable article of a hundred double-columned close-printed quarto pages, to which no reference, even, is made under the title Rembrandt. There was nothing to be done, if I wanted to know where that which I specially cared for was to be found in my Rees's Cyclopaedia, but to look over every page of its forty-one quarto volumes and make out a brief list of matters of interest which I could not find by their titles, and this I did, at no small expense of time and trouble.