His scientific researches were very numerous. The Royal Society Catalogue gives under the name of Faraday a list of 158 papers, published in various scientific magazines or learned Transactions. Many of these communications are doubtless short, but a short philosophical paper often represents a large amount of brain work; a score of them are the substance of his Friday evening discourses; while others are lengthy treatises, the records of long and careful investigations; and the list includes the thirty series of his "Experimental Researches in Electricity." These extended over a period of twenty-seven years, and were afterwards reprinted from the "Philosophical Transactions," and form three goodly volumes, with 3,430 numbered paragraphs--one of the most marvellous monuments of intellectual work, one of the rarest treasure-houses of newly-discovered knowledge, with which the world has ever been enriched. Faraday never published but one book in the common acceptation of the term--it was on "Chemical Manipulation,"--but there appeared another large volume of reprinted papers: and three of his courses of lectures were also published as separate small books, though not by himself. It is very tempting to linger among these 158 papers; but this is not intended as a scientific biography, and those readers who wish to make themselves better acquainted with his work will find an admirable summary of it in Professor Tyndall's "Faraday as a Discoverer." In Sections IV. and V., however, I have endeavoured to give an idea of his manner of working, and of the practical benefits that have flowed to mankind from some of his discoveries.