In October, 1855, Mr. William B. Astor, son of the founder, conveyed to the trustees the lot, eighty feet front by one hundred and twenty deep, adjoining the library on the north, and proceeded to erect upon it an addition similar in all respects to the existing structure, the library thus enlarged being opened September 1, 1859, with one hundred and ten thousand volumes on its shelves.  The addition led to a rearrangement of the material, the old hall being devoted to science and the industrial arts, and the new to history and general literature.  In 1866 Mr. Astor further signified his interest in the library by a gift of fifty thousand dollars, twenty thousand dollars of it to be expended in the purchase of books, and on his death in 1875 left it a bequest of two hundred and forty-nine thousand dollars.  In 1879 Mr. John Jacob Astor, grandson of the founder, added to this enduring monument of his family by building a second addition, seventy-five feet front and one hundred and twenty feet deep, on the lot adjoining on the north, making the entire building two hundred feet front by one hundred deep.  At the same time an additional story was placed on the Middle Hall, and a new entrance and stairway constructed.  The enlarged building, the present Astor Library, was opened in October, 1881, with two hundred thousand volumes and a shelf-capacity of three hundred thousand.  Its present contents are estimated at two hundred and twenty thousand volumes, exclusive of pamphlets.  The shelves are ranged in alcoves extending around the sides of the three main halls and subdivided into sections of six shelves each, each section being designated by a numeral.  Each shelf is designated by a letter of the alphabet, beginning at the bottom with A. The alcoves have no distinguishing mark, the books being arranged therein by subjects which the distributing librarian is expected to carry in his mind.  The first catalogue, in four volumes, was compiled by Dr. Cogswell and printed in 1861.  This was followed in 1866 by an index of subjects from the same hand.  Recently a catalogue in continuation of Dr. Cogswell’s, bringing the work down to the end of 1880, has been prepared, and is being printed at the Riverside Press, Boston.  The current card catalogue is arranged on the dictionary plan, giving author and subject under one alphabet.  Opposite each title is written the number of the alcove and the letter designating the shelf.  By the regulations the reader is required to find the title of the book desired in the catalogue, write it with the number and letter on a slip of paper provided for the purpose, and give it to the distributing librarian, who despatches one of his boy Mercuries to the shelf designated for the work.  More often than not, however, the reader asks directly for the book desired, without consulting the catalogue, and it is rarely that the librarian cannot from memory direct his messenger to the section and shelf containing it.  In the matter of theft and mutilation of books