The history of the origin of public libraries is simple. Very few persons who possessed a desire to own books of great value could, in early times, afford to gratify their wish, owing either to want of the necessary means, or the very great scarcity of many works of intrinsic value. Before the invention of the great art of printing it is well known that all communicated learning was, of necessity, confined to manuscript on vellum. And that the only mode of repeating books was by transcription. The number of copies being extremely limited, it became necessary to have public places at each of which a copy might be placed for the use of those who desired to read, and as that number was in those days limited also, it was customary for some man of learning to read aloud to an audience.

These folios of manuscript, in time, accumulated to thousands, and the places of their deposit became institutions, and received the name of librarium. The term “librarian,” however, was applied in those days to the transcriber of books (librarius), rather than to the custodian, the latter officer being entitled custos librariarum, and who was nothing more than a janitor.

The enormous impetus given to education by the invention of printing, although it multiplied copies of books to such an extent as to render them cheap enough to become the property of individuals, still public libraries suffered no diminution, and the very increase of the draught seemed to promote the thirst for information, especially in that class in whom a taste for reading was controlled by a limit of means to become possessed of the necessary books. And although in our day the newspaper, the journal, and the serial, do much to disseminate knowledge among the millions, yet are libraries as much an institution of positive necessity as ever; for, in fact they whet the appetite for reading, and the brief paragraphs and condensed essays editorial are but so many stimulants to more extensive acquisitions of information. The taste grows, and the patronage of libraries increases, and such a progress must continue and enlarge whilst the mind of man lives to accomplish the task set by Him in whose likeness the favored being is made.

The history of libraries is one of great interest to the lover of mental progress and the active civilization of our race, and might well call out the most industrious efforts of learned writers to do it justice. However, our business just now is with a local event—the inauguration of a new building by a most popular institution, the Mercantile Library of this city, which took place on the 15th of the past month, in the presence of a large and intellectual number of visitors of both sexes.

The rise and progress of this admirable institution is interesting. Started in 1822 in a small second-story room, with few books and fewer members, pinched to pay the rent of $150 per annum, by degrees it gained vigor and steadily advanced to its present position, occupying now a building admirable in all the arrangements of room, light, heat, and ventilation.

This spacious building, occupying a prominent position on Tenth street, north of Chestnut, in this city, was purchased and fitted up at a cost of a quarter of a million dollars, and possesses a choice collection of books amounting to fifty-two thousand volumes, besides a well supplied news room, where will be found a great variety of journals from all parts of the civilized world, together with magazines, reviews, quarterlies, and annuals in abundance. The ladies having a separate department to themselves, unapproachable by the masculines.

The arrangement by which the reading rooms have been studiously kept in the rear of the building out of the reach of street disturbances, is one which gives it a great advantage over the public libraries of most other cities.

There is a well furnished chess room for the lovers of that mental game, and conversation, waiting and other rooms requisite to perfectly complete a truly desirable city institution.

We understand that the membership exceeds fifty thousand, and judging from what has been done, there is no reason to doubt its ultimately doubling that number in so large a city as this.

Artificial Stone.—At the recent meeting of the Polytechnic Association of the American Institute, Mr. Thomas Hodgson exhibited and explained two methods of manufacturing and moulding artificial stone ornaments, blocks, etc., for buildings. One of these is prepared by treating lime with a solution of four ounces of oxalic acid in a gallon of water, thus producing an oxalate of lime, which is mixed with from two to four times its weight of sand. In this condition the material is a moist, friable powder. It is then moulded to the required form in Plaster-of-Paris moulds, removed from the latter, and suffered to dry. It is then preferably placed in a bath of dilute oxalic acid, which causes it to harden throughout, after which it is ready for use. In making the other variety, the inventor treats the oxalate of lime with a solution of silicate of potash, thus bringing it to a semi-fluid condition, whereupon it is poured into moulds and suffered to indurate.

Dr. Van der Weyde said that the oxalate of lime, being one of the most insoluble substances known in chemistry, its employment in the fabrication of artificial stone was a lucky thought. The use of potash and soda compounds for such purposes had been extensively attempted with very poor results, but the oxalate of lime was free from objections which hold good against such compounds.—Railroad and Mining Register.

The New Treasury Building, at Washington, D. C., is now completed. This addition or north wing of the Treasury building is 65 by 195 feet, and occupies the site of the old State Department. The entire Treasury building covers an area of 520 by 278 feet, that is 144,550 square feet, or three acres and a half, including two large courts. On the eastern side of the building is a colonnade of thirty pillars, extending 336 feet north and south. On each of the other sides is a portico, each shaft of the columns of which is a monolith or single block of stone, 32 feet in height, and 4 feet 6 inches in diameter, that is 14 feet in circumference. The buttress caps, which partially inclose the steps of the porticoes, are single slabs of granite, 20 feet square by 2 feet thick. The granite was quarried on Dix’s island, off the coast of Maine, and the larger slabs were taken to Washington in the rough, and there dressed. Fronting the north entrance is a fountain, the base of which is 12 feet in diameter, and the height 5 feet. It was cut from a single block of granite.