Occupy a square fronting on St. Mary street four hundred and sixty-seven feet, with a depth of two hundred and thirty-five feet on Gravier and Perdido streets; which is enclosed by a substantial brick wall fourteen feet high. The site was selected by James H. Caldwell, Esq., to whom New Orleans is mainly indebted for this great undertaking, as well as for many others which stand as lasting eulogiums to his memory. In 1834, the original works were put in operation. Mr. Caldwell, at this time, had the exclusive privilege of lighting the city for thirty years. His were the fourth gas works in the Union, and the first west of the mountains. The first wrought-iron roof in this country, was erected over the retort house by Mr. C., and has served as a model for all since built. The largest cast iron tank ever constructed was also put up by him. It is fifty-one feet diameter and eighteen deep, and contains over two hundred thousand gallons of water. In 1835 Mr. Caldwell disposed of this property to the Gas Light and Banking Company; who, finding the buildings insufficient, constructed them anew. The present establishment was planned and erected under the superintendence of David John Rogers, in whose care it still continues to prosper. The works, finished in 1837, cost $150,000. The whole present value is $650,000. These consist of a retort house on Gravier street, one hundred and seventeen by eighty feet, and parallel to which is the purifying house, one hundred and seventeen by fifty-two feet. On the rear is the chimney, constructed to resemble Trajan's pillar, one hundred and seven feet high; and presents a chaste specimen of classical architecture. There are three fifty feet gasometers, arranged along in the centre of the premises, capable of containing thirty thousand cubic feet each, built after the most approved workmanship, and considered to be superior to any others in this country. On Perdido street is a three story dwelling, thirty by seventy-five feet, for the workmen. The coal shed is one hundred and ninety by fifty-two feet. In addition to these are the blacksmith, carpenter, and other shops, necessary for advantageously conducting so extensive a business. The structures are all fire-proof, and every thing is kept in the neatest possible condition. In addition to the works already described, and immediately in front of them, embracing nearly another square, two more gasometers, of equal dimensions, together with the accompanying buildings, have been constructed during 1844-5. These will enable the company to transmit the gas through a distance of one hundred and fifty miles of pipe, sufficient for the accommodation of a half million of persons. The gas is extracted from Pittsburgh coal--after which the coke is sold for fuel, at about half the price that is asked for the original coal. [Illustration] THE WATER WORKS