By a singular coincidence, we have now the pleasure of seeing in this city the two great masses of meteoric iron which have been so often spoken of as being at Tucson, in Arizona, one of which was brought here and presented to the city by General Carleton, in November last, a notice of which, with an analysis, has already appeared in our proceedings. This mass may properly be designated as the “Carleton (Tucson) Meteoric Iron,” while the one which is destined for the Smithsonian Institution may be called the “Ainsa (Tucson) Meteoric Iron,” as it has been rendered accessible for scientific investigation by Mr. Jesus M. Ainsa, as will be seen by the following memorandum of the circumstance kindly furnished by his brother, Mr. James M. Ainsa: “This aerolite was first discovered by the early Jesuit Missionaries in the mountains called the ‘Sierra de la Madera,’ near Tucson. “In 1735, El Capitan de las Provincias del Occidente, Don Juan Bautista Anza, induced by the accounts of the science-loving Jesuits, ordered the aerolite to be removed from the mountains, with the intention of sending it to Spain. However, through the want of wagon roads and the proper means of conveyance at that time, to take it to San Blas, then the nearest port of entry, the attempt was entirely abandoned. “The aerolite was left at Tucson, where it continued to attract the attention of the scientific men who visited that country for more than a hundred years. Since the acquisition of Arizona by the United States, greater notice has been taken of this aerolite, it having been mentioned several times in the official reports of the Government agents. “By a singular coincidence, Augustin Ainsa, the great-grandson of Don Juan Bautista Anza, undertook, in 1860, to transport the aerolite and present it to the Smithsonian Institution. With great difficulty it was brought as far as the Yñigo hacienda, where it remained until May, 1863, when Jesus M. Ainsa, in his late visit to Sonora, brought it to this city, with the intention of forwarding it to the Smithsonian Institution at Washington, where it will soon be sent.” At present the mass in question lies upon the steps of the Custom House, where it has been most admirably photographed by Mr. Watkins.[2] It was said by Mr. Ainsa to weigh 1,600 pounds.