Its shape is irregular, but in general it is that of a flattened elongated slab, having a length of four feet one inch and an average breadth of about eighteen inches; its thickness is irregular, varying from two to five inches. It has evidently been long used as an anvil, having been partly buried in the ground in an upright position, having a flat face of about four inches square on the top, with two holes drilled in the projecting edge for adding to the convenience of its use as a blacksmith’s anvil. The mass is now placed in the Mayor’s office, it having been deemed inadvisable to expose it on the Plaza, as desired by the donor, on account of its liability to rust in the damp atmosphere of San Francisco, and the difficulty of securing it from injury by careless or mischievous handling. Professor Brush remarks that “the composition of this meteorite corresponds very closely with that of _another_ meteoric iron from Tucson” discovered by Mr. Bartlett and analyzed by Professor J. Lawrence Smith. A comparison of the analyses of Professors Brush and Smith and a reference to Mr. Bartlett’s work seem to render it highly probable, to say the least, that the two analyses were of pieces cut from the same mass. In this connection I will add to General Carleton’s quotation from Mr. Bartlett’s book a few lines which complete what is said in regard to the meteorites seen by him at Tucson. Mr. Bartlett adds, after stating that the mass was found about twenty miles distant towards Tubac and about eight miles from the road, “where we were told are many larger masses. The annexed drawing gives the appearance of this singular mass. There is another large mass within the garrison grounds, of which I did not take a sketch. With much labor Dr. Webb broke off a fragment of this meteorite, for the purpose of analysis.” The wood cut which Mr. Bartlett gives of the meteoric iron, which he notices as having been used as an anvil, shows at once, as does also the description, that, contrary to General Carleton’s idea, this mass and the one which is now in San Francisco, are not the same. The mass figured by Mr. Bartlett is of a very peculiar shape, well adapting it to use as a common blacksmith’s anvil, as it has a broad, flat top, and is supported by two legs.