[10] In order to obtain this sketch, a survey was made of the delta, and from the information thus gathered a model was constructed out of clay. The dimensions of the delta are about one thousand by seven hundred feet. [11] The bottom of the cañon at this point is between four and five thousand feet below the flat surfaces in the foreground--a sheer descent of nearly a mile. * * * * * M. Henri Bourget, of the Toulouse (France) Observatory, has called attention in Nature to a common phenomenon which he believes has not been mentioned in any scientific book. If one end of a bar of metal is heated, but not enough to make the other end too hot to be held in the hand, and then suddenly cooled, the temperature of the other end will rise till the hand can not bear it. All workmen who have occasion to handle and heat pieces of metal, he says, know this. DEATH GULCH, A NATURAL BEAR-TRAP. BY T.A. JAGGAR, JR., PH.D. Cases of asphyxiation by gas have been very frequently reported of late years, and we commonly associate with such reports the idea of a second-rate hotel and an unsophisticated countryman who blows out the gas. Such incidents we connect with the supercivilization of the nineteenth century, but it is none the less true that Nature furnishes similar accidents, and that in regions far remote from the haunts of men. In the heart of the Rocky Mountains of Wyoming, unknown to either the tourist or the trapper, there is a natural hostelry for the wild inhabitants of the forest, where, with food, drink, and shelter all in sight, the poor creatures are tempted one after another into a bath of invisible poisonous vapor, where they sink down to add their bones to the fossil records of an interminable list of similar tragedies, dating back to a period long preceding the records of human history. It was the writer's privilege, as a member of the expedition of the United States Geological Survey of the Yellowstone Park, under the direction of Mr. Arnold Hague, to visit and for the first time to photograph this remarkable locality. A similar visit was last made by members of the survey in the summer of 1888, and an account of the discovery of Death Gulch was published in Science (February 15, 1889) under the title A Deadly Gas Spring in the Yellowstone Park, by Mr. Walter Harvey Weed. The following extracts from Mr. Weed's paper indicate concisely the general character of the gulch, and the description of the death-trap as it then appeared offers interesting material for comparison with its condition as observed in the summer of 1897.