Page:Popular Science Monthly Volume 51.djvu/171

Rh assembled together firmly, and the experiment of separating them was rewarded with prompt success. On account of the magnitude of the large gun it had been impossible to heat it with perfect uniformity from without, while no such difficulty was experienced with the much smaller dummy. A series of measurements upon the large gun revealed the fact that during the first experiment it had become warped, and the diameter of the tube had been diminished in varying degrees at different parts.

Whether such results as these would have been brought about had the materials been of the best quality of crucible steel instead of open-hearth steel can not be answered positively. The larger the gun the greater is the danger of such mishaps. It is left to coming experience to determine which is to be the steel of the future for gun construction.



R. RICHARD G. WILLOUGHBY is a mining prospector and "promoter," resident in Juneau, Alaska, a man whose vocation enables him to see some wonderful things. In June, 1888, according to his statement, Mr. Willoughby beheld an extraordinary mirage from the surface of the Muir Glacier. It was the apparition of a great city of tall houses of brick and stone, plainly shown in the air under the influence of some powerful refraction. Behind the city was a river in which shipping was faintly shown. In the foreground the leafless branches of tall elm trees were clearly traceable. In the center of the city was a large edifice with several towers, and on some of these towers the presence of scaffolding showed that building was still going on. This mirage was seen by him several times from year to year, and on the unfinished building the stages in the process of erection each season could be distinctly followed.

Mr. Willoughby sent to San Francisco and secured a camera with a number of highly sensitized plates of the usual commercial sort in order to photograph the apparition. This he succeeded in doing but once successfully. The necessary exposure was a very long one, because of the unsubstantiality of the object. The one negative, however, gave a fairly clear print. Copies were at once made, and R. G. Willoughby's Silent City (seventy-five cents each) was added to the wonders of Alaska. I present herewith a copy of this picture bought by me in Sitka in 1896. The picture is not quite the same as the original edition of 1888.