In one instance a disk of gun cotton was placed in a tin which had been used in canning peas. The disk was covered with water so as to be completely immersed in it, and a second dry disk, with which to fire it, was placed upon the wet one. The face of the can resting in contact with the iron plate was originally the top of the can, through which the vegetable had been introduced, and it was consequently grooved where the cover was soldered on, and it also had an irregular drop of solder over the vent hole, the solder being raised, therefore, above the general level of the face. On firing, the can was completely volatilized or comminuted as usual, but the face of the can was reproduced in every feature and with the original values of the surface, the groove being indented in the iron, and the solder being raised above the rest of the impression. [Illustration: MAPLE LEAF REPRODUCED ON IRON PLATE.] In another instance a disk of gun cotton three inches in diameter was placed in a tin can five inches in diameter, and the can, which had a smooth bottom, placed on the face of an iron I-beam. The can was filled with water so as to just cover the gun cotton, a second dry gun cotton disk was placed on the wet disk of a primer, both being in constant contact with one side of the can, and the system detonated. As a result the can and water disappeared and the face of the beam was torn off, but on recovering the pieces and matching them it was found that not only was the smooth base of the gun cotton and the face of the can reproduced in the iron, but in the space between the gun cotton and the side of the can, occupied by the water, three distinct sets of waves were produced, having an increasing amplitude from the center proceeding outward. It is evident that many curious effects can be produced with explosive substances, and I do not doubt that useful applications will be found through a close study of the phenomena attending them. A YEAR’S PROGRESS IN THE KLONDIKE. BY PROF. ANGELO HEILPRIN. NOTE.--Acknowledgment is here made to Mr. E. A. Hegg for the use of most of the photographs accompanying this article.