Page:Popular Science Monthly Volume 25.djvu/522

508 Secondly, when the deposits are compared, we find, as just stated, that the chimney-like form is most prominent in the Yellowstone region, while New Zealand, in that respect also, is intermediate between the park and Iceland. This more chimney-like form in the Yellowstone geysers has been explained by the statement that they contain more silica in solution, but, as already stated in the analysis already made, the percentage is usually smaller; the one exception is in a spring containing 53·76 grains of silica to the gallon of water, and it is a spring that has no conical mound. It has also been suggested that the dry air of our region may have some effect in this direction. We have no data at hand on this point; but the simpler and, to our mind, more reasonable cause is the greater age of our American region. Many of our geysers are secondary in their origin. Thus Old Faithful is a geyser that has broken out on the summit of a mound that had gradually closed up and become extinct. We can not compare the actual thicknesses of the sediments or depositions of the three regions, and, even if we could, the comparison would be apt to mislead us, as the rate of deposition in each region and among individual springs must be variable. A great antiquity, however, can certainly be accorded to all three of them. I will conclude these comparisons with a table of their elevations, including with them some of the other localities mentioned in this article:



EGISLATIVE problems are, like books, subject to vicissitudes. Solutions of the particular questions involved in single cases may seem adequate to satisfy deeply-felt wants of the public; yet it may happen that the attention of the latter is—to the scorn of the previous scientific work of years—first suddenly called to the problems by some unexpected, exciting event. It may equally well happen that a single sensational event may bring into current discussion some legislative question hitherto wholly unconsidered by science. The interest of all students is then turned for a short time to this point; its discussion occupies the saloons, fills the columns of the 