a gradual change, and recognise the silent operations of nature in ages never counted by man.  According to the popular theory, the earth must have been sixty times as large as its present size, and have cooled to its present dimensions, retaining still, in its unfathomable bowels, a burning heat.  The conclusions of geologists, after long and patient examination, are, that certain rocks mark the age of the world—­that, in fact, the crust of the globe consists of a certain number of strata, each belonging to a certain era, as the rings of a tree tell its years of growth.  The more they test this theory, the more certain are they that the history of our globe may be accurately read in the strata which compose its crust.  “A granitic crust, containing vast and profound oceans, as is proved by the extent and thickness of the earliest strata, was the infant condition of the earth.  Points of unconformableness in the overlying aqueous rocks, connected with protrusions of granites, and other similar presentments of the internal igneous mass, such as trap and basalt, mark the conclusions of subsequent sections in this grand tale.  Dates, such as chronologists never dreamed of—­compared with which, those of Egypt’s dynasties are as the latter to a child’s reckoning of its birthdays—­have thus been presented to the now living generation, in connexion with the history of our planet."[5] These changing masses have been discovered with remains of organic life wrapped in their particles, each mass enclosing a petrified museum of the life that flourished while it was in course of formation:  thus not only have we distinct proof of extinct forms of animal and vegetable life, but we are also able to assign the dates of their existence.

The most easterly room of the northern mineral and fossil gallery, is that to which the visitor’s attention will be first directed.  In this room, as in the next three, the table cases are devoted to the minerals; and the wall cases, along the southern side of the gallery, are filled with

Fossil vegetables.

The wall cases of this room contain the various strata which have traces of vegetable life.  The earliest vegetable life of which the geologist has found fossil remains is in the form of sea-weeds, specimens of which the visitor will notice in case 1.  The grand harmony of the world’s development is shown in this adaptation of the earliest vegetable life to that of the earliest animal life—­the polypus drawing its sustenance from the sea-weed.  In the next three cases the visitor will notice various remains of fossil ferns (in clay slate) and horse-tails, all indicating the former high temperature and moisture of the localities in which they are found, since they are of large proportions, and it is observable that these plants grow in bulk according as they near the tropics.  That the ferns and club mosses have diminished with the decrease of temperature of the