HAftDWICKE'S SCIENCE- GOSSIP. 



[Jan. 1, 1869. 



rivers by the pike ; its size, also, averaging about 

 the same. Time, however, would fail me to 

 enumerate the various kiuds of fish that lived in the 

 same epoch that I did. From four or five feet in 

 length, to thousands no bigger than the common 

 stickleback, all were covered with enamel plates 

 instead of horny scales. Indeed, homy-scaled fishes 

 did not come into existence for ages afterwards. In 

 many parts of Lancashire, in the shales which overlie 

 the coal-seams, these shining enamelled plates may 

 be turned up by the thousand. The smaller fishes 

 haunted the shallower lagoons overhung by club- 

 mosses and ferns, and the dim light that broke 

 through these was often reflected from the sheeny 

 mail of Palaonisci, as they wantoned and gambolled, 

 unaware of " great fish " lying near. When the 

 muddy bottoms of these reaches and lagoons 

 became afterwards hardened into coal-shale, the 

 dead fishes lying there, whose hard covering had 

 protected them from decay, were entombed and 

 passed into a fossil state. 



But what tongue can describe the vegetable 

 wonders of the forests where I grew ? The woods 

 were so thick, and the gloom so impenetrable in 

 consequence, that it required a keen eye to make 

 out individual peculiarities. Fancy Lepidoclendra 

 four or five feet in diameter, and as much as fifty 

 or sixty feet high, and yet nothing but gigantic 

 " club-mosses " ! Their long leafy ribbons waved 

 like the leaves of the aspen, and, where these had 

 fallen off, the bark was most gracefully and geome- 

 trically reticulated from their attachment. Thirty 

 or forty different sorts of these immense club-mosses 

 existed at the same time, each characterized by 

 different leaves and bark. The gigantic Sigillaria 

 were nearly related to them, the main difference 

 being their longer leaves, straighter stems, and the 

 larger marks made on the bark. The roots, also, of 

 this latter class of trees were very peculiar, and 

 stretched through the mud on every side, seeking a 

 firm foundation for the tree to which they belonged. 

 Shooting many feet above these great club-mosses 

 were huge " mares' -tails," as easily distinguished 

 from the rest as the wavy poplar nowadays is from 

 oak and elm. These are called Catamites, and truly 

 they were extraordinary objects. You have only to 

 magnify the little "mares'-tails" growing in ditches 

 until you see them fifty and sixty (or more) feet 

 high, and you would have the best restoration of 

 these Calamites that could be imagined. There 

 were many species, characterized by fluted joints, 

 and by difference of foliage. Here and there, but 

 more sparsely scattered, were graceful tree-ferns, 

 whose former fronds had left great scars on each 

 side the trunk. The higher grounds were occupied 

 by peculiar species of pine, bearing great berries as 

 big as crab-apples. The humid morass was densely 

 covered by a thick underwood of smaller ferns, 

 which grew there in rank abundauce. The equable 



temperature, rich soil, and humid atmosphere were 

 just the needful accessories to the growth of vegeta- 

 tion of the class I have mentioned. It consequently 

 flourished at a rate of which we can form but a poor 

 idea from the present. The accumulated trees, 

 ferns, &c, were very great, and these gathered in 

 immense quantities over the entire area. I men- 

 tioned before that there was a slow sinking or sub- 

 mergence going on. Well, occasionally, the tides 

 brought up silt and strewed it over the decomposing 

 vegetation. In fact, many of the forests were 

 actually buried thus, and their trunks are frequently 

 met with standing erect in solid sandstone rock. 

 But though the covering-up of the vegetation pre- 

 vented the liberated gases from escaping, it also 

 obstructed for a time the growth of other trees. 

 The latter could not well flourish on sand-banks, and 

 so they were limited to conditions elsewhere similar 

 to those I have mentioned. But as time elapsed, 

 the old circumstances returned. Another forest 

 grew on the site of the older, to be buried up in its 

 turn. During countless ages this alternate growth 

 and covering-up went on, until in some places, as in 

 the South Wales coal-field, there are no fewer than 

 one hundred different seams of coal ! 



After this vegetation had been thus collected, 

 chemical changes began to take place. The mass 

 heated and turned black, just as a stack of hay does 

 now when it has been packed in a damp state. By- 

 and-by, it was transmuted into a pulpy condition, 

 wherein almost all traces of vegetable structure be- 

 came lost. It afterwards changed into a solid sub- 

 crystalline mass, and obtained the jetty, semi-cubical 

 character it now presents. As many of the tissues 

 of coniferous trees contain more or less of silex, 

 which is indestructible, it follows that when coal is 

 burned, this drops out of the grate as a white ash. 

 Wheu the microscope is applied to it, the peculiar 

 spiral and dotted vessels of these ancient trees are 

 plainly visible. But notice the associations which 

 cling to a piece of coal ! It represents a more solid 

 condition of carbon than is to be found in mere 

 wood. And here I should state that though various 

 conditions of fossil fuel are met with, from green 

 wood to culm and anthracite, their vegetable origin 

 is never once lost sight of; whilst chemistry steps 

 in with an easy statement of how these changes 

 occurred! The ancient vegetation of the Coal period 

 grew by virtue of the stimulus of the sun -light. 

 The heat and light induced growth, and thus even 

 a piece of coal represents so much fossil sunshine t 

 And now, when men light their fires or manufacture 

 their gas, they are but setting free the light and 

 heat of the suu which poured down on the old 

 Carboniferous forest, and were stored up by the 

 vegetation in their tissues. Nay, more, botanists 

 will tell you that the three primary colours of light 

 are sure to be developed at some time or another in 

 the history of every plant or tree— in the blue aud 



