174 
THE FAIRY-LAND OF SCIENCE. 
floor. When we land on the floor of the gallery we 
shall find ourselves in a kind of tunnel with railway 
lines laid along it and trucks laden with coal coming 
Fig. 4 6. 
Imaginary section of a coal-mine. 
towards the cage to be drawn up, while empty ones 
are running back to be loaded where the miners are 
at work. Taking lamps in our hands and keeping 
out of the way of the trucks, we will first throw the 
light on the roof, which is made of shale or hardened 
clay. We shall not have gone many yards before 
we see impressions of plants in the shale, like those in 
this specimen (Fig. 47), which was taken out of a 
coal-mine at Neath in Glamorganshire, a few days 
ago, and sent up for this lecture. You will recognize 
at once the marks of ferns (a), for they look like those 
you gather in the hedges of an ordinary country lane, 
and that long striped branch (b) does not look unlike 
a reed, and indeed it is something of this kind, as we 
