voice that spoke of nerves near to the breaking point. Instantly Cleek
was serious. He reached out a hand and laid it upon the young man's
shoulder. Merriton was trembling, but he steadied under the grip, just
as it was meant that he should.

"See here," Cleek said, bluntly, "you oughtn't to work yourself up into
such a state. It's not good for you; you'll go all to pieces one of these
days. Those flames, eh? Why I thought any one knew enough about natural
phenomena to answer that question. But it seems I'm wrong. Those flames
are nothing more nor less than marsh gas, Sir Nigel, evolved from the
decomposition of vegetation, and therefore only found in swampy regions
such as this. Whew! and to think that here is a community that has been
bowing down to these things as symbols from another world!"

"Marsh gas, Mr.--"

"Headland, please. It is wiser, and will help better to remember when the
necessity arises," returned Cleek, with a smile. "Yes, that is all they
are--the outcome of marsh gas."

"But what _is_ marsh gas, Mr.--Headland?" Merriton's voice was still
strained.

Cleek motioned to a chair.

"Better sit down to it, my young friend," he said, gently. "Because, to
one who isn't interested, it is an extremely dull subject. However, it is
better that you should know--as you don't seem to have learnt it at
school. Here goes: marsh gas, or methane as it is sometimes called, is
the first of the group of hydrocarbons known as paraffins. Whether that