n, in safety. He gets
on into the fresh water as far, let us say, as Greenwich; and--down he
goes! Down, ma'am, to the bottom of the river, as a matter of scientific
certainty!"

Here he paused, and left Mrs. Lecount no polite alternative but to
request an explanation.

"With infinite pleasure, ma'am," said the captain, drowning in the
deepest notes of his voice the feeble treble in which Noel Vanstone paid
his compliments to Magdalen. "We will start, if you please, with a first
principle. All bodies whatever that float on the surface of the water
displace as much fluid as is equal in weight to the weight of the
bodies. Good. We have got our first principle. What do we deduce from
it? Manifestly this: That, in order to keep a vessel above water, it is
necessary to take care that the vessel and its cargo shall be of less
weight than the weight of a quantity of water--pray follow me here!--of
a quantity of water equal in bulk to that part of the vessel which
it will be safe to immerse in the water. Now, ma'am, salt-water is
specifically thirty times heavier than fresh or river water, and a
vessel in the German Ocean will not sink so deep as a vessel in the
Thames. Consequently, when we load our ship with a view to the London
market, we have (Hydrostatically speaking) three alternatives. Either we
load with one-thirtieth part less than we can carry at sea; or we take
one-thirtieth part out at the mouth of the river; or we do neither
the one nor the other, and, as I have already had the honor of
remarking--down we go! Such," said the captain, shifting the camp-stool
back again from his right hand to his left, in token that Joyce was done
with for the time being; "such, my dear madam, is the Theory of Floating
Vessels. Permit me to add, in conclusion, you are heartily welcome to
it."

"Thank you, sir," said Mrs. Lecount. "You have unintentionally saddened
me; but the information I have received is not the less precious on that
account. It is long, long ago, Mr. Bygrave, since I have heard myself
addressed in the language of science. My dear husband made me his
companion--my dear husband improved my mind as you have been trying to
improve it. Nobody has taken pains with my intellect since. Many thanks,
sir. Your kind consideration for me is not thrown away."

She sighed with a plaintive humility, and privately opened her ears to
the conversation on the other side of her.

A minute earlier she would have heard her master