and lines but that I
found time to ascertain that the ebb-stream runs at a rate of about four
knots at half-tide; and just abreast of us it flows to seaward at the
rate of about one knot at half-flood; the salt water flowing _into_ the
river along the bottom, and the fresh water continuing to flow
_outwards_ on the surface. Now, at what time do you propose to start?"

"About half-past nine to-night," answered Smellie.

Old Mildmay referred to a book by his side, and then said:

"Ah, then you will have about two hours' ebb to contend with--the last
two hours of the ebb-tide. Now let me see,"--and he produced a sheet of
paper on which were some calculations, evidently the result of his
observations whilst "Sshing." He ran over these carefully, and then
said:

"How long do you expect it will take you to cross?"

"Two hours, if we have to pull across--as I expect we shall," answered
the second lieutenant.

"Two hours!" mused the master. "Two hours! Then you'll have to make
allowance, sir, for an average set to seaward of two miles an hour all
the way across, or four miles in all."

"Very well," said Smellie. "Then to counteract that we must shape our
course for a point four miles _above_ that which marks the entrance to
the creek--must we not, Mr Hawkesley?"

"Certainly," I said; "that is quite clear."

"Then be so good as to lay that course down on the chart."

I measured off a distance of four miles with the dividers, and marked it
off _above_ the mouth of the creek; then applied the parallel ruler and
found the course.

"It is exactly south-east," said I; "and it will take us close past the
southern extremity of this small island."

"That is quite right," remarked Smellie, who had been watching me; "and
if we happen to sight the land in passing that point it will be an
assurance that, so far, we have been steering our proper course. But--
bless me,"--looking at his watch--"it is a quarter after nine. I had no
idea it was so late. Run away, Mr Hawkesley, and make your
preparations. Put on your worst suit of clothes, and throw your pea-
jacket into the boat. You may be glad to have it when we get into the
thick of that damp fog. Bring your pistols, but not your dirk; a ship's
cutlass, with which the armourer will supply you, will be much more
serviceable for the work we have in hand to-night."

I hastened away, and reached the deck again just in time to see the men
going down the side into the