onless. Permit me."

So saying, the professor threw open the door giving egress to the deck,
and the whole party passed outside into the raw, nipping morning air.

With one consent the whole party made straight for the rail, and looked
downward, past the bulging sides of the ship, until their gaze rested
upon the grey sea below, the sight of which proved that the professor's
calculations could not be very far wrong. The first glance at the
far-spreading sheet of water at which they were gazing sufficed to show
that, thus far, the calm of the preceding night still continued
unbroken, for the surface was as smooth and lustrous as that of
plate-glass, save where, here and there, a steamer or two--dwindled to
the dimensions of toys--ploughed up a ripple on either bow that swept
away astern, diverging as it went, until it gradually faded and was lost
a mile away. In addition to the steamers, there were perhaps a dozen
sailing craft--colliers and fishing-smacks, mostly--in sight, the
wrinkling canvas of which, as they rolled gently upon the invisible
swell, with their bows pointing all round the compass, afforded further
confirmation, if such were needed, of the absolute stillness of the
atmosphere.

Meanwhile, Mildmay, after a single glance over the side, walked aft to
the extremity of the promenade deck, whence he levelled a pair of
powerful binoculars into the misty distance for a minute or two. Then,
apparently satisfied, he closed the glasses, and walked forward to where
von Schalckenberg was chatting to the others, and directing their
attention to such objects as happened to be in sight. As Mildmay
approached, the professor turned to him and said--

"Well, Captain, have you succeeded in identifying our position?"

"Thanks, yes," answered Mildmay. "The air is not very clear this
morning, but I have just managed to make out Spurn Point and the mouth
of the Humber in the far distance, astern. I have no doubt, therefore,
that your reckoning is absolutely correct. It is just in the single
matter of keeping a `dead reckoning' that an ocean ship has the
advantage of this craft. In the ocean the currents flow in fairly
well-defined courses, and at moderate and pretty well-known rates; it is
therefore an easy matter to make proper allowance for them. But up
aloft, here, the speed and direction of the air-currents are so
uncertain that it is impossible to take them into one's calculations;
hence it becomes necessar