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twenty miles, regarding one minute on the latitude scale as being a mile. Sonya, recruited in her linguistic
capacity, confirmed that the (to Grimes) meaningless squiggles alongside the dot on the chart did translate
to  Drarg.
The trouble was that the unlucky shot that had immobilized the airship s engines had also immobilized
her generator. There were batteries but they were flat. (During a revolution quite important matters tend
to be neglected.) The radio telephone was, in consequence, quite useless. Had there been power it
would have been possible to raise the party on the island, to get them to send the pinnace to pick them
up when the aircraft was ditched, or, even, to tow them in.
 At least we re drifting away from the land, said Farrell, looking on the bright side.  I don t think
that we should be too popular if we came down ashore. He added, rather petulantly,  Apart from
anything else, my orders were that there was to be no intervention ... He implied that all the killing had
been quite unnecessary.
 Self-defense, Grimes told him.  Not intervention. But if you ever make it back to Lindisfarne Base,
James, you can tell the Admiral that it was the wicked Rim Worlders who played hell with a big stick.
 We re all in this, Commodore, said Farrell stiffly.  And this expedition is under my command, after
all.
 This is no time for inessentials, snapped Sonya. She straightened up from the chart, which she had
been studying.  As I see it, they ll sight us from the island, and assume that we re just one of the rebel
patrol craft. They might try to intercept us, trying to find out what s happened to us. On the other hand
...
 On the other hand, contributed Farrell,  my bright Exec does everything by the book. He ll insist
on getting direct orders from Lindisfarne before he does anything.
 How does this thing work? asked Sonya.  Can you do anything, John? The way that you were
talking earlier you conveyed the impression that you knew something about airships.
Grimes prowled through the control compartment like a big cat in a small cupboard. He complained,
 If I had power, I could get someplace. This wheel here, abaft the binnacle, is obviously for steering. This
other wheel, with what looks like a crude altimeter above it, will be for the altitude coxswain. The first
actuates a vertical steering surface, the rudder. The second actuates the horizontal control surfaces, for
aerodynamic lift ...
 I thought that in an airship you dumped ballast or valved gas if you wanted to go up or down,  said
Sonya.
 You can do that, too. Grimes indicated toggled cords that ran down into the control room from
above.  These, I think, open valves if you pull them. So we can come down. He added grimly,  And
we ve plenty of ballast to throw out if we want to get upstairs in a hurry.
 Then what s all the bellyaching about? asked Farrell.  We can control our altitude by either of two
ways, and we can steer. If the rudder s not working we can soon fix it
Grimes looked at him coldly.  Commander Farrell, he said at last,  there is one helluva difference
between a free balloon and a dirigible balloon. This brute, with no propulsive power, is a free balloon.
He paused while he sought for and found an analogy.  She s like " a surface ship, broken down, drifting
wherever wind and current take her. The surface ship is part of the current if she has neither sails nor
engines. A balloon is part of the wind. We can wiggle our rudder as much as we like and it will have no
effect whatsoever ... Once again he tried to find a seamanlike analogy and found something more
important. He whispered,  Riverhead ...
 Riverhead? echoed Farrell.  What s that, Commodore?
 Shut up, James, murmured Sonya.  Let the man think.
Grimes was thinking, and remembering. During his spell of command of Sonya Winneck, on
Aquarius, he had been faced with an occasional knotty problem. One such had been the delivery of a
consignment of earth-moving machinery to Riverhead, a new port miles inland equipment which was to
be used for the excavation of a swinging basin off the wharfage. The channel was deep enough but at
its upper end it was not as wide as Sonya Winneck was long. However, everything had been arranged
nicely. Grimes was to come alongside, discharge his cargo and then, with the aid of a tug, proceed stern
first down river until he had room to swing in Carradine s Reach. Unfortunately the tug had suffered a
major breakdown so that Sonya Winneck, if she waited for the repairs to be completed, would be at
least ten days, idle, alongside at the new wharf.
Grimes had decided not to wait and had successfully dredged down river on the ebb. He said slowly,
 Yes, I think we could dredge ...
 Dredge? asked Farrell.
Grimes decided that he would explain. People obey orders much more cheerfully when they know
that what they are being told to do makes sense. He said,  Yes, I ve done it before, but in a surface ship.
I had to proceed five miles down a narrow channel, stern first ...
 But you had engines?
 Yes, I had engines, but I didn t use them. I couldn t use them. Very few surface ships, only
specialized vessels, will steer when going astern. The rudder, you see, must be in the screw race. You
must have that motion of water past and around the rudder from forward to aft ...
 The dredging technique is simple enough. You put an anchor on the bottom, not enough chain out so
that it holds, but just enough so that it acts as a drag, keeping your head up into the current. You re still [ Pobierz całość w formacie PDF ]