room behind the pantry, a room that exists solely for maintenance of the galvanick lucipher and the storage of its parts and supplies. The heart of the device is a hand-blown spherical glass jar comparable in volume to a gallon jug. Ghnxh, who suffers from a pretty advanced case of either hypothermia or Parkinson's, maneuvers a glass funnel into the neck of the jar. Then he wrestles a glass carboy from a shelf. The carboy, labeled AQUA REGIA, is filled with a fulminant orange liquid. He removes its glass stopper, hugs it, and heaves it over so that the orange fluid begins to glug out into the funnel and thence into the jar. Where it splashes out onto the tabletop, something very much like smoke curls up as it eats holes just like the thousands of other holes already there. The fumes get into Waterhouse's lungs; they are astoundingly corrosive. He staggers out of the room for a while.
When he ventures back, he finds Ghnxh whittling an electrode from an ingot of pure carbon. The jar of aqua regia has been capped off now, and a variety of anodes, cathodes, and other working substances are suspended in it, held in place by clamps of hammered gold. Thick wires, in insulating sheathes of hand-knit asbestos, twist out of the jar and into the business end of the galvanick lucipher: a copper salad bowl whose mouth is closed off by a Fresnel lens like the ones on a lighthouse. When Ghnxh gets his carbon whittled to just the right size and shape, he fits it into a little hatch in the side of this bowl, and casually throws a Frankensteinian blade switch. A spark pops across the contacts like a firecracker.
For a moment, Waterhouse thinks that one wall of the building has collapsed, exposing them to the direct light of the sun. But Ghnxh has simply turned on the galvanick lucipher, which soon becomes about ten times brighter, as Ghnxh adjusts a bronze thumbscrew. Crushed with shame, Waterhouse puts his Navy flashlight back into its prissy little belt holster, and precedes Ghnxh out of the room, the galvanick lucipher casting palpable warmth on the back of his neck. 'We've got about two hours before she goes dead on us,' Ghnxh says significantly.
They work out a
Half of the castle has, at one point or another, been burned down by a combination of Barbary corsairs, lightning bolts, Napoleon, and smoking in bed. The Barbary corsairs did the best job of it (probably just trying to stay warm), or maybe it's just that the elements have had longer to decompose what little was left behind by the flames. In any case, in that section of the castle, Waterhouse finds a place where there's not too much rubble to shovel out, and where they can quickly enclose an adequate space with a combination of tarps and planks. It is diametrically opposed to the part of the castle that is still inhabited, which exposes it to winter storms but protects it from the prying eyes of the staff. Waterhouse paces off some rough measurements, then goes to his room, leaving Ghnxh to see to the decommissioning of the galvanick lucipher.
Waterhouse sketches out some plans for the upcoming work, at long last putting his hitherto misspent engineering skills to some use. He draws up a bill of required materials, naturally involving a good many numbers:
100 8' 2 x 4s is a typical entry. He writes out the list a second time, in words not numbers: ONE HUNDRED EIGHT FOOT TWO BY FOURS. This wording is potentially confusing, so he changes it to TWO BY FOUR BOARDS ONE HUNDRED COUNT LENGTH EIGHT FEET.
Next he pulls a sheet of what looks like ledger paper, divided vertically into groups of five columns. Into these columns he transcribes the message, ignoring spaces:
TWOBY FOURB OARDS ONEHU NDRED
COUNT LENGT HEIGH TFEET
and so on. Wherever he encounters a letter J he writes I in its stead, so that JOIST comes out as IOIST. He only uses every third line of the page.
Ever since he left Bletchley Park, he has been carrying several sheets of onionskin paper around in his breast pocket; when he sleeps, he puts them under his pillow. Now he takes them out and selects one page, which has a serial number typed across the top and is otherwise covered with neatly typed letters like this:
ATHOP COGNQ DLTUI CAPRH MULEP
and so on, all the way down to the bottom of the page.
These sheets were typed up by a Mrs. Tenney, an aged vicar's wife who works at Bletchley Park. Mrs. Tenney has a peculiar job which consists of the following: she takes two sheets of onionskin paper and puts a sheet of carbon paper between them and rolls them into a typewriter. She types a serial number at the top. Then she turns the crank on a device used in bingo parlors, consisting of a spherical cage containing twenty-five wooden balls, each with a letter printed on it (the letter J is not used). After spinning the cage the exact number of times specified in the procedure manual, she closes her eyes, reaches through a hatch in the cage, and removes a ball at random. She reads the letter off the ball and types it, then replaces the ball, closes the hatch, and repeats the process. From time to time, serious-looking men come into the room, exchange pleasantries with her, and take away the sheets that she has produced. These sheets end up in the possession of men like Waterhouse, and men in infinitely more desperate and dangerous circumstances, all over the world. They are called one-time pads.
He copies the letters from the one-time pad into the empty lines beneath his message:
TWOBY FOURB OARDS ONEHU NDRED ATHOP COGNQ DLTUI CAPRH MULEP
When he is finished, two out of every three lines are occupied.
Finally, he returns to the top of the page one last time and begins to consider the letters two at a time. The first letter in the message is T. The first letter from the one-time pad, directly below it in the same column, is A.
A is the first letter in the alphabet and so Waterhouse, who has been doing this cipher stuff for much too long, thinks of it as being synonymous with the number 1. In the same way, T is equivalent to 19 if you are working in a J-less alphabet. Add 1 to 19 and you get 20, which is the letter U. So, in the first column beneath T and A, Waterhouse writes a U.
The next vertical pair is W and T, or 22 and 19, which in normal arithmetic add up to 41, which has no letter equivalent; it's too large. But it has been many years since Waterhouse did normal arithmetic. He has retrained his mind to work in modular arithmetic-specifically, modulo 25, which means that you divide everything by 25 and consider only the remainder. 41 divided by 25 is 1 with a remainder of 16. Throw away the 1 and the 16 translates into the letter Q, which is what Waterhouse writes in the second column. In the third column, O and H give 14 + 8 = 22 which is W. In the fourth, B and O give 2 + 14 = 16 which is Q. And in the fifth, Y and P give 24 + 15 which is 39. 39 divided by 25 is 1 with a remainder of 14. Or, as Waterhouse would phrase it, 39 modulo 25 equals 14. The letter for 14 is O. So the first code group looks like
T W O B Y
A T H O P
U Q W Q O
By adding the random sequence ATHOP onto the meaningful sequence TWOBY, Waterhouse has produced undecipherable gibberish. When he has enciphered the entire message in this way, he takes out a new page and copies out only the ciphertext-UQWQO and so on.
The duke has a cast-iron telephone which he has put at Waterhouse's disposal. Waterhouse heaves it out of its cradle, rings the operator, places a call across the island to the naval station, and gets through to a radio man. He reads the ciphertext message to him letter by letter. The radio man copies it down and informs Waterhouse that it will be transmitted forthwith.
Very soon, Colonel Chattan, down in Bletchley Park, will receive a message that begins with UQWQO and goes on in that vein. Chattan possesses the other copy of Mrs. Tenney's one-time pad. He will write out the ciphertext first, using every third line. Beneath the ciphertext he will copy in the text from the one-time pad:
