«But how—»

«Surely—»

«It can't—»

«Gentlemen!» came the voice of the Chaplain. «Let Lord Asriel explain.»

«It's Dust,» Lord Asriel repeated. «It registered as light on the plate because particles of Dust affect this emulsion as photons affect silver nitrate emulsion. It was partly to test it that my expedition went north in the first place. As you see, the figure of the man is perfectly visible. Now I'd like you to look at the shape to his left.»

He indicated the blurred shape of the smaller figure.

«I thought that was the man's daemon,» said the Enquirer.

«No. His daemon was at the time coiled around his neck in the form of a snake. That shape you can dimly see is a child.»

«A severed child—?» said someone, and the way he stopped showed that he knew this was something that shouldn't have been voiced.

There was an intense silence.

Then Lord Asriel said calmly, «An entire child. Which, given the nature of Dust, is precisely the point, is it not?»

No one spoke for several seconds. Then came the voice of the Chaplain.

«Ah,» he said, like a thirsty man who, having just drunk deeply, puts down the glass to let out the breath he has held while drinking. «And the streams of Dust…»

«—Come from the sky, and bathe him in what looks like light. You may examine this picture as closely as you wish: I'll leave it behind when I go. I'm showing it to you now to demonstrate the effect of this new emulsion. Now I'd like to show you another picture.»

He changed the slide. The next picture was also taken at night, but this time without moonlight. It showed a small group of tents in the foreground, dimly outlined against the low horizon, and beside them an untidy heap of wooden boxes and a sledge. But the main interest of the picture lay in the sky. Streams and veils of light hung like curtains, looped and festooned on invisible hooks hundreds of miles high or blowing out sideways in the stream of some unimaginable wind.

«What is that?» said the voice of the Sub-Rector.

«It's a picture of the Aurora.»

«It's a very fine photogram,» said the Palmerian Professor. «One of the best I've seen.»

«Forgive my ignorance,» said the shaky voice of the old Precentor, «but if I ever knew what the Aurora was, I have forgotten. Is it what they call the Northern Lights?»

«Yes. It has many names. It's composed of storms of charged particles and solar rays of intense and extraordinary strength—invisible in themselves, but causing this luminous radiation when they interact with the atmosphere. If there'd been time, I would have had this slide tinted to show you the colors; pale green and rose, for the most part, with a tinge of crimson along the lower edge of that curtain-like formation. This is taken with ordinary emulsion. Now I'd like you to look at a picture taken with the special emulsion.»

He took out the slide. Lyra heard the Master say quietly, «If he forces a vote, we could try to invoke the residence clause. He hasn't been resident in the College for thirty weeks out of the last fifty-two.»

«He's already got the Chaplain on his side…» the Librarian murmured in reply.

Lord Asriel put a new slide in the lantern frame. It showed the same scene. As with the previous pair of pictures, many of the features visible by ordinary light were much dimmer in this one, and so were the curtains of radiance in the sky.

But in the middle of the Aurora, high above the bleak landscape, Lyra could see something solid. She pressed her face to the crack to see more clearly, and she could see the Scholars near the screen leaning forward too. As she gazed, her wonder grew, because there in the sky was the unmistakable outline of a city: towers, domes, walls…Buildings and streets, suspended in the air! She nearly gasped with wonder. The Cassington Scholar said, «That looks like…a city.» «Exactly so,» said Lord Asriel.

«A city in another world, no doubt?» said the Dean, with contempt in his voice.

Lord Asriel ignored him. There was a stir of excitement among some of the Scholars, as if, having written treatises on the existence of the unicorn without ever having seen one, they'd been presented with a living example newly captured. «Is this the Barnard-Stokes business?» said the Palmerian Professor. «It is, isn't it?»

«That's what I want to find out,» said Lord Asriel. He stood to one side of the illuminated screen. Lyra could see his dark eyes searching among the Scholars as they peered up at the slide of the Aurora, and the green glow of his daemon's eyes beside him. All the venerable heads were craning forward, their spectacles glinting; only the Master and the Librarian leaned back in their chairs, with their heads close together.

The Chaplain was saying, «You said you were searching for news of the Grumman expedition, Lord Asriel.

Was Dr. Grumman investigating this phenomenon too?»

«I believe he was, and I believe he had a good deal of information about it. But he won't be able to tell us what it was, because he's dead.»

«No!» said the Chaplain.

«I'm afraid so, and I have the proof here.»

A ripple of excited apprehension ran round the Retiring Room as, under Lord Asriel's direction, two or three of the younger Scholars carried the wooden box to the front of the room. Lord Asriel took out the last slide but left the lantern on, and in the dramatic glare of the circle of light he bent to lever open the box. Lyra heard the screech of nails coming out of damp wood. The Master stood up to look, blocking Lyra's view. Her uncle spoke again:

«If you remember, Grumman's expedition vanished eighteen months ago. The German Academy sent him up there to go as far north as the magnetic pole and make various celestial observations. It was in the course of that journey that he observed the curious phenomenon we've already seen. Shortly after that, he vanished. It's been assumed that he had an accident and that his body's been lying in a crevasse all this time. In fact, there was no accident.»

«What have you got there?» said the Dean. «Is that a vacuum container?»

Lord Asriel didn't answer at first. Lyra heard the snap of metal clips and a hiss as air rushed into a vessel, and then there was a silence. But the silence didn't last long. After a moment or two Lyra heard a confused babble break out: cries of horror, loud protests, voices raised in anger and fear.

«But what—»

«—hardly human—»

«—it's been—»

«—what's happened to it?»

The Master's voice cut through them all.

«Lord Asriel, what in God's name have you got there?»

«This is the head of Stanislaus Grumman,» said Lord Asriel's voice.

Over the jumble of voices Lyra heard someone stumble to the door and out, making incoherent sounds of distress. She wished she could see what they were seeing.

Lord Asriel said, «I found his body preserved in the ice off Svalbard. The head was treated in this way by his killers. You'll notice the characteristic scalping pattern. I think you might be familiar with it, Sub-Rector.»

The old man's voice was steady as he said, «I have seen the Tartars do this. It's a technique you find among the aboriginals of Siberia and the Tungusk. From there, of course, it spread into the lands of the Skraelings, though I understand that it is now banned in New Denmark. May I examine it more closely, Lord Asriel?»

After a short silence he spoke again.

«My eyes are not very clear, and the ice is dirty, but it seems to me that there is a hole in the top of the skull. Am I right?»

«You are.»

«Trepanning?»

«Exactly.»

That caused a murmur of excitement. The Master moved out of the way and Lyra could see again. The old Sub-Rector, in the circle of light thrown by the lantern, was holding a heavy block of ice up close to his eyes, and Lyra could see the object inside it: a bloody lump barely recognizable as a human head. Pantalaimon fluttered around Lyra, his distress affecting her.