The interior of the building was free from dust of any sort and the light filtered down from the roof in the same manner in which the embalming gallery had been illuminated. The library initially was a disappointing experience from my point of view though to my companions the evening was one of the most exciting since we had entered this fantastic underground world. If I had expected papyrus, manuscript or great sheets of vellum, I was sadly disappointed. The place, after we had ascended an interminable series of ramps, appeared to be a series of gigantic chambers, each bearing different inscriptions along the walls.
There were hundreds of great stone benches in each chamber, ranged before a large stone edifice like a lectern; set in front of the lectern parapet was a curious metallic surface, rather like a formal representation of an eye, with incised symbols in its raised contours. It appeared to be hollow and when Scarsdale's lantern flickered into its interior the pale light disclosed what looked like a primitive mechanism of metal. Facing the lectern but hundreds of metres away was a vast pale curved stone surface which projected from the wall. To my mind it resembled nothing more than a pre-historic version of a modern lecture hall in one of our universities but Scarsdale solved the enigma in an accidental and somewhat bizarre fashion.
He disappeared from our sight for a few moments round the plinth of the lectern-structure and the next moment we were blinded as light poured into the building; I am afraid that I cowered down behind one of the stone benches in rather an undignified manner while my companions were almost as much affected. In brilliantly delineated fashion and about a hundred feet high, vast symbols in the strange language burned at us on the far wall of the library. Then the room became dim again and Scarsdale's chuckle of satisfaction changed into a laugh of triumph.
'There is your library, gentlemen,' he beamed. 'This place is nothing more than a modern cinema-theatre. The information was stored something in the manner of a slide and projected on to the stone screen. What price the Lumiere Brothers now?'
There was a moment's stupefied silence and then the air was filled with amazed questions.
Van Damm went round behind the lectern with the professor, who explained that he had accidentally projected the rays of his helmet lantern down into the strange machine.
'My light source was far too strong, of course,' he explained. 'These people would have had something far subtler and less powerful, as befits the general lighting level in the ancient city of Croth. But this was undoubtedly the basis of it. There was a slide, so to speak, left in the machine. What we now have to find is the source of their power and the place where they stored their slides and we shall begin to disentangle something of the enigma of the city.'
Fourteen
The remainder of that day was spent in a fevered chaos by Scarsdale and Van Damm in particular. Though the discovery of the picture-machine in the ancient city beneath the ground was of stupefying importance from an archaeological and historical point of view it did not excite me as much as might have been supposed. Naively, I had imagined that we were to see something like early newsreel films of this long-forgotten civilisation. Instead, the reality, when it came was much more prosaic though the Professor and his scientific companions passed an evening much like that of Lord Carnarvon and Howard Carter when they discovered the tomb of Tutankhamen.
In point of fact what the Great Northern Expedition had unearthed was equally as important, possibly more so, as the city of Croth had never even been suspected until Scarsdale and one or two obscure scholars had begun their researches into certain forbidden books. What Scarsdale and Van Damm had reanimated in what they came to call the Central Library of the city was, in fact, a visual method of projecting book pages so that hundreds of people could take part in readings at one time. This would not only have served the same function as our modern cinema for this ancient people but obviously took the place of printing for them, as by this method they had only to 'publish' one particular book for the entire population.
When Van Damm himself discovered the central deposits, the raison d'etre for the whole building, there was a high pitch of excitement so that I felt constrained to go back across the square to relieve Prescott, so that he could join in an occasion of outstanding interest. What the doctor and Scarsdale were so enthused about was, I had to admit to myself, something pretty spectacular in the way of breaking new ground and the Great Northern Expedition would go down in history for this alone.
What had happened was that Van Damm had accidentally dislodged a bronze knob somewhere behind the lectern; the others had felt a draught shortly after and had then noticed that a dark slot had appeared' in the rear wall of the building. The lever apparently operated an ingenious series of counterbalances, sliding back a stone door cut from one slab of material but so thinly and accurately that my colleagues found it could be pushed to and fro with one hand.
What they found within, ranged upon minutely indexed stone shelves and in elaborately inscribed storage bins, were thousands of exquisitely engraved metal cylinders. How these had been created, it was not clear, as there were no tools discernible, but no doubt, Scarsdale surmised, we would find metalworkers' shops and those of other skilled artisans within the city itself.
The cylinders contained many different 'frames' of material, each evidently representing a numbered page of a book or communication. The figures and symbols were punched with such delicacy and precision — letters like O having the central portion linked to the main symbol with exquisitely fine tracery work — that they could be projected complete to give a representation of the page upon the stone screen in the auditorium below.
When the cylinders were placed on a central pin on the machine, which presumably had some sort of light source within its hollowed-out interior, it could then be revolved to bring various faces of the work projected to the viewer's notice in proper numbered sequence. Van Damm himself had expected there to be a series of lenses, as in a modern movie projector, but this proved not to be the case.
The light, whose source remained a mystery, passed through a sort of pinhole as in that old form of camera, and by a racking device which animated the spindle, could be focused by natural light intensity, funnelling it through the metal ring on the exterior of the pulpit. We then realised that the design of the mechanism, which could only 'focus' within very narrow limits, made necessary for the whole building to be constructed to suit the apparatus. In other words, the length of the projector's 'throw' determined the point at which the rear wall screen would be built. The effect can be realised by noting the projection of a sign on a glass door when sunlight repeats the pattern on a light wall some distance away.
There was no denying the tremendous nature of this discovery, and Scarsdale and those who followed would be able to learn much of this ancient civilisation from the deciphering of the cylinders. But further examination would have to wait as we had the whole city before us, wide open for exploration. I took the first watch as sentry that night and noted that the sleep of my companions was markedly broken by the excitement of this extraordinary day.