There was one strange fact that Sarakoff had told me the night before, and that I had verified. The bacillus was ultra-microscopical—that is, it could not be seen, even with the highest power, under the microscope. Its presence was only to be detected by the blue stain it gave off during its growth.
CHAPTER V
THE GREAT AQUEDUCT
The Birmingham reservoirs are a chain of lakes artificially produced by damming up the River Elan, a tributary of the Wye. The great aqueduct which carries the water from the Elan, eighty miles across country, travelling through hills and bridging valleys, runs past Ludlow and Cleobury Mortimer, through the Wyre Forest to Kidderminster, and on to Birmingham itself through Frankley, where there is a large storage reservoir from which the water is distributed.
The scenery was bleak and desolate. Before us the sun was sinking in a flood of crimson light. We walked briskly, the long legs of the Russian carrying him swiftly over the uneven ground while I trotted beside him. Before the last rays of the sun had died away we saw the black outline of the Caban Loch dam before us, and caught the sheen of water beyond. On the north lay the river Elan and on the south the steep side of a mountain towered up against the luminous sky. The road runs along the left bank of the river bounded by a series of bold and abrupt crags that rise to a height of some eight hundred feet above the level of the water. Just below the Caban Dam is a house occupied by an inspector in charge of the gauge apparatus that is used to measure the outflow of water from the huge natural reservoirs. The lights from his house twinkled through the growing darkness as we drew near, and we skirted it by a short detour and pressed on.
"How long does water take to get from here to Birmingham?" asked Sarakoff as we climbed up to the edge of the first lake.
"It travels about a couple of miles an hour," I replied. "So that means about a day and a half."
We spoke in low voices, for we were afraid of detection. The presence of two visitors at that hour might well have attracted attention.
"A day and a half! Then the bacillus has a long journey to take." He stopped at the margin of the water and stared across the shadowy lake. "Yes, it has a long journey to take, for it will go round the whole world."