f the vacuum-chamber are
pressure-tempered colloid (no glass would endure the strain for an
instant) and a junior engineer with tinted spectacles watches the Ray
intently. It is the very heart of the machine--a mystery to this day.
Even Fleury who begat it and, unlike Magniac, died a multi-millionaire,
could not explain how the restless little imp shuddering in the U-tube
can, in the fractional fraction of a second, strike the furious blast
of gas into a chill greyish-green liquid that drains (you can hear it
trickle) from the far end of the vacuum through the eduction-pipes and
the mains back to the bilges. Here it returns to its gaseous, one had
almost written sagacious, state and climbs to work afresh. Bilge-tank,
upper tank, dorsal-tank, expansion-chamber, vacuum, main-return (as a
liquid), and bilge-tank once more is the ordained cycle. Fleury's
Ray sees to that; and the engineer with the tinted spectacles sees to
Fleury's Ray. If a speck of oil, if even the natural grease of the human
finger touch the hooded terminals, Fleury's Ray will wink and disappear
and must be laboriously built up again. This means half a day's work for
all hands and an expense of, one hundred and seventy-odd pounds to the
G.P.O. for radium-salts and such trifles.

"Now look at our thrust-collars. You won't find much German compo there.
Full-jewelled, you see," says Captain Hodgson as the engineer shunts
open the top of a cap. Our shaft-bearings are C.M.C. (Commercial
Minerals Company) stones, ground with as much care as the lens of a
telescope. They cost L837 apiece. So far we have not arrived at their
term of life. These bearings came from "No. 97," which took them over
from the old Dominion of Light which had them out of the wreck of the
Persew aeroplane in the years when men still flew wooden kites over oil
engines!

They are a shining reproof to all low-grade German "ruby" enamels,
so-called "boort" facings, and the dangerous and unsatisfactory alumina
compounds which please dividend-hunting owners and turn skippers crazy.
The rudder-gear and the gas lift-shunt, seated side by side under the
engine-room dials, are the only machines in visible motion. The former
sighs from time to time as the oil plunger rises and falls half an inch.
The latter, cased and guarded like the U-tube aft, exhibits another
Fleury Ray, but inverted and more green than violet. Its function is
to shunt the lift out of the gas, and this it will do without watchi