that of sight, but of vastly greater penetration, power and scope and not dependent upon light; a sense only vaguely forecast by ancient work upon clairvoyance.

By the use of his new mental equipment he succeeded in entering a Boskonian base upon Boyssia II. There he took over the mind of the communications officer and waited. A pirate ship working out of that base captured a hospital ship of the Patrol and brought it in. Clarrissa, now chief nurse of the captured vessel, working under Kinnison's instructions, stirred up trouble. Helmuth, from Grand Base, interfered, thus enabling the Lensman to get his second, all-important line.

The intersection of the two lines, Boskonia's Grand Base, lay in a star cluster well outside the Galaxy. Pausing only long enough to destroy the Wheelmen of Aldebaran I, the project in which his first attempt had failed so dismally, he investigated Helmuth's headquarters. He found fortifications impregnable to any massed attack of the Patrol, manned by beings wearing thought-screens. His sense of perception was suddenly cut off—the enemy had thrown a thought-screen around the whole planet.

He returned to Prime Base, deciding en route that boring from within was the only possible way in which that base could be reduced. In consultation with Haynes the zero hour was set, at which the Grand Fleet of the Patrol would start raying Helmuth's base with every available projector.

Pursuant to his plan, Kinnison again visited Trenco, where Tregonsee and his Rigellians extracted for him fifty kilograms of thionite, the noxious drug which, in microgram inhalations, makes the addict experience all the physical and mental sensations of doing whatever it is that he wishes most ardently to do. The larger the dose the more intense the sensations—but the slightest overdose means a sudden and super-ecstatic death.

Thence to Helmuth's planet; where, by controlling the muscles of a dog whose brain was unscreened, he let himself into the central dome. Here, just before zero time, he released his thionite into the primary air stream, thus wiping out all the pirate personnel except Helmuth; who, in his inner dome, could not be affected. The Patrol attacked on schedule. Kinnison killed Helmuth in hand-to-hand combat. Grand Base was blasted out of existence, largely by the explosion of bombs of duodecaplyl atomate placed by the pirates themselves. These bombs were detonated by an enigmatic, sparkling force-ball which Kinnison had studied with care. He knew that it was operated by thought, and he suspected—correctly—that it was in reality an 

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