"Aye, it was Baldur who discovered that plan, and was slain by Loki for exposing it," Odin said somberly. "Loki had perfected a remote control for that sliding door, operating by tuned vibration. Here it is."
And Odin showed me, among the many dust-covered instruments in the chamber, a small, square silver box. On it was mounted a knob whose pointer could be turned along a semi-circular scale.
"Turning this knob would open the sea-door a bit or wide," the Aesir king said. "When Loki fled from Asgard, he took this control box with him. And when we trapped him in that cave below Midgard, and we were about to kill him, Loki threatened to open the sea-gate wide and destroy us all. That was why we had to agree not to kill him, if he would surrender this control box to us. He did surrender it. We kept our word and did not kill him, but placed him in the suspended animation in which he lay for so long."
Odin went to the door and called up through the corridors for some of his thralls to come. When they came, he bade them carry out the big spherical copper generator.
"We shall place it on Vigrid field, on the mainland across Bifrost Bridge," he said, "and keep it under guard tonight. For it is there that we must make our stand against Loki's forces when they come in all their fury."
He, Thor and I followed the thralls as they bore the heavy mechanism through Valhalla castle and out into the windy, gusty night. Torch-bearing thralls went ahead to illuminate the way. Lights shone from all the castles of Asgard. The Moon was hidden by driving clouds as we moved in a little torchlit group across the giddy span of Bifrost to the flat field on the opposite promontory,
My plane was still where I had landed it. Aesir warriors and mounted scouts were on guard, watching toward the south for the first approach Of Loki and the Jotun horde. As Odin directed the placing of the copper mechanism, I went to my plane. Something had occurred to me which might enable me to devise an additional weapon for the coming battle.
In the plane were the half-dozen big signal rockets which were to be used in case I made a forced landing and had to summon help. I began taking the rockets apart, pouring out the gun powder in them, and carefully unfixing the detonators. At the end of a half-hour, I had made three crude hand-grenades or small bombs. I hoped they might be of some use against the Jotuns, who knew nothing of explosives. I left the bombs in the plane and emerged to find Thor waiting for me.
"My father has already returned to Asgard," the Hammerer told me. "And it is time we followed him, for our nightly Valhalla feast begins soon."
"Thor, what of tomorrow's battle?" I asked. "If it comes to sword and spear, with the Jotuns outnumbering us many times, what can we do?"