"No time, now, Eliot!" the Hawk rapped out, turning at the door. "Just do as I say--and hurry! I'll get them!" And he was gone. CHAPTER X _The Promise Fulfilled_ Although puzzled by the Hawk's promise, Leithgow could only put his trust in it and go ahead with the preparations as he had been directed. He took two of his three laboratory assistants off their hurried manufacture of quantities of the V-27, and with Ku Sui went out into the air-car. Passing by way of tube and lake and air, they were quickly inside the dome on the asteroid, and then into Ku Sui's laboratory, where Friday waited on guard. Completely docile and friendly, the Eurasian indicated the various instruments and devices he would need for the operations, and these were transported quickly. Then came the case of coordinated brains. Dr. Ku detached in connections with expert fingers, and all but Leithgow took a corner and carried it with infinite care to the air-car outside. "Do I stay here, suh?" Friday asked the Master Scientist in a whisper. Though informed of the change in Dr. Ku effected by the V-27, he was still very suspicious of him. "Seems to me he's a bit too meek and mild, suh. I think I ought to go down and watch him." Eliot Leithgow did not quite know what answer to give. The Eurasian forced the decision. "I will need," he observed, in his new, frank voice, "all the assistance you can possibly give me. I am faced by a tremendous task, and the use of every man will be necessary. I would suggest, Master Leithgow that the Negro be brought down." And so Friday came and the asteroid was left unguarded. A mistake, this turned out to be, but under the circumstances Eliot Leithgow could hardly be blamed for it. There was so much on their minds, so much work of vital importance, so desperate a need for speed, that quite naturally other considerations were subordinated. The asteroid, to the naked eye, was invisible; it could attract no attention; its occupants had all been disposed of. Certainly it seemed safe enough to leave it unguarded for a while. However, Eliot Leithgow took one precaution. Down in his own laboratory again, in the midst of the work of transferring Dr. Ku's operating equipment from the air-car, he called aside one of his assistants and instructed him to go and survey the asteroid through the infra-red device every ten minutes: and with this order the old scientist dismissed the matter from his mind, and turned all his energies to preparing the laboratory for the operations. * * * * *