y and versatility they were far ahead of Earth's best modern efforts.
Grouped together in the center of the cavern were many assemblies of apparatus linked together by small cables that descended from main cables in the girder-crisscrossed ceiling overhead. There was a soft hissing of sparks leaping between terminals and a steady glow from oddly shaped tubes which indicated that the mechanisms were still functioning in silent and efficient performance of their unknown tasks.
* * * * *
The piece of apparatus nearest the door was an upright skeleton framework of slender pillars housing in their center a cluster of coils set around a large drumlike diaphragm. Foster wondered if this were not the signal device with which Layroh had tuned in his own portable instrument. The principal piece of mechanism in the central space, however--a great crystal-walled case filled with an intricate array of rods and wires--was something at whose purpose Foster could not even guess.
Layroh strode on p