"I'll try a narrower spread and less curve."
Grantline was searching the magnified images on the series of amplifier grids. There was nothing. For an hour we worked; then suddenly Grantline cried: "Gregg! Wait! Hold it!"
I tensed, stricken. I held the angle and the spread of light steady.
"Two seconds of arc, east; try that. The damned thing is shifting." He gripped me. "It's at the eastern edge of the field; it shifts off. It must be in rapid motion."
Then I saw it, a mere moving dot of black; but suddenly it clarified. I saw a dot which I could imagine was a shape with discs along its edge, moving with high velocity. Grantline was shifting our field to hold it.
"Got it, Gregg. By God, that's it! Now we'll see."
Then presently we saw that from its bow a very faint radiant beam was streaming. Beside me I heard Grantline gasp, "Gregg, am I crazy or is that bow beacon like the light-beam planted in Greater New York?"
There did seem to be a similarity, but thought of it abruptly was swept from my mind. Our cubby was alive with signals. Both the bow and the stern observers saw the enemy ship now with their 'scopes gazing directly along our Benson-light. And Drac was calling, "I've got the measurement of its velocity. Doubling every ten seconds. God, what acceleration!"
I flung off the Benson-light. The enemy ship had come from behind the limb of the Moon; our straight-light telescopes showed it clearly. It was heading unmistakably in our direction.
Drac was pleading, "We need velocity! Are you coming to the turret?"