"Over in the Ramapo Mountains, not far from Tuxedo. I'll have you there in two hours. Sure you can spare the time to go out there now?" Vanderventer was enthusiastically eager. "Spare the time? You just try and keep me from going!" Neither of them noticed the sinister figure that lurked outside the door which led into the adjoining office. They chattered excitedly as they passed into the outer hall and made for the elevator. * * * * * Vanderventer's laboratory was a small domed structure set in a clearing atop the mountain and well hidden from the winding road which was the only means of approach. Though Bart Madison, who had inherited his father's prosperous brokerage business, had financed his friend's research work ever since the two left college, this was his first visit to the secluded workshop, and its wealth of equipment was revealed to him as a complete surprise. He had always thought of Van's experiments as something beyond his ken; something uncanny and mysterious. Now he was convinced. The most prominent single piece of apparatus in the laboratory was a twelve-inch reflecting telescope which reared its latticed framework to a slit in the dome overhead. Paralleling its axis and secured to the same equatorial mounting was a shining tube of copper which bristled with handwheels and levers and was connected by heavy insulated cables to an amazing array of electrical machinery that occupied an entire side of the single room. "Regular young observatory you've got here, Van," Bart commented when he had taken all this in in one sweeping glance of appraisal. "Yeah, and then some. Not another like it in the world." Van was busying himself with the controls of his electrical equipment, and a powerful motor-generator started up with a click and a whirr as he closed a starting switch. Madison watched in silence as the swift-fingered scientist fussed with the complicated adjustments of the apparatus and then turned to the massive concrete pedestal on which his telescope was mounted. At his touch of a button the instrument swung over on its polar axis to a new position. The slit in the dome was opened to the afternoon sky, revealing the lunar disc in its daytime faintness. "You can see it just as well in daylight?" Bart asked as his friend peered through the eyepiece of the telescope and continued his adjustments. "Sure, the surface is just as bright as at night. Doesn't seem so to your eye, but it's different through the telescope. Here, take a look." * * * * * Bart squinted through the eyepiece and saw a huge crater with a shadowed spire in its center. Like a shell hole in soft earth it appeared--a great splash that had congealed immediately it was made. The cross-hairs of the eyepiece were centered on a small circular shadow near its inner rim.