"We will first make a test of the temperature," said Mr. Roumann, "as that will be the easiest." Accordingly a thermometer was put outside, and those in the air-craft anxiously watched the red column of spirits. The temperature was marked as seventy-five inside the Annihilator, but the thermometer had not been outside more than a second before it began falling.
"Good!" exclaimed Mr. Henderson, as he noted it. "The temperature is going down. I'd rather have it too cold than too hot. We can stand a minus fifty of cold better than two hundred and twelve of heat. We have fur garments with us."
"It is still going down," remarked Jack, as he saw the red column drop down past the thirty mark.
"Below freezing," added Mark.
The spirits fell in the tube until they touched twenty-eight degrees, and there they remained.
"Twenty-eight degrees," remarked Professor Henderson. "That isn't so bad. At least, we can stand that if we are warmly clad."
"Yes, but it will be colder to-night," said Jack. For they had landed on the moon in bright sunlight.
"To-night?" questioned the German scientist, with a smile.
"Yes, it's always colder when the sun goes down," went on the lad.
"You have forgotten one thing," said Mr. Henderson, with a smile at his young protégé. "You must remember, Jack, that the nights and days here are each fourteen days long—that is, fourteen of our days."