BUILDING THE PROJECTILE
"Did you see that?" exclaimed Jack.
"What?" asked Professor Henderson quickly.
"Some one at the window," replied Jack.
"I saw the face," added Mark. "It was a man looking in."
"A man? What sort of a man?" inquired Mr. Roumann, and he showed some excitement.
"I couldn't tell very well," answered Jack. "I saw him for only a second. But the man was looking right in."
"Did he have a heavy black mustache?" asked the German, and strode rapidly toward the window.
"No, he didn't have a mustache at all," said Jack. "He was smooth–shaven. I'm sure of that."
"Then it can't be he," murmured Mr. Roumann.