."

"Gee, but you're a regular pessimist, Rog!" exclaimed Dick.

"No, I'm not. No inventor is. I'm just open minded. And don't think I'm
blue, either. If I weren't so heckled and worried by the time and money
element I'd be having the time of my life. Wouldn't I, Felicia, honey?"

There was no answer. Felicia, with the oil can hugged tight against her
middy, was curled up on the work bench, fast asleep.

"Well, it seems to me I'd better take my family home," said Dick.
"Where's the rest of my harem? Elsa! Charley! Come with papa."

By eleven o'clock the camp was quiet. Roger prowled about the condenser
a bit, covered the engine with canvas and then went to bed. It had been
a hard day and none of the three men were wakened by the smell of
sulphur dioxide that began to hang over the camp at midnight. The dawn
wind blew most of it away, but when Gustav rose to get breakfast, he
sniffed suspiciously and called Roger. They traced a leak in the lower
tier. Half the charge had evaporated during the night.

"At least two weeks before we get more and a chunk out of the precious
grub money," groaned Ernest at breakfast.

"Patience! Patience!" exclaimed Gustav. "I'll start to Archer's Spring
mit the empty drums to-morrow."

Roger, who had been bolting his breakfast in silence, suddenly set down
his coffee cup. Patience! He had told Charley that he was a patient man.
Yet every muscle of his body at the moment was twitching with
impatience. He acknowledged this to himself, then said aloud:

"No use getting nervous, boys, I'm not. You get the new charge, Gustav.
I'll leave that in your hands and think no more about it. I'm going over
my heat tables again."

"I'll help you check over," said Ernest.

"If you don't mind I'd rather grind for a few days on it alone. I can
think better that way. Then I'll go over the results with you."

"All right," returned Ernest, with his usual good nature. "Gustav and
I'll offer our services to Dick to-day on his new field. Do increase
your absorbing area, Roger!"

Roger shook his head. "That's an awkward and expensive solution. The
answer's in the engine!"

He began to figure on an old envelope. When this was covered, he
continued his calculations on the margin of an old newspaper spread over
the work house table. Long after Gustav and Ernest had gone about their
day's business Elsa found him here, sweating in the stifling glare from
the sun and sand, hair disheveled, shirt open at the