All day Monday, Roger and his two helpers sweated to prepare for the plant's first trial. Roger would let no one touch the engine but himself, but Ernest and Gustav puttered with the condenser and the pump and at dawn started the oil circulating through the absorber. All day long the burning desert sun poured its heat through the glass into the oil which caught and imprisoned it for Roger's purpose, until the storage pit was full. Roger had set the time of trial as nine o'clock in the evening in order to prove the night as well as the day power of his plant. The Prebles appeared shortly before the hour.
"Everything O. K.?" asked Dick, with a creditable effort at being off-hand.
"One never knows till afterward," replied Roger. "Come into the engine house. No room for you, Peter, old man."
There were three "bugs" lighted over the engine. Ernest and Gustav were both smoking violently. Dick was chewing gum. Elsa and Charley said nothing but watched every movement on the part of the men.
"Come here, Felicia," said Roger, biting at his cold pipe. "You see this little valve? All right. Now, as I've told you many times, I hope that when you turn this, that the sun which shone to-day will turn the big fly wheel round. When I give the wheel a twist, you turn the valve clear over."
"Yes, Roger," replied Felicia, her little fingers quivering as she grasped the valve.
"Now!" exclaimed Roger, tugging at the fly-wheel.
There was a moment's breathless silence. Then very slowly and sedately, the fly wheel began to revolve, gathered speed and shortly was chugging away steadily. A little cheer rose from Roger's audience. He grinned.
"Now Ern, let's throw in the pump." A belt, connecting the engine with the pump outside, was quickly slipped in place. The engine slowed down. But a moment later the sound of water pouring over the condenser pipes was heard above the chugging of the engine and pump.
Gustav and Ernest fell on each other's necks. "It works!" squealed Felicia. "It works and I helped make it, I did." Peter, his head as far in at one of the windows as a very short neck would carry it, brayed. Roger watched the pressure gauge and scratched his head thoughtfully.
Charley and Felicia slipped outside to inspect the pump, and Charley called: "Does anybody smell anything?" At the same moment Felicia shrieked.
"Oh! oh, Roger! There's a terrible leak out here!"
Roger shut off the engine and followed by the others, he darted to the condenser. The odor of sulphur dioxide filled the night.