The days passed swiftly. Ernest was less homesick after Schmidt's arrival and the intelligent German's industry and interest in the work completely won Roger's heart. When the week of his visit was up, Roger resolved that he would find a way to feed three instead of two if he had to start the camp to eating desert mice. He wrote now to the Dean, asking him to sell his laboratory equipment. Dick took the letter to town.

The absorber was not as ambitious a structure as the engine house. Nevertheless, it took twice as long to build as Roger had thought it would. The foundations consisted of a shallow trough raised from the ground on four by four supports. It covered several hundred square feet and sloped very gently to carry the flow of oil. It was covered with double layers of window sash. The task of laying this was considerable and in spite of the men's best efforts, the breakage was large enough to use up practically all the reserve glass. But the most trying task of all was that of making the great trough leak proof with asphaltum. Even after the rest of the job was done and the huge cold frame lay gleaming mightily in the desert sun, the men still puttered with leaks in the trough, which they tested by pouring water over in lieu of the oil which would ultimately form the flow.

Roger and Ernest were at work on this task one morning when Gustav returned with a barrel of water from the ranch. Before driving back with the team he came excitedly round the corner of the engine house.

"The alfalfa vas up already!" he shouted. "A little shadow of green on yellow sand. Lieber Gott! vat a country! And the kleine Felicia almost eating it like a little rabbit. And Dick talks like it vas golt. And he vas vorried. He says a sand storm vas coming to-day. Look!"

Gustav pointed down the valley to the south. A gray blue haze, not unlike a sea fog, was slowly advancing.

"Fasten up the tents. I go back mit the horses," said Gustav, disappearing as abruptly as he had arrived.

"If any one thinks a little thing like a sand storm can stop work on the plant, he's mistaken," grunted Roger. "Anyhow Dick said one wasn't due for six weeks."

Ernest looked from the approaching gray cloud to Roger's obstinate mouth, shrugged his shoulders and daubed another brush full of hot asphaltum over a crack.

Suddenly a hot blast of air took their hats off. The tent gave a boom. The window-sash resting against the engine house wall fell with a tinkling crack. Without a word the two men ran to close the tent. When they had finished, the whole world was a swirling dust cloud through which they could not perceive each other when ten feet apart.

"Make for the engine house!" roared Ernest. "I'll fetch the old lady."