"And that's the time we'll be ready with the masks," declared Nort.

Bud Merkel was as excited as either of his cousins when he heard the news. He declared no better plan could be devised than going against the unknown cave dwellers with gas masks and a telephone message was soon on the way, asking the commander of the Los Pompan branch of the American Legion for the loan of as many of the protectors as were needed.

In due time word came back that the Dot and Dash ranchers were quite welcome to the masks. Snake and Kid, as experts in their use, and as judges of the best ones to bring back, were sent as a committee into town to get the life-saving apparatus.

It was next day, when the gas masks had been tried on by the cowboys who were to use them, and plans were being talked over for a second attack, that Nort suggested:

"Maybe we ought to try these masks before we use them. They may be defective in spite of the fact that they look all right."

"Not a bad idea," agreed Bud. "But we haven't any poison gas to try 'em with."

"If we could go in a room filled with ammonia, or some such vapor as that, we could soon tell if the masks were any good," Dick suggested.

Dr. Taylor was communicated with and agreed to supply from his somewhat limited laboratory sufficient fumes to make a sure test of the masks. He came out to the ranch, a small room was set aside for the experiment and into this vile chamber the men went one at a time, each one wearing the mask that was designed to protect him in the coming fight.

With the exception of one or two of the affairs, each one was gas proof and the defective ones were quickly replaced with good ones. So that in a comparatively short time the avengers were once more ready to make the attack.

Much the same tactics were observed as on the former occasion. The horses were left well out of reach of any clouds of vapor that might float from the ravine, and the guards were instructed to deploy their reserve cavalry to east or west, according to the direction of the wind, in case gas was noted coming out of the defile.