stretched, between two lofty poles, the antennæ of the wireless station. Against these the electric waves from out of space were beating and sounding the wireless “alarm-clock,” an invention of Ding-dong’s of which he was not a little proud.

Ding-dong had become inoculated with the wireless fever as a result of the trip east which the Motor Rangers had taken following their stirring adventures in the Bolivian Andes in Professor Grigg’s air-ship—which experiences were related in the fourth volume of this series, The Motor Rangers’ Cloud Cruiser. On their return to California—where all three boys lived, in the coast resort of Santa Barbara—nothing would suit Ding-dong but that they take a vacation on Goat Island and set up a wireless plant for experimental purposes.

“I want to try it and away from home where a bunch of fellows won’t be hanging about and joking me if I make a fizzle,” he explained.

As the lads while in the east had done a lot of business, some of it connected with Nat’s gold mine in Lower California and some with interests of Professor Griggs, they decided that they were entitled to at least a short period of inactivity, and Ding-dong’s idea was hailed as a good one. Goat Island, a rugged, isolated spot of land shaped like a splash of gravy on a plate, was selected as an ideal camping place. The wireless appliances, shipped from San Francisco, were conveyed to the island on board the Rangers’ sturdy cabin cruiser Nomad, and three busy, happy weeks had been devoted to putting it in working order. Since the day that it had been declared “O. K.” by Ding-dong, the lads had been crazy for the “wireless alarm” to ring in, and when it failed to do so Ding-dong came in for a lot of good-natured joshing.

For some further account of the three chums, we must refer our readers to the first volume of this series, The Motor Rangers’ Lost Mine. This related how Nat, the son of a poor widow, unexpectedly came into his own and from an employé’s position was raised to one of comparative affluence. For a holiday tour when they returned from Lower California, where Nat by accident had located his mine, the chums took an eventful trip through the Sierras. What befell them there, and how they combated unscrupulous enemies and had lots of jolly fun, was all set forth in the second volume devoted to their doings, The Motor Rangers Through the Sierras. Some sapphires found by them on this trip led to a strange series of incidents and adventures attendant on their efforts to restore them to their rightful owner. The precious stones were stolen, recovered, and lost again, only to be delivered safely at last. These exciting times, passed by the lads on their cruiser, the Nomad, which took them half across the Pacific, were described in the third volume of the young rangers’ doings, The Motor Rangers on Blue Water. Their voyage in Professor Grigg’s wonderful air-ship, the Discoverer, has been already referred to. With this necessarily brief introduction to the young campers, let us return to Goat Island.

Directly Ding-dong reached the hut housing the apparatus, he flung himself down before the instruments and hastily jammed the head-piece, with its double “watch-case” receivers, over his ears. He picked up a pencil and placing it conveniently above a pad of paper that was always kept affixed to the table holding the sending and receiving appliances, he began to send a storm of dots and dashes winging out in reply to the wireless impulse that had set the gong sounding.

“This is Goat Island!” he banged out on the key, while the spark leaped and writhed in a “serpent” of steel-blue flame between the sparking points. It