Among other things, the lads had constructed a complete miniature railroad on the grounds, and had also built gliders of various types. But their most recent “craze” had been wireless telegraphy. With a dozen lads of their own age they had formed a “Wireless Club,” which met at High Towers every month. But, with the summer vacation, the members of the body had scattered, leaving only Jack and Tom to carry on the work. As Professor Chadwick stinted his son in nothing pertaining to his chosen pursuits, the two lads had assembled as complete an amateur station as could be found in the country. In addition to the latest instruments and appliances, their natural ingenuity had enabled them to invent several additional features, some of them patentable,—as, for instance, the call-bell which tapped out the mysterious summons to the island station. Which brings us back to Lone Island and to an explanation of how the two lads and Jupe, their faithful colored attendant, happened to be quartered on this low-lying, sandy, rather desolate patch of land off the coast of Texas, not far from the mouth of the Rio Grande. The islet belonged to Professor Chadwick, being part of an estate which had been owned by his wife, the daughter of a Texas cattle man. The lads had already camped there a winter, and knew the vicinity well. About two months before this story opens, Professor Chadwick had left home, bound, so he informed the lads, on a biological investigation cruise among the Florida Keys and the West Indies. The lads had heard nothing more of him, or of his steam yacht, the _Sea King_, with the exception of a letter from Key West, and another from the island of Jamaica, stating that all was going well. Imagine their bewildered astonishment and excitement therefore, when, two weeks before, a brief letter came to High Towers telling them to proceed, with Jupe, to Galveston, where the motor cruiser _Vagrant_ would be awaiting them. Their instructions continued to inform them that they were to equip the _Vagrant_ with wireless, and also purchase a portable bungalow and shed, with which to establish a wireless station on Lone Island. The letter, signed by Professor Chadwick, closed in his customary abrupt manner, without vouchsafing any explanation of his orders. But Jack and Tom hardly needed any. The letter opened up before them a delightful vista of fun and adventure. “Just fancy, a wireless island all to ourselves!” Jack had exclaimed as the boys joined hands in a wild war dance of delight. They had pleasant recollections of former jolly days in camp on the Gulf.