“All right, Dad,” Jack had agreed. “But, remember, the selection of the radio equipment is to be left to the fellows and me. We’ve had a lot of experience with the value of radio when in a tight place, especially in South America, and we want to put that experience to use and be prepared for every contingency this time.”
To this Mr. Hampton readily had agreed, with the result that in Seattle the three boys had revelled in the radio equipment stores, which they found well stocked, as the use of radio had developed greatly on the Pacific.
In consequence, their outfit included radio field equipment of the most powerful, yet most compact, designs. For while Mr. Hampton fully realized the value of having the very best yet he had issued a solemn warning that bulk must be considered.
“We will have to travel as lightly as consistent with safety and the purpose of our expedition,” he had said. “So don’t pile up anything too heavy or bulky, or it will have to be discarded.”
Jack knew well that the distance which can be covered with a radiophone transmitter is only about one-fourth as great as that of a wireless telegraph transmitter having the same input of initial current. Therefore, as a means of sending messages, supposedly for aid, over long distances, the wireless telegraph would be the better, inasmuch as equipment for it would be less bulky to transport than equipment for transmitting the human voice. Nevertheless, he was reluctant to place their sole dependence upon the wireless telegraph.
“You see, Dad,” he had pointed out to his father, when the outfit was being assembled, “to reach the outside we shall have to depend upon wireless telegraph. But we will also need the radiophone for this reason: that each one of us ought to have a means of calling the main party in case we become separated through going on scouting or hunting expeditions, or for any reason.”
“Well, that sounds sensible,” his father had agreed. “Go ahead with your plans, but, remember, hold down the bulk.”
The result was that equipment capable of telegraphing five hundred miles was assembled, but also Jack made up five light field sets of radio, one for each of their party and for Farnum, which the user could pack in his clothing and which had a radius up to twenty-five miles. The instrument was Jack’s now famous ring radio, worn on the finger, with a setting only one inch by five-eighths of an inch. Formerly an umbrella as aerial had been employed but Jack had done entirely away with that in his improved set.