In two long army huts, situated a short distance from each other, the wireless office had been established. One of them housed the generator and transmitting gear, while in the other was the operating key and reception set. To the latter hut Geoffrey went, and there, with the assistance of a Belgian wireless operator, he unpacked the double-note magnifier and condensers which had travelled by air from Croydon.
Then throughout the remainder of the afternoon the keen young engineer was engaged in setting them up upon the operating bench. With many patient tests he listened-in constantly for various stations of between nine hundred and sixteen hundred mètres. The small oblong box, on the ebonite top of which were fixed two little vacuum tubes which shone brightly when current was passed through them—the piece of apparatus used in conjunction with the seven-valve amplifier—magnified the weakest signal to such an extent that the telephones could hardly be borne upon his ears.
He had another there, but it somehow did not give such good results as the one he had just requisitioned from Chelmsford. As a matter of fact, it was one of a rather newer design, for wireless apparatus is every week improving. And so rapid is the advance of radio discoveries that much of the latest experimental apparatus to-day will six months hence be relegated to the scrap-heap.
Through the whole afternoon he worked on patiently, joining up the receiving circuit of many wires, the transmission side being already in running order. Only three days before he had spoken over the radio-telephone to Croydon, Lympe, Pulham in Norfolk, Le Bourget, and Cologne. Each test gave excellent results, even though the atmospheric conditions were none too good.
So he had every hope of the official tests being satisfactory. As a loyal and trusted servant of that wonderful organisation, the Marconi Company, he had worked hard and done his level utmost to make the Bouvignes station a credit to his employers. Hence he was most anxious that on the great day when the final tests were made everything should go right, and that signals by continuous-wave telegraphy, direction-finding, and radio-telephony should be equally satisfactory.
He was listening to Paris transmitting to Bucharest, reading the commercial messages, and gazing through the small window of the Army hut away across the grass-covered aerodrome to where, below, the winding Meuse lay bathed in the soft evening light. Still listening, he raised his wave-length until he heard the peculiar arc note of N.S.S.—which is Annapolis in the United States—sending its time signals, for it wanted a minute to five o’clock. Having compared the time with the big round clock above the bench he reduced his wave-length to one thousand mètres, when suddenly he heard the shrill high-pitched note of a continuous-wave transmitter which sounded as though it were in the near vicinity.
It was calling S.R.4. repeatedly, without giving its own call-sign. But as the wireless station being called did not appear in the official register at his elbow, he took it to be some private station and disregarded it.
At that moment Captain Hanateau, who was in charge of the new aerodrome, entered the hut, saying in good English:
“Here is a telegram for you, Meester Falconer.”
Geoffrey thanked him, tore open the message, but as he read it, he held his breath in anxiety and astonishment. His heart stood still.