Curiously enough, next day a foreigner--probably a German--arrived at the hotel, and, as may be imagined, I at once took steps to keep him under the strictest observation. He was a quiet, apparently inoffensive person about thirty-five, who, among his impedimenta, brought a motor-cycle and box camera. Before he had been in the place twenty-four hours I had convinced myself that he was the spy Straus. This fact I wired to Bruton Street in the code we had long ago arranged, hoping that the message would find my friend. To my surprise, all the reply I got was: "Be careful that you have made no mistake." What could he mean? I read and re-read the message, but remained much puzzled, while my excitement increased. Each day the new arrival, who had written the name of "F. Goldstein" in the visitors' book, went forth on his cycle to explore the beauties of the Highlands, the thaw having now cleared the roads, and on each occasion I managed by dint of many subterfuges to watch his proceedings. His gaze was ever in the distance, and each time he gained high ground he swept the surrounding country with a pair of powerful prismatic field-glasses. I confess I was rather annoyed at Ray's conduct in thus abandoning me at the very moment of my discovery, for here was the ballooning expert Straus bent upon seeing and photographing our newest arm of defence. As the days passed I exerted every precaution, yet I followed him everywhere, sometimes using the car, and at others the motor-cycle. The spy, a bespectacled, round-faced Teuton who spoke with a strong accent, was ever active, ever eager to discover something in the air. Yet, to my intense satisfaction, he seemed to be utterly unaware that I was keeping so strict a watch upon his movements. Purposely I avoided speaking to him in the hotel, for fear of arousing his suspicions. One day Mr. Goldstein did not appear, and in response to my inquiry the waiter informed me that he had caught cold and was confined to his room. A spy with a cold! I laughed within myself, and the afternoon being bright, I took a run south through the Abernethy Forest down to Loch Pityoulish. On my return I crossed Dulnan Bridge, where the turbulent Dulnan River hurtles along over the stones on its way down to the Spey. I dismounted, hot and tired, and propped up my cycle against the parapet to rest and admire the dark pine-clad gorge which opened to the north. My reflections were suddenly cut short by a loud humming sound which seemed to come from the road which I had just traversed. Instinctively I looked round for the approaching motor-car. The sound came nearer, but instead of a car, I saw in the air, above the tops of the firs against the distant hill in the background, a splendid aeroplane with two men aboard. Swiftly it swept over the stream with the ease and majesty of an enormous albatross!