On the previous evening an all-night vigil had been kept, and messages had been read, but I only here record my own experiences of this exciting spy-hunt. On reaching our point of vantage I learned that suspicion had first been aroused by a mysterious and intense white light being shown from a window in the country mansion in question, which was situated upon so strategic a point that it could be seen very many miles in the direction of London. And there, sure enough, was the one brilliant light--at all other windows of the house the blinds being drawn--shining like a beacon all over the country. It had shone first at 6.30 p.m. that night, and, as I watched, it showed till 6.48, when it disappeared. After three minutes it was shown till 7.30 exactly, when suddenly it signalled in Morse the code-letters "S.M." repeated twice, and then disappeared till 9 o'clock, when again the same signal was made. The light remained full on for ten minutes, and was then suddenly switched off. This was certainly remarkable. The officers with me--all experts in signalling--were unanimous as to the two letters, and also to their repetition. These signals, I learned, had been seen times without number, but until the smart young officer who had called upon me had noticed them, no action had been taken. Having established that mysterious signalling was really in progress, I set forth upon further investigation. Taking my own signalling-apparatus, a very strong electric lamp with accumulators and powerful reflectors, which would show for fifteen miles or more, I got into the car with my companions--who were eager to assist--and, having consulted ordnance-maps and compass, we went to a spot high-up in an exposed position, where I anticipated the answering light from the mansion might be seen. We found ourselves in a private park, upon a spot which, by day, commands an immense stretch of country, and from which it is said that upon a clear day the Sussex coast can be seen. Here we erected our signalling-apparatus and waited in patience. The night proved bitterly cold, and as the hours crept slowly by, the sleet began to cut our faces. Yet all our eyes were fixed upon that mysterious house which had previously signalled. For hours we waited in vain until, of a sudden, quite unexpectedly from the direction of London, we saw another intense white light shining from out the darkness. For a full half-hour it remained there, a beacon like the other. Then suddenly it began winking, and this was the code-message it sent: "S.H.I.S. (pause) H. 5. (pause) S.H.I.S.F. (pause with the light full on for two minutes). I.S. I.E. (pause) E.S.T. (light out)." Turning my signal-lamp in its direction, I repeated the first portion of the mysterious message, and then, pretending not to understand, asked for a repetition. At once this was given, and, with my companions, I received it perfectly clearly!