"'I hardly follow you,' said Musgrave. 'The paper seems to me to be of no practical importance.' "'But to me it seems immensely practical, and I fancy that Brunton took the same view. He had probably seen it before that night on which you caught him.' "'It is very possible. We took no pains to hide it.' "'He simply wished, I should imagine, to refresh his memory upon that last occasion. He had, as I understand, some sort of map or chart which he was comparing with the manuscript, and which he thrust into his pocket when you appeared?' "'That is true. But what could he have to do with this old family custom of ours, and what does this rigmarole mean?' "'I don't think that we should have much difficulty in determining that,' said I. 'With your permission we will take the first train down to Sussex and go a little more deeply into the matter upon the spot.' "The same afternoon saw us both at Hurlstone. Possibly you have seen pictures and read descriptions of the famous old building, so I will confine my account of it to saying that it is built in the shape of an <b>L</b>, the long arm being the more modern portion, and the shorter the ancient nucleus from which the other has developed. Over the low, heavy-lintelled door, in the centre of this old part, is chiselled the date 1607, but experts are agreed that the beams and stone-work are really much older than this. The enormously thick walls and tiny windows of this part had in the last century driven the family into building the new wing, and the old one was used now as a storehouse and a cellar when it was used at all. A splendid park, with fine old timber, surrounded the house, and the lake, to which my client had referred, lay close to the avenue, about two hundred yards from the building. [Illustration: "IT HAS A GIRTH OF TWENTY-THREE FEET."] "I was already firmly convinced, Watson, that there were not three separate mysteries here, but one only, and that if I could read the Musgrave Ritual aright, I should hold in my hand the clue which would lead me to the truth concerning both the butler Brunton and the maid Howells. To that, then, I turned all my energies. Why should this servant be so anxious to master this old formula? Evidently because he saw something in it which had escaped all those generations of country squires, and from which he expected some personal advantage. What was it, then, and how had it affected his fate?