"Addison," he said hoarsely--"don't joke about it!--don't joke. It was
not a grey vapour that strangled Seager...."
"Certainly it was not. Seager was strangled by some wholly inoffensive
person--we shall probably never know his identity--who had fallen asleep
amongst the bushes on the mound, close beside the house...."
"But man alive! I've _seen_ the beastly thing, with my own eyes! You've
seen it! Wales saw it! Mrs. Ord saw it!..."
"Mrs. Ord saw her husband."
"Ah! you're coming round to my belief about the Ords!"
"Decidedly I am."
"But what did Wales see--eh? And what did _I_ see!"
"You saw the vapour in operation."
The Major fell back in his chair with an expression upon his face which
I cannot hope to describe. Words failed him altogether.
"I had come prepared for something of the sort," I continued rapidly;
"for I have investigated several cases of haunting--notably in the Peak
district--which have proved to be due to an emanation from the soil--a
vapour. But the effect of such vapour, in the other cases, was to
induce delusions of sight, in nearly every instance (although, in two,
the delusions were of hearing).
"In other words, the person affected by this vapour was drugged, and,
during the drugged state, perceived certain visions. I made the mistake,
at first, of supposing that Low Fennel came within the same category.
The classical analogy, of course, is that of the Sibyls, who delivered
the oracular responses from the tripod, under the afflatus of a vapour
said to arise from the sacred subterranean stream called Kassotis. The
theory is, therefore, by no means a new one!"
Major Dale stared dully, but made no attempt to interrupt me.
"There are probably many spots, in England alone," I continued,
"thus affected; but, fortunately, few of them have been chosen as
building-sites. Barrows and tumuli of the stone and bronze age, and
also Roman shrines, seem frequently to be productive of such emanations.
The barrow beside Low Fennel (and now under the new wing) is a case in
point.
"Sudden atmospheric changes seem to be favourable to the formation
of the vapour. The barrow in Peel Castle, Isle of Man, is peculiarly
susceptible to thunder-storms, for instance, whilst that at Low Fennel
emits a vapour only after a spell of intense heat, and at the exact
moment when the temperature begins to fall again. In the case of a
sustained heat-wave, this would take place at some time during each
night.
"And now for the particular in which the vapour at Low Fennel differs
from other, similar emanations. It is not productive of delusions of
sight; it induces a definite and unvarying form of transient insanity!"
Major Dale moved slightly, but still did not speak.
"Dame Pryce was the first recorded victim of the vapour. She was accused
of witchcraft by a neighbour who testified to having seen her transform
herself into a hideous and unrecognizable hag--whereas, in her proper
person, she seems to have been a comely old lady. Lack of evidence
compels us to dismiss the case of Seager, but consider that of the Ords.
The man Ord, on his own confession, had fallen asleep outside the house.
He became a victim of the vapour--and his own wife failed to recognize
him.
"To what extent the mania so produced is homicidal remains to be proved;
the gas is rare and difficult to procure, so that hitherto analysis has
not been attempted. My own theory is that the subject remains harmless
provided that, whilst under the mysterious influence, he does not
encounter any person distasteful to him. Thus, Seager may have met his
death at the hands of some tramp who had been turned away from the
house.
"As to the symptoms: they seem to be quite unvarying. The subject
strips, contorts his face out of all semblance to humanity (and always
in a particular fashion) and crawls, lizard-like upon the ground, with
the head held low, in an attitude of listening. That it is possible so
to contort the face as to render it unrecognizable is seen in some cases
of angina pectoris, of course.
"The subject apparently returns to the spot from whence he started and
sinks into profound sleep, as is seen in some cases of somnambulism;
and--like the somnambulist, again--he acquires incredible agility. How
you yourself came, twice, under the influence of the vapour, is easily
explained. The first time--when the housekeeper saw you--you had
actually been in bed; and the second time, as you have told me, you had
gone upstairs, undressed, and then slipped on your dressing-gown in
order to complete some work in the study. Instead of completing the
work, you dozed in your chair--and we know what followed! In the case
of--Mrs. Dale...."
"God! Addison," said the Major huskily, and stood up, clutching the
chair-arms--"Addison! You are trying to tell me that--what I saw was ...
_Marjorie_!..."