3. A direct proportion between rate of propagation and pressure within the external jugular vein could not be demonstrated.

4. Some of the waves, especially the presystolic and the systolic, travel faster than others.

LITERATURE:

(1) Gottwald, Pflüger's Archiv., Vol. 25, p. 1.

(2) Gerhardt, Archiv. f. exper. Pathologie, Vol. 34, p. 402.

(3) Friedreich, Deutsches Arch. f. klin. Med., Vol. 1, p. 241.

(4) Frédéricq, Travaux du lab. de Léon Frédéricq, Vol. 3, p, 85.

A FOREST FIRE AT ST. JOHN ABOUT 2000 YEARS AGO. By G. F. MATTHEW, LL.D., F.R.S.C.

The opening up of a bog deposit near St. John has revealed some interesting information about the physical history of the region around the Bay of Fundy in past ages, both antecedent to and contemporaneous with the presence of man on its shores. Not the least notable is the discovery that St. John was swept by a forest fire about the beginning of the Christian era.

Among the objects found in this peat bog are charred twigs, and flakes of wood also charred, that have been found at several points at a definite depth in the bog. These objects are scattered over the surface of a certain layer of the bog, where they are buried among unburned twigs, leaves of grass and other vegetable remains in a partly decayed condition, but so little changed that their brown color contrasts strongly with the jet black of the burned twigs.

From the way in which these light charred fragments are buried among the unburned material it is inferred that they were blown in upon the bog from the surrounding hills. These hills being much drier than the bog, would

be liable to be swept by forest fires, while the water-soaked bog would preserve the trees which were growing on it as well as the scorched fragments resting upon its surface. The antiseptic properties of the peat would help to preserve the charred fragments as well as the remains of the vegetation into which they had fallen, and thus bring them down to our time comparatively unchanged.

These burnt twigs are in a layer about two feet below the present surface of the bog. On this layer they are plentiful, but scattered examples are found about half an inch or an inch lower down. If we allow for the possibility of animals traversing the bog, we shall understand that it would be possible for some of the fragments of charcoal to be forced a short way into the yielding moss of its surface by their feet, and thus these fragments that are more deeply buried may have originally belonged to the one principal layer.

We have found this charcoal layer at the three points in the bog where sections of the bog deposit were taken, and always at about the same distance from the surface.

In 1880 and 1881 the author investigated the fresh water deposits of Lawlor's Lake, in the Torryburn valley, five miles N.E. of St. John; and incidentally in connection therewith, examined two dry basins in the same valley, one at the east and west ends of the lake. In the latter basin the section of the Recent deposit showed fragments of charcoal at a depth of two feet and a half. That this charcoal layer may have been cotemporary with that at the Rockwood bog seems probable, notwithstanding that it is buried to a greater depth, for through the Torry burn basin runs a small brook which, although connected originally with Lawlor's Lake by an underground passage through limestone rock, may be considered to have carried more sediment than could come to the Rockwood bog, which lies in the col of a small valley, from which the water flows in two directions; the Rockwood deposit at

this stage (two feet below the surface) was a purely vegetable deposit.

From the fact that both at Torry burn and Rockwood there is a charcoal deposit at about the same horizon in the Recent deposits, it appears reasonable to infer that they had probably a common origin, and that this was a forest fire, which extended over an area of at least some miles in the vicinity of St. John. The question arises-if there was such a fire at the time indicated, how was it set?

It has been suggested that such fires arise from the heat developed by a lightning stroke. But while buildings are often destroyed in this way, it would seem that growing trees, which are often struck, seldom take fire. This may be attributed to the dampness of the trunk and foliage, which rapidly conducts the electricity away; and then if a fire should originate from this cause, it stands a good chance of being extinguished by the rain which usually accompanies a thunder storm.

I have seen it stated that in the South of France forest fires have been known to originate from the drops of balsam which exude from pine trees, these drops forming natural lenses which concentrate the rays of the sun and lead to ignition of the wood through the resinous vapors that escape the balsam or gum.

It appears to the writer that neither of these causes has been active in this region in Recent Geological Time in setting fire to forests. For we have in the Rockwood bog a record of the physical events of this kind for a period reaching back for from 6000 to 9000 years. The Rockwood deposit has been carefully examined inch by inch, and layer by layer, from the summit to the bottom, and this in three different places, but no charcoal fragments have been met with, except at the one level of two feet below the surface. If the fire had been due to physical causes there is good reason to think that such fires would have recurred at intervals, from the time that the

country was first forest-clad, after the Champlain Period, until now, but, as we have remarked, only the one layer of scorched twigs and flakes of wood is known, and that at a period about two thousand years back.

Another possible source of such a fire is the agency of man. It is claimed by some archaeologists that the earliest men on this continent were unacquainted with the use of fire. To men of this race we will not ascribe the calamity which devastated the neighborhood of St. John; but men who knew not of fire were followed by those who did know, and the carelessness of such a people seems sufficient cause for the phenomenon in the Rockwood bog. We know the care which the savage exercises to prevent the spread of fire from his camping ground; he knows the destruction of game animals that would accompany the sweep of a forest conflagration, which for the sake of himself and his tribe is to be avoided. The savage also is in constant fear of his human enemies, and the smoke of his camp-fire might reveal his presence to a prowling adver sary; hence he makes his camp-fire as small as possible, and hovers over it. The fire he makes is thus also easily extinguished. The first users of fire, however, who entered the Acadian forests may not have learned or felt the need of these precautions, and thus have carelessly allowed a fire to spread. From these various considerations we infer the probability that the forest fire recorded in the Rockwood bog was due to the agency of man.

Is it possible to fix within a reasonable limit the time when this event occurred?

Only those who have sectioned and examined the trees and shrubs which grow on the margin of what the Danes call a Skovmose or Forest Bog can have any conception of the exceedingly slow rate at which trees grow in such situations. In the first place, their roots are constantly buried in the cool, damp moss, and the whole plant is constantly bathed in the moist and chilled air that covers the

bog. But further, it is impossible for the roots of such trees to reach a magazine of mineral sustenance, such as the ground affords, but as a recompense they spread out their long slender roots to a surprising distance over the surface of the bog in search of food. The juices of the bog afford them little or no lime and potash, the roots can not pass through the water-soaked subsoil, and so they are literally starved. Spruce trees (Abies nigra) that are no better than little shrubs in such situations, will show by the rings of growth that they are 30 or 40 years old. A growth for the same number of years would have enabled their brethren on the upland to reach the size of stalwart

trees.

Cedar trees (Thuja occidentalis) also have been dwarfed in the same way, but not to the same extent, as some of them have finally struggled up to considerable dimensions. One such tree, the tenacity of whose roots had been weakened by the drainage of the bog, due to the operations of the park commissioners of Rockwood Park, had fallen across the canal they made. The overturning of the tree showed just how far the roots descended into the bog, and it was to a depth no greater than six inches; the boll of the tree had sunk deeper than this, owing to the weight of its trunk, but the lowest layer of roots started out at this level to radiate through the moss of the bog. At the time the tree fell the lower tier of roots had perished (probably many years before), and the life of the tree was sustained by an upper tier of roots that spread out about three inches from the surface of the bog. Many of the roots of even this second tier had perished, for the tree had long passed its prime.

One of the park commissioners was kind enough to have the tree sawed as near to the base as the heart wood remained, and thus exposed the annual layers of growth. On counting these layers it was found that the tree had attained the age of four hundred years. Moss grew up