3. _Level of Lake._--Amongst the problems of a discursive character here referred to, perhaps there is none of greater interest than that which deals with the cause and effect of the change that has taken place in the level of the lake. From eye-witnesses we know that, before the first drainage was carried out, the mound used to be covered with water in the winter-time; and Mr. Charles Reid tells me that the line of level which he has adopted in measuring for the plan of the lake is 8 feet 7 inches above the log pavement. Now the area assigned to the lake by Mr. Reid is considerably less than what the old residenters of the district make it out to have been, as several of them have stated that they had seen its waters extend beyond the road on the west side (see Plan), and yet from his data the depth of water would just cover the highest part of the mound, which, it will be remembered, was about the same height above the log pavement. Originally the island must have been higher than the lake, but allowing that the log pavement was only 3 feet above the surface of the water, we have at least 11 feet of change of level to account for. This phenomenon could only be caused by a sinking of the whole island, or a rising of the water, or a combination of both causes. I do not think that the weight of the island and its superincumbent mass would press so heavily on the bottom of the lake as to cause it to sink much, since the enormous amount of wood-work, of which it consisted, being lighter than water, would have a corresponding buoyant effect, and so help to counteract the weight of the aërial portion. Nor has any great compression of its substance taken place from decay, because in the course of making the deep section under the log pavement, we found the contour of the large trees quite symmetrical and perfectly round; and although the wood was very soft it was not compressed, owing to its being completely saturated with water, which of course is virtually incompressible. Although I have often seen small brushwood flattened from pressure, yet I have never seen this effect produced on a branch larger than my wrist, and only in one instance did I notice it on a piece of wood of this size. Moreover, the gangway, which certainly could not sink from its weight, was deeply buried, its uppermost horizontal beams being not less than 7 feet below the surface of the field. We must therefore fall back on the only other alternatives, and assign this change in the relative position of the crannog and level of the lake either to a general compression and sinking of the bed of the lake or to the rising of the water. The latter result is somewhat unusual, because running water, having a tendency to deepen its channel, and the accumulation of sedimentary deposits, often produce an opposite effect, and cause the complete drainage of lake basins. I have therefore carefully examined the outlet of the lake to ascertain if possible the causes that led to