On the lakes of Switzerland and of other countries, there used to exist certain habitations of man. These are the so-called _lacustrine dwellings_ which we shall have hereafter to consider in some considerable detail, when we come to the Bronze Age. The men who lived on these lakes were necessarily fishers; and some traces of their fishing-nets have been discovered by a circumstance which chemistry finds no difficulty in explaining. Some of these lake-dwellings were destroyed by fire; as, for instance, the lacustrine settlements of Robenhausen and Wangen in Switzerland. The outsides of these cabins, which were almost entirely constructed of wood, burnt, of course, very readily; but the objects inside, chiefly consisting of nets--the sole wealth of these tribes--could not burn freely for want of oxygen, but were only charred with the heat. They became covered with a slight coating of some empyreumatic or tarry matter--an excellent medium for insuring the preservation of any organic substance. These nets having been scorched by the fire, fell into the water with the _débris_ of the hut, and, in consequence of their precipitate fall, never having come in actual contact with the flame, have been preserved almost intact at the bottom of the lakes. When, after a long lapse of centuries, they have been again recovered, these _débris_ have been the means of affording information as to the manufacture both of the fishing-nets, and also as to the basket-work, vegetable provisions, &c., of these remote ages. In one of Dr. Keller's papers on these _lacustrine dwellings_, of which we shall have more to say further on, we find a description and delineation of certain fishing-nets which were recovered from the lake of Robenhausen. In the Museum of Saint-Germain we inspected with curiosity several specimens of these very nets, and we here give a representation of one of them. There were nets with wide meshes like that shown in fig. 78, and also some more closely netted. The mesh is a square one, and appears to have been made on a frame by knotting the string at each point of intersection. All these nets are made of flax, for hemp had not yet been cultivated. [Illustration: Fig. 78.--Fishing-net with wide Meshes.] These nets were held suspended in the water by means of floats, made, not of cork, but of the thick bark of the pine-tree, and were held down to the bottom of the water by stone weights. We give a representation here (fig. 79), of one of these stone weights taken from a specimen exhibited in the Museum of Saint-Germain. [Illustration: Fig. 79.--Stone Weight used for sinking the Fishing-nets.]