This discovery was the spark which lighted up a torch destined to dissipate the darkness which hung over a long-protracted and little-known period of man's history. Previous to the discovery made on the dried-up bed of the Lake of Zurich, various instruments and singular utensils had been obtained from the mud of some of the lakes of Switzerland, and piles had often been noticed standing up in the depth of the water; but no one had been able to investigate these vestiges of another age, or had had any idea of ascribing to them anything like the remote antiquity which has since been recognised as belonging to them. To Dr. Keller the honour is due of having interpreted these facts in their real bearing, at a time when every one else looked upon them as nothing but objects of curiosity. It is, therefore, only just to pronounce the physician of Zurich to have been the first originator of pre-historic archæological science in Switzerland. In 1854, after the publication of Dr. Keller's first article, the Swiss lakes were explored with much energy, and it was not long before numerous traces of human settlements were discovered. At the present day more than 200 are known, and every year fresh ones are being found.[32] Thanks to the activity which has been shown by a great number of observers, magnificent collections have been formed of these archæological treasures. The fishermen of the lakes have been acquainted, for many years back, with the sites of some of these settlements, in consequence of having, on many occasions, torn their nets on the piles sticking up in the mud. Numerous questions were asked them, and they were taken as guides to the different spots, and ere long a whole system of civilisation, heretofore unknown, emerged from the beds of the Swiss lakes. Among the lakes which have furnished the largest quantity of relics of pre-historic ages, we may mention that of Neuchâtel, in which, in 1867, no less than forty-six settlements were counted; in Lake Constance (thirty-two settlements); in the Lake of Geneva (twenty-four settlements); in the Lake of Bienne, canton of Berne (twenty settlements); in the Lake of Morat, canton of Fribourg (eight settlements). Next come several other lakes of less importance. The Lake of Zurich (three settlements); the Lake of Pfæffikon, canton of Zurich (four settlements); the Lake of Sempach, canton of Lucerne (four settlements); the Lake of Moosseedorf, canton of Berne (two settlements); the Lake of Inkwyl, near Soleure (one settlement); the Lake of Nussbaumen, canton of Thurgau (one settlement); the Lake of Zug, &c. Pile-work has also been discovered in former lakes now transformed into peat-bogs. We must place in this class the peat-bog of Wauwyl, canton of Lucerne (five settlements).