In 1826, he accompanied Van Sturlen, the director, on the quadrennial journey to Yedo, taking with him a young native physician, a native artist, and several servants to assist his researches into natural history. Following, as Fisscher had done, nearly or quite in Kämpfer’s old route, he saw, in the passage across Kiūshiū, the same old camphor-tree, as flourishing, apparently, as it had been a hundred and thirty-five years before, but with a hollow in its trunk large enough to hold fifteen men. He visited the same hot springs, and descended some sixty feet into the coal mine, near Kokura, mentioned by Kämpfer. He saw only one thin seam of coal, but was told of thicker ones below,—an account which the coal drawn up seemed to confirm. [Illustration: THE WEDDING CEREMONY] At Yedo he met with many Japanese physicians, astronomers, and others, of whose acquisitions he speaks with much respect. Besides the other means, already pointed out, of measuring time, he saw in use there Chinese clepsydras, or water-clocks; but the method most relied upon for scientific purposes was a clock of which the idea was derived from one introduced into China by the Jesuit Ricci, and brought thence to Japan. This clock is worked by two balances, one to act by day and the other by night. The arm of each balance is notched, to accord with the variations in the length of the hours. At the summer solstice the weights are hung respectively upon the outermost notch of the day-balance, and upon the innermost notch of the night-balance. At intervals of six days, four hours and twelve minutes, both weights are moved; that of the day-balance a notch inward, that of the night-balance a notch outward, until at the winter solstice their original positions are reversed.