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The relations between transparency, color, and temperature of the water are discussed by O. d'Aufsess in Ann. d. Physik.; the color affects the temperature, the temperature does not affect the color. It is not necessary to make comparative transparency observation always under the same conditions of the sky; the author found with his white disk, 1 meter in diameter, the same transparency value at noon with a cloudless sky, and after sunset. To study the influence of organic compounds which turn the color into yellow, he filtered water through vegetable earth, and determined the amount of soluble organic matter in the lake water. For the meteorological service in German East Africa H. Maurer has devised a sun-dial which has proved useful at twenty stations whose magnetic declination is unknown and whose latitude is only known within half a degree. The instrument is disk-shaped. The dial forms a semi-cylindrical surface, the axis of the cylinder, the style, lying in the plane of the framing. When the style is mounted parallel to the earth's axis, a plummet rests against the quadrant plane and marks the latitude on it. There is a notch in the style, producing on the dial a spot of light, whose position is, by turning the instrument, adjusted to the sun's declination for the day according to a table. At the International Hydrogr'ftphical conference recently held at Copenhagen, the Scottish delegate, Mr. Robertson, of Dundee, described some recent and interesting new discoveries he had. made concerning the Gulf Stream. It has heretofore been popularly believed that the section of the Gulf Stream which reaches the Faroe Islands goes direct to Norway. Mr. Robertson has discovered from the result of his investigations that the section, however, travels first to the Shetland Islands and then to Norway. He also pointed out that the Southern Gulf Stream sends a section to the North Sea which runs along the coast of Scotland and the North of England, touches Jutland, and then travels north. The high degree of saltness and the temperature in the North Sea this hydrographer has found to be purely attributable to this source.
