is a question of great difficulty; and the conjecture made is, that it is an inflow of the cold water from the vast area of the antarctic."
The geographical work of the United States has been more limited than usual, owing to delay and smallness of appropriations. The Coast Survey continues its work: in the Gulf of Mexico careful soundings have been made, and observations on the temperature of the water and the flow of currents, which will throw light on the Gulf Stream. Triangulations were pushed eastward from the Pacific Coast Range to the Sierra Nevada, some of the triangles observed having sides over 150 miles long; a series of telegraphic determinations of longitude have been made for the purpose of correcting our charts of the West India Islands, one point at least having been located on each island. Triangulation along Lakes Ontario, Erie, and Michigan, has been continued, the topography of Niagara River completed, many points determined for the State survey of Michigan, and the elevation of the Great Lakes newly determined. Lake Ontario is found to be 247.25 feet and Lake Erie 573.58 feet above mean tide at New York. Reports of geographical and topographical work in Montana, the Yellowstone Park, Southern Colorado, Northern New Mexico, and Arizona, have been issued. The geographical surveys west of the 100th meridian, under Lieutenant Wheeler, have been continued. About 25,000 square miles were traversed by the various parties. Some interesting Spanish mines were found in New Mexico. A survey was carried on in the neighborhood of Lake Tahoe, in California. The depth of the lake was found to exceed 2,200 feet. The examination of the Colorado River, with reference to determining the practicability of diverting it from its channel to irrigate the deserts of Southeastern California, has been completed. The lowest part of the desert is 200 feet below the sea, and it was found that an area of 1,600 square miles could be flooded; but constantly-shifting sands would make it a continual expense, and the evaporation from the surface of such a lake would exceed the water flowing in the Colorado in a dry season. Thirteen atlas sheets of Lieutenant Wheeler's survey have been issued; they are upon a scale of eight miles to the inch, and cover a large part of Nevada, Utah, Arizona, New Mexico, and Colorado. The survey of the Territories under Profs. Hayden and Powell was carried on, and much has been learned of the region embracing Colorado, Utah, and Southeastern Nevada. A triangulation party climbed and measured Blanco Peak, near Fort Garland, in Colorado, which, if not the highest, is next to the highest peak in the Rocky Mountains. It is 14,464 feet high. Over fifty of the most elevated peaks in that range are in the State of Colorado, running from 14,000 to 14,500 feet, so close that the utmost care has been required to determine which is the highest.
Eastern Utah was surveyed from the Colorado River to and over the Wahsatch Mountains between parallels 38° and 39° 15'. The region
