In 1885 Rotch was able to obtain basic data on the heights and movements of various clouds by means of triangulation measurements. In 1894, Rotch became the first in the world to sound the atmosphere by lifting instruments on kites. Ultimately kites sounded the atmosphere to an altitude of 5 kilometers and provided Rotch with information concerning fundamental upper air patterns of wind, temperature, and humidity, as well as their relationship to surface weather patterns. In 1904, at the St. Louis World's Fair, Rotch initiated the use of sounding balloons in the U.S. These balloons carried recording instruments beyond even the highest clouds to a height of 17 kilometers. Rotch and Leon Teisserenc de Bort, discoverer of the stratosphere, made extensive upper-air kite measurements from ships in the tropical and sub-tropical North Atlantic. These permitted publication in 1911 of a chart of aerial routes, thus pointing the way to the feasibility of transatlantic air travel aided by air patterns. Rotch became the first director of the observatory and maintained it at his own expense until his death in 1912, when he bequeathed it to Harvard University with an endowment of $50,000.