Part I Four Centuries Of Surprises


From 1851 to 1854 Henry employed Lorin Blodget to aid in compiling and analyzing the data received in Washington. But Henry had misgivings about his subordinate’s scientific competence and was disturbed when Blodget began to publish maps made from the Smithsonian data under his own name. Dismissed in 1854, Blodget used his newfound leisure to write his book Climatology . It won immediate acclaim and a wide readership because its numerous maps displayed the climatic patterns of the nation in a clear and comprehensible form. “Isothermal” maps—essentially contour maps of average temperatures—showed graphically just how little correlation existed between lines of latitude and climate.

Many of the isothermal maps in Climatology were technically faulty, and many were drawn from insufficient data, but they had a wide influence. Their implication, for example, that lands on the Canadian prairie might be warmer and more hospitable than people had thought made Blodget, one historian has argued, “one of the actual openers of the Northwest to settlement.” Politicians in the 185Os debating the extension of slavery in the United States drew on the newly fashionable vocabulary of climatology to argue whether “isothermal laws” would prevent the northward spread of plantation agriculture, thought to be suitable only for. warm regions.

During the years just preceding the Civil War, the meteorologist William Ferrel outlined principles governing the global pattern of winds and climates that are still accepted today. With the coming of the war, in 1861, however, the organized collection of data in the South largely ceased. The importance of the weather to military operations did bring forth such individuals as Francis L. Capen, a self-styled “certified practical meteorologist and expert in computing the changes in the weather.” In 1863 he wrote Abraham Lincoln that “thousands of lives and millions of dollars may be saved by the application of science to War.” Lincoln later summed up their encounter in a memorandum: “He told me three days ago that it could not rain again till the 30th of April or 1st of May. It is raining now [April 28] & has been for ten hours. I can not spare any more time to Mr. Capen.”

The postwar years finally saw the establishment of a national weather service with observing and forecasting missions. The catalyst was the weather itself, in the form of a series of destructive storms that swept the Great Lakes region and the Northeast coast in November 1869. A resolution for a weather service passed Congress in February 1870 and received President Grant’s approval. The task of organization went to the U.S. Army Signal Service because of its experience in communications, so vital to the quick relay of weather information. A number of people protested putting a scientific enterprise under military control, but the Signal Service moved quickly, opening offices in the major shipping cities on the Atlantic, Gulf, and Pacific coasts, as well as along the shores of the Great Lakes.

Forecasts for one or two days in advance were issued at Washington under the direction of Professor Cleveland Abbe, former head of the Cincinnati Observatory, who became known affectionately as “Old Probabilities,” or “Old Probs” for short. The opponents of military control kept a sharply critical eye on the new weather service, and eventually even the director of the service, the Arctic explorer and hero Maj. Gen. Adolphus Washington Greely, advocated converting it into a civilian agency. In 1891 the United States Weather Bureau, operating under the Department of Agriculture, took over all the weatherrelated functions of the Signal Service. With the establishment of a large network of cooperative citizens during the 189Os, practically every county in the United States had a volunteer who made standard observations of local temperature and precipitation data so that truly national climate maps could be constructed.

Meteorology in our century has built on the achievements of the past to gain an unprecedented grasp of the workings of the atmosphere. Its heroes have been less the colorful innovators of earlier days than the new technologies that have broadened and elevated the weather observer’s horizon.

The limitation of meteorological measurements to a two-dimensional plane seriously restricted any study of storm movement and weather forecasting at the outset of the twentieth century. A platform capable of raising instruments for sensing temperature, humidity, and wind conditions of the upper air, and a means of transmitting their readings automatically to a ground observer, were needed in order for data to arrive soon enough to be useful in making a current forecast.


By means of small balloons that could be sent aloft and tracked by a theodolite on the ground, the speed and direction of wind currents in the lower atmosphere were easily calculated. The development of larger and more durable balloons allowed flights up to an altitude of one hundred thousand feet. Instruments attached to the balloons recorded upper-air conditions, but the lack of an instantaneous communication system made them useless for immediate forecasting.