"Take me to Washington," he said, "I must work while there is time."
And there, lying in agony on his bed, for three weeks he dictated steadily to stenographers on a subject which required the utmost concentration. His indomitable will alone supported him, and a week after the last word had been written, came the end. Verily, there was a man!
The last of the great American astronomers whom we shall mention here is Edward Charles Pickering, whose name is so closely connected with the development of the great observatory at Harvard. Born at Boston, and educated at the Lawrence Scientific School, his first work was in the field of physics, but in 1876, he was appointed professor of astronomy and geodesy, and director of the Harvard observatory, which, under his management, has become of the first importance. His principal work has been the determination of the relative brightness of the stars, and many thousands have been charted. On the death of Henry Draper, the study of the spectra of the stars by means of photography was continued as a memorial to that great scientist, and the results obtained have been of the most important character, including a star map of the entire heavens. Other phases of the science of scarcely less importance have been carefully developed, and the work which has been done under Pickering's direction, is second to none in the history of the science. Not satisfied with the Northern hemisphere, a branch has been established in Peru, in which the observatory's methods of research have been extended to the south celestial pole. So for eighteen years and more, it has kept ceaseless watch of the heavens, with an accuracy of which the world has hardly a conception. For this great work the scientific world must pay tribute to the genius and perseverance of Edward Charles Pickering.
The second department of science claiming our attention is that of paleontology. Here one of the most eminent of American names is that of Othniel Charles Marsh. A graduate of Yale and firmly grounded in zoology and kindred sciences by a course of study at Heidelberg and Berlin, he returned to the United States in 1866 to accept the chair of paleontology which had been established for him at Yale. The remainder of his life was devoted to the original investigation of extinct vertebrates, especially in the Rocky Mountain regions. In these explorations, more than a thousand new species of extinct vertebrates were brought to light, many of which possess great scientific interest, representing new orders never before discovered in America. So important was this work that the national geological survey undertook the publication of his reports, which formed the most remarkable contributions to the subject ever written in this country, attracting the attention and admiration of the whole scientific world.
Associated with Marsh as paleontologist for the Geological Survey was Edward Drinker Cope, whose work was second only to the older man's in importance. He also devoted much of his attention to the exploration of the Rocky Mountain region, and found that there, in the strata of the ancient lake beds, records of the age of mammals had been made and preserved with a fulness surpassing that of any other known region on earth. The profusion of vertebrate remains brought to light was almost unbelievable. Prof. Marsh, who was first in the field, found three hundred new tertiary species between 1870 and 1876, besides unearthing the remains of two hundred birds with teeth, six hundred flying dragons, and fifteen hundred sea serpents, some of them sixty feet in length. In a single bed of rock not larger than a good sized lecture room, he found the remains of no less than one hundred and sixty mammals.
It was this work which Prof. Cope took up and carried forward. Its importance may be appreciated when it is stated that among these remains are found examples of just such intermediate types of organisms as must have existed if the succession of life on the earth has been an unbroken lineal succession. Here are snakes with wings and legs, and birds with teeth and other snakelike characteristics, bridging the gap between modern birds and reptiles. The line of descent of the horse, the camel, the hippopotamus and other mammals has been traced to a single ancestor, the result being the proof of the theory of evolution.
The whole work of American paleontology has, of course, been along these lines. Agassiz himself was a living and vital force in it, as were such men as Joseph Leidy and H. F. Osborne.
It is a remarkable fact that one of the few truly original and novel ideas the past century can boast, and the one which has had the deepest influence on geology, had its origin in the brain of an illiterate Swiss chamois hunter named Perraudin. Throughout the Alps, on lofty crags, great bowlders were often found, which had no relation to the geology of the region and which were called erratics, because they had evidently come there from a distance. But how? Scientists explained it in many ways, but it remained for the mountaineer to suggest that the bowlders had been left in their present positions by glaciers. The scientific world laughed at the idea, but ten years later, it was brought to the attention of Louis Agassiz; he investigated it, became a convert, and saw that its implications extended far beyond the Alps, for these erratic bowlders were found on mountains and plains throughout the northern hemisphere. Agassiz found everywhere evidences of glacial action, and became convinced that at one time a great ice cap had covered the globe down to the higher latitudes of the northern hemisphere. So came the conception of a universal Ice Age, now one of the accepted tenets of geology.
The dean of American geologists was Benjamin Silliman, who, at the very beginning of the nineteenth century, took up at Yale University the work which he was to carry on so successfully for more than fifty years. As an inspiring teacher he was scarcely less successful than Agassiz at a later day. His popular lectures began in 1808 and soon attracted to New Haven the brightest young men in the country. Among them was James Dwight Dana, who was to carry on most worthily the work which Prof. Silliman had begun.