1803, but relinquished it in 1810, to become a partner with his brother in the mercantile house of William B. Swett & Co. in Boston, having in the mean time married a daughter of the eminent merchant, the late Hon. William Gray. Soon after the breaking out of the war of 1812 he was active in organizing a volunteer corps in Boston, under the name of the New England Guards, of which he was the first commander, and which, under his lead, rendered important service in defence of our coast and harbor. Joining the United States Army as a volunteer, in 1814, he served as a topographical engineer on the staff of General Izard, with the rank of Major. After the declaration of peace he was an aid-de-camp to Governor Brooks, and was ever afterwards known as Colonel Swett. He had a strong taste for military service, and devoted not a little study to the science of war, even to the latest years of his life. Few men followed the campaigns of the late Rebellion with more intelligent and patriotic ardor, or were more ingenious and fertile in the suggestion of whatever might contribute to the comfort, safety, and success of the Union soldiers. He was a member, successively, of the Common Council and of the School Committee of Boston, and for three years one of its Representatives in the Legislature. He was a frequent contributor to some of our magazines and newspapers; and, on his return. from Europe, whither he had gone about the time of Napoleon's return from Elba, he published in the Boston Daily Advertiser an account of his tour, and of the events he had witnessed during the memorable Hundred Days. His principal, if not his only, independent publication, however, was an elaborate account of the Battle of Bunker Hill, in a pamphlet, which went through more than one edition. He was elected into the Academy in May, 1813.

Of his five children, two sons and a daughter survive him; but his wife died in 1844, and his eldest son, a Unitarian clergyman of many remarkable gifts, in 1843. Colonel Swett bore his bereavements and infirmities with a brave heart; and his familiar figure, though sorely bent by age, was seen in our streets, and at the meetings of our own Academy, until within a few months of his death.

HENRY DARWIN ROGERS, for many years one of our most distinguished Resident Fellows, and whose name was, in consequence of his change of abode, transferred to the Associate list two years ago, died at Shawlands, near Glasgow, upon the very day of our annual meeting last year, namely, on the 29th of May, 1866. Born in Phila

delphia on the 1st of August, 1808, he had not completed his fiftyeighth year.

He was the third in age of four brothers, only two of whom survive, who, inspired and guided by their father, Dr. Patrick Kerr Rogers, Professor of Natural Philosophy and Chemistry in William and Mary College, Virginia, as if by mutual agreement, all gave their lives to the cultivation and teaching of physical science. From his youth, the subject of the present notice evinced so decided a predilection for these studies and became so proficient in them, that, in his twenty-second year, he was made Professor of Physics and Natural History in Dickinson College, at Carlisle, Pennsylvania, where, at the same time, he edited a periodical called a "Messenger of Useful Knowledge." Here he began his first independent studies in structural and dynamical geology, in which he was destined greatly to excel.

Seeking better opportunities, he soon resigned his chair, and passed a year in England, studying chemistry under the late Professor Turner, and accompanying the late De la Beche in his geological explorations. Returning to Philadelphia, he devoted his whole time to scientific investigations. In conjunction with our other lately deceased associate, Professor Bache, he made and published a valuable series of analyses of the ashes of coal; and he aided his brother, our own William B. Rogers, in experiments upon "the laws of the Voltaic battery" (published in Silliman's Journal), and in preparing two memoirs upon "the Tertiary Formations of Eastern Virginia," which were published in the Transactions of the American Philosophical Society. At the request of the Council of the British Association for the Advancement of Science, he prepared a report on the Geology of North America, which was printed in the third Annual Report of that body, and was in part republished in this country in Bradford's edition of Murray's Encyclopædia of Geography.

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His first systematic geological labor was that of conducting the surof the State of New Jersey, of which he published a report in 8vo, with a geological map. While thus engaged a similar survey of the great State of Pennsylvania was provided for by the Legislature, and placed under his direction. This, the most important scientific labor of his life, was commenced early in the year 1836, and, with various interruptions and embarrassments growing out of legislative inaction, was completed by him in the spring of 1855. The fruits of these prolonged labors have been given to the world in his great work en

titled "Geology of Pennsylvania, Government Survey; with a General View of the Geology of the United States, Essays on the Coal Formation and its Fossils, and a Description of the Coal Fields of North America and Great Britain." This great work is contained in three royal quarto volumes, illustrated by forty-five sketches of scenery, forty-seven geological sections, two plates of columns of strata, twenty-three plates of coal fossils, and seven hundred and seventy-eight wood engravings of views and diagrams of coal-beds, &c., and accompanied by a general geological map of the State, a special map of the anthracite coalbasins, and two large sheets containing the nine general sections, elucidating the geological map.

During the early progress of this work he produced, in conjunction with his brother, William B. Rogers, the well-known memoir "On the Physical Structure of the Appalachian Chain," unfolding certain dynamical laws which have regulated the elevation of mountain chains. About the same time (1842) he published an elaborate paper on the origin of the Appalachian coal strata, bituminous and anthracitic, containing much original observation and important speculative views; his brother pursuing a parallel system of investigations in Virginia, where the formations are identical with those of Pennsylvania. The result of the labor of these two brothers, carried on for ten years together, was the grand discovery of the structural unity of central North America, between the Appalachian chain and the Rocky Mountains, the great lakes and the Delta inclusive; a fact of such importance that it must serve in future as a guide to all general researches; since it is not reasonable to suppose that so large a portion of the earth's surface should have been formed in any other than the normal mode. Occupying at this time the chair of Geology in the University of Pennsylvania, he gave instruction in that science in the intervals of his labors on the State Survey. He also delivered courses of lectures at the Lowell Institute and elsewhere; on all such occasions showing that readiness and felicity of diction, without the use of notes, for which he had always been remarkable.

He was one of the founders, and an early President, of the American Association of Geologists, which, after an active and most useful career, expanded into the American Association for the Advancement of Science. Although chiefly devoted to geological research, Professor Rogers paid much attention to those sciences of which geology is the extended application, — Natural History, Climatology, and Physical Geography.

In 1855 he contributed to Keith Johnson's Physical Atlas the Geological Map of the United States and British North America; and the Chart of the Arctic Basin, with the accompanying letter-press, and the text of the somewhat later Geographical Atlas of North America, is from his pen. The philosophical questions arising from these studies especially interested him; indeed, the whole bent of his mind was in an eminent degree philosophical rather than technical.

In the year 1857, while in Edinburgh superintending the publication of his Geological Report, he was appointed Regius Professor of Natural History and Geology and Curator of the Hunterian Museum, in the University of Glasgow, and thenceforth became a resident of Scotland. While devoting himself to the duties of his chair, he became associated with Jardine and Balfour in the editorship of the Edinburgh New Philosophical Journal, contributed a paper on "The Laws of Structure of the more disturbed Zones of the Earth's Crust" to the Transactions of the Royal Society of Edinburgh, and found time for a number of scientific essays, published in Blackwood and Good Words, as well as for occasional lectures on his favorite geological topics in London, Edinburgh, and elsewhere.

On revisiting, as it proved for the last time, his native country, in 1855, his friends were concerned to see that his health had given way under his prolonged and excessive labors, overtasking a constitution, elastic indeed, but not naturally robust. He returned to Glasgow, reinvigorated it was thought; but we soon heard, with sorrow, that he

was no more.

Although the eminent position in geology held by our late associate, and somewhat of the nature and dominant influence of the general views of the associated brothers, may be inferentially gathered from this biographical sketch, yet we are, for obvious reasons, prevented from entering upon their consideration here, nor indeed is it necessary to do so. Of him whom we have lost, suffice it to record, here, in simplest and briefest phrase, that he was a most accomplished investigator, a graceful and persuasive teacher, and fascinating companion; that to rare powers and attainments he added a lively sympathy in all the interests of humanity, and a courageous devotion to whatever he deemed just and true.

ALEXANDER DALLAS BACHE, born in Philadelphia on the 19th of July, 1806, was the son of Richard Bache, and grandson of the only daughter of Benjamin Franklin. His mother was Sophia Dallas,

daughter of Alexander J. Dallas, of a family also well known in the history of this country. Remarkable from early boyhood for his aptitude in the acquisition of learning, he was appointed a cadet in the National Military Academy at West Point before he had completed the fifteenth year of his age. Here, although the youngest pupil, he soon reached a high grade of scholarship, and maintained it throughout the course, graduating in 1825 at the head of his class; a class of such marked ability that it furnished no less than five successful candidates to the corps of Engineers. It has been mentioned as a solitary instance in the history of the Academy, noted for its rigid discipline, that he passed through the entire course of four years without a single mark of demerit, and, what may be hardly less uncommon, without calling forth the least manifestation of envy. Indeed his classmates, as well as the teachers, seem to have taken pride in the high character and scholarship of the youthful cadet. His room-mate, several years his senior, and by no means noted for studious or regular habits, assumed the office of guardian, sedulously protecting him from interruption or intrusion during the hours of study, and, it is said, habitually excused his own shortcomings by pleading the importance of the duty he thus performed. Not that young Bache himself needed a guardian, except for his tender years and to protect him from hindrance on the part of others. Sensible beyond his years of the responsibility which would devolve upon him in the support of his widowed mother and her younger children, and of the obligations incurred in his education at the National School, he resolved from the first to exert his utmost energies, doubtless not unconscious, moreover, that, as a descendant of Franklin, something more than ordinary might be expected from him. Upon such a mind as his, the adage noblesse oblige could not but have a powerful influence.

Upon his graduation he was selected, on account of his high standing, to remain at the Academy as Assistant Professor, a position which gave him a desired opportunity to review and extend his studies. But after a year in this service he was, at his own request, assigned to engineering duty at Newport, Rhode Island, under the late General, then Colonel Totten. Here for two years he was engaged in constructing fortifications, devoting his extra hours to the study of physics and chemistry.

The most important event of this period, however, and doubtless the most influential upon his future success, was the acquaintance and