Charles Thomas Jackson, an American physicist, born in Plymouth, Mass., June 21, 1805. He devoted much attention to science in his youth, studied medicine under Drs. James Jackson and Walter Channing, and received the degree of M. D. from Harvard university in 1829. In 1827 and 1829 he made, in company with Francis Alger of Boston, a miner-alogical and geological survey of Nova Scotia, an account of which was published by them, together with a geological map of the province, in the " Memoirs of the American Academy of Arts and Sciences." In the autumn of 1829 he went to Europe, where he remained three years, studying in Paris. In 1831 he made a pedestrian tour through Switzerland, Piedmont, Lombardy, Tyrol, Bavaria, and Austria. He afterward visited the principal cities of Italy, and made a geological tour of Sicily and of Auvergne in France. In October, 1832, he embarked for New York in the packet ship Sully, taking with him an electro-magnet, two galvanic batteries, and other philosophical apparatus. During the voyage a discussion arose among the passengers, of whom Prof. S. F. B. Morse was one, on the subject of electro-magnetic experiments, and their applicability to telegraphic use.

Dr. Jackson asserts that during this discussion he pointed out the possibility of correspondence by means of electricity, and suggested several ways of accomplishing it. His plan as then developed in conversation, he declares, embraced the essential and peculiar features of the American telegraph patented in 1840 by Prof. Morse. Dr. Jackson also asserts that in the spring of 1834 he constructed and successfully worked, and exhibited to Francis Alger and other friends, a telegraph combining the peculiar features of that which he had invented on board the Sully, though he did not think it could be profitably brought into public use till the invention of the sustaining battery by Daniell in 1837 furnished the means of obtaining a long continued voltaic current of uniform strength. A controversy arose in 1837 between Morse and Jackson upon their respective claims, the evidence in regard to which was printed for the use of the court and counsel in subsequent trials of telegraph causes. In 1833 Dr. Jackson settled in Boston, and entered upon the practice of medicine, but in a few-years he abandoned it to devote himself to chemistry, mineralogy, and geology.

In 1836 he was appointed geologist of Maine, and directed to survey that state; and at the same time he was commissioned by Massachusetts surveyor of her public lands in Maine. In 1839 he was appointed geologist of Rhode Island, and in 1840 of New Hampshire. His surveys of these three states occupied respectively three, one, and three years, and his reports to the legislatures were published by them, with plates. Meanwhile he drew up a plan for a geological survey of the state of New York, which was adopted. In 1844 he explored the then unbroken wilderness on the southern shore of Lake Superior, and made known its mineral resources. In 1845 he again visited Lake Superior and opened mines of copper and discovered mountains of iron ore, which were explored by his assistants, and are now extensively wrought. In 1847 Dr. Jackson was appointed to superintend a geological survey of the mineral lands of the United States in Michigan, and he was thus engaged for two years, when, on a change of administration at Washington, the superintendence was transferred to another. His report of these labors was published in 1850, in 1 vol. 8vo. Dr. Jackson is one of the claimants of the discovery of anaesthetics.

His claims are substantially as follows: In 1834 he discovered that an alcoholic solution of chloroform, when made to act locally on a nerve, renders it insensible to pain; and that if a piece of lint saturated with a mixture of one part of chloroform and three parts of alcohol is inserted into the cavity of a painful tooth, it allays the pain at once, and by repeated applications completely destroys the sensibility of the nerves. Having long before experimented with exhilarating gas or protoxide of nitrogen, he resumed in 1837 his experiments with that gas in order to test the comparative effects of different modes of administering it; but the only new result he obtained was to satisfy himself that the temporary insensibility which it sometimes produces is due in a greater or less degree to partial asphyxia. Subsequently, but previous to the winter of 1841-'2, having received some perfectly pure sulphuric ether, he tried its effects upon himself, administering it with a mixture of atmospheric air, and inhaled it to such an extent as to lose all consciousness, without suffering any of the dangerous or disagreeable consequences that had hitherto attended the inhalation of impure sulphuric ether unmingled with atmospheric air.

In the winter of 1841-'2 he inhaled ether vapor for relief from the very severe pain occasioned by the accidental inhalation of chlorine. The relief he experienced led him to infer "that a surgical operation could be performed on a patient under the full influence of sulphuric ether, without giving him any pain." Dr. Jackson's claims to the discovery of anaesthetics, disputed by Dr. W. T. G. Morton and Dr. Horace Wells, gave rise to a long controversy. In 1852 a memorial was presented to congress, signed by 143 physicians of Boston and its vicinity, ascribing the discovery exclusively to Dr. Jackson. About the same time the question was investigated by a committee of the French academy of sciences, and on their report the academy decreed a prize of 2,500 francs to Dr. Jackson, and another of 2,500 francs to Dr. Morton. M. Elie de Beaumont remarked in a letter to Dr. Jackson, dated May 17, 1852: "In point of fact, the academy of sciences decreed one of the Monty on prizes of 2,500 francs to you for the discovery of etherization, and it has decreed a prize of 2,500 francs to M. Morton for the application of this discovery to surgical operations." Dr. Jackson has received orders and decorations from the governments of France, Sweden, Prussia, Turkey, and Sardinia. His scientific discoveries have been very numerous.

Besides the geological reports above mentioned, he has furnished many scientific communications to the "American Journal of Science and Arts," to the French Comptes rendus, and to the Bulletin de la societe geologicale de France. He has also published the results of chemical researches on the cotton plant, the tobacco plant, on Indian corn, and on 38 varieties of American grapes in the United States patent office reports, and a "Manual of Etherization, with a History of the Discovery " (1863).