Physicians, and of the Royal Society of Edinburgh. Engaging, as most of the young physicians of Edinburgh were in the habit of doing, in dispensary practice, he was painfully impressed with the great need of better ventilation in the houses of the poor, and the lessons taught him by his experience there were never forgotten. While a student in the university he had been assistant to Sir John Leslie, then Professor of Natural Philosophy in the university, and after his graduation he had taught independent classes in chemistry, until he was called by Dr. Hope to assist him in his chemical course in 1827, and for five years had the entire charge of the classes of practical and analytical chemistry in the university. In 1832 he determined to resume his independent classes, and erected a class-room and laboratory larger than any in Edinburgh, which he opened in 1833, and for the next seven years had about three hundred pupils annually in his chemical classes. In 1836 he was called to make such alterations in the old House of Commons as should secure its better ventilation, and in 1839 superintended similar changes in the House of Peers. When the Houses of Parliament were burned in 1840, he was called from Edinburgh to direct the ventilation of the new Houses. For five years he continued in this work, though under serious difficulties and constant annoyance from the numerous changes to which his plans were subjected by the builders. He finally refused to be responsible for the success of the ventilation unless his plans could be adhered to strictly, and he himself sustained in enforcing them. As a result of this, the House of Commons, after a sharp contest, accorded to Dr. Reid all that he asked, while the House of Peers withdrew their House from his jurisdiction. He never acted subsequently at the Houses of Parliament, except under protest, gaining a public hearing at the bar of the House of Commons in 1852, and carrying an award against the Government at an arbitration the following year. Dr. Reid was more fortunate in being freed from interference in the application of his plans of ventilation in the construction of St. George's Hall, Liverpool, the largest public building in that city, containing upwards of one hundred rooms, the ventilation of which was perfect even when most densely crowded. His plans were also introduced into numerous public buildings, manufactories, and private habi

tations.

His system was based upon a new estimate of the quantity of air required for respiration, and of the varied circumstances that modified this amount. Its leading features in public buildings consisted in his treating the whole structure as a piece of apparatus, and securing, whenever necessary, the power by engines, shafts, or otherwise, of introducing an atmosphere with the most gentle possible impetus, with the greatest diffusion practicable, and of the quality in respect to temperature and moisture best adapted to the wants and numbers of

the audience, while the most scrupulous care was observed in taking the air from the purest accessible source, and in reducing the amount of impurities when present in such quantities as to require attention. He made ventilation a primary instead of a secondary question. His difficulties in securing thorough ventilation and pure air in the old House of Commons, which had the river Thames, with its noisome vapors on one side, a pestilential graveyard on the other, and a hundred and fifty offensive factories in the immediate vicinity, forced the question of sanitary improvement upon his attention, and in 1842 he was appointed one of the "Com missioners to inquire into the state of large towns and populous districts in England and Wales," better known as the "Health of Towns' Commission." In this capacity he gave, under the sanction of the Privy Council, a course of lectures at Exeter Hall to one thousand teachers on the necessity and means of improving the sanitary condition of densely-populated districts. He also visited and superintended the introduc tion of improved methods of ventilation and sewerage in most of the cities of the United Kingdom, especially in court-houses, churches, schools, ships of war, prisons, and tenementhouses. He also made a report to Government concerning the better ventilation of mines. So zealous a sanitary reformer could not fail to arouse the dislike and hostility of those who had a vested interest in the wrongs which he so fearlessly exposed; and it is no matter of wonder that the "London Times" always the organ and defender of hereditary and privileged abuse, should have sought, by the most reckless falsehoods and malignant misrepresentations, to crush him. In this effort it was unsuccessful; its falsehoods and slanders, though never retracted, were nailed to the counter by the reports of the Committees of the House of Com mons, the investigations of the Admiralty and the civic authorities, and the testimony of the most eminent men of the nation, and in the end Dr. Reid gained in reputation from the abuse of the "Times." Having occasion to visit St. Petersburg, on a mission connected with the ventilation of some of the Government buildings there, Dr. Reid received letters from Lord John Russell to the Russian authorities, and was received with great attention by the Emperor Nicholas, and requested to direct the ventilation of the public buildings and vessels of war. The present Emperor subsequently charged him with the application of his system of ventilation to the war steamer General Admiral, built in New York.

In 1856 Dr. Reid came to the United States, bearing official letters to the President from Lord John Russell, and interested himself on the subject of quarantine and on the improve ment of the sanitary condition of our large cities. He subsequently removed to the West and after filling for a time a professorship of applied chemistry in the University of Wiscon sin, made his residence at St. Paul, Minn. His

admirable qualifications for such a service led the U. S. Sanitary Commission to select him as one of its medical inspectors. He entered with great zeal upon his duties, and was of eminent service to the army in urging and securing larger camping grounds, better ventilation in the tents, and a more efficient sanitary police in the camps and hospitals, as well as in the direction of the necessary supplies to supplement the Government provisions for the sick soldiers. While engaged in this benevolent work he was seized with congestion of the lungs, and died at Washington after a brief illness.

The following list_comprises Dr. Reid's principal works: "An Introduction to the Study of Chemistry," Edinburgh, 1825; "Rudiments of the Chemistry of Daily Life," Edinburgh, London, and New York, many editions, 18361854; "Text-Book for Students of Chemistry," three editions, Edinburgh, 1834-1839; "Elements of Chemistry, Theoretical and Practical," three editions, Edinburgh, 1832-1839; "The Study of Chemistry as a General Branch of Education," two editions, London, 1842; "Illustrations of Ventilation," London, 1844; "Ventilation of the House of Commons," printed for the Government, 1837; "Ventilation of the Niger Steamships," printed for the African Colonization Society, 1841; "A Reply to the Times and Atheneum," London, 1846; "Ventilation of St. George's Hall, Liverpool, printed for the corporation of Liverpool," 1855; "Ventilation in American Dwellings," New York, 1858 and 1863; "A Short Plea for the Revision of Education in Science," St. Paul, 1861. In addition to these he had contributed the article "Ventilation" to the Encyclopedia Britannica, and numerous papers to scientific journals in Great Britain and the United States, and to the publications of the Smithsonian Institution, the U. S. Sanitary Conventions, and to Parliamentary and Legislative documents.

REVOLVING TURRETS constitute the essential feature of American armored vessels. The principle seems equally applicable to land fortifications. The inventor of this system is Theodore R. Timby, who was born in Dutchess County, N. Y., April 5th, 1822. He received the school and academical education usual for the sons of substantial farmers. The natural bent of his mind was toward mechanical inventions. When only sixteen years old he constructed a model, substantially like those now in use, of a floating dry dock; this was submitted to persons whom he supposed capable of deciding upon its practical value. They admitted the idea to be ingenious, but said that its execution was impracticable. The invention was dropped. Years after it was reinvented by others; but the floating docks now in use contain nothing essential which was not involved in the invention of the young resident of a country village. Another invention, an improvement upon the turbine water-wheel, proved useful and profitable. In all, Mr. Timby has obtained patents for more than a score

of valuable inventions. The most important of these is that of the Revolving Turret, as applied to naval and military purposes. The idea of this was conceived while he was a mere boy. The original model, constructed in 1841, and still in his possession, contains the germ of the whole invention. On the 18th of January, 1843, he filed his first caveat for the invention in the United States Patent Office. The specifications were "for a Revolving Metallic Tower, and for a Revolving Tower for a Floating Battery to be propelled by steam." It would be difficult, in so few words, more clearly to describe our "monitors and the whole class of turreted vessels which has succeeded them. Meanwhile he had been engaged in constructing a large iron model. This was completed in the spring of 1843, and was publicly exhibited in New York and elsewhere. This is on record in the New York "Herald" and "Evening Post" of June 7th, 1843, and in many other newspapers of the time. For some years he continued to develop his invention still further, and filed additional specifications in the Patent Office. He made several models, one of which was presented to the emperor of China by our minister, Mr. Cushing.

Mr. Timby, from 1843 onwards, pressed his invention upon the attention of the American Government. Its practicability was admitted, but it was assumed to be wholly superfluous. The existing fortifications, it was said, were far more than were necessary. Once indeed, in July, 1848, a favorable report was made to Mr. Marcy, then Secretary of War, by Jefferson Davis, D. L. Yulee, F. H. Elmore, and Dixon H. Lewis, endorsed by Col. Bumford, Chief of the Ordnance Bureau. This official recognition is some years anterior to the time when Capt. Coles claims to have invented the turret. When the rebellion broke out, Mr. Timby sprung to the development and practical application of his favorite invention; he constructed a fifth model, embodying all the improvements to which he had devoted the energies of eighteen years. The patents which he had secured covered the broad claim "for a Revolving Tower for Offensive and Defensive Warfare, whether used on land or water." When therefore the "monitors" were to be built, the constructors at once recognized the validity of his claim, and paid him a liberal sum for the right to use his invention. These facts prove incontestably that he is the inventor of the revolving turret.

The general advantages of the revolving turret, even as already constructed, are apparent. It not only affords perfect protection to the guns and gunners, but enables each gun to be brought to bear upon every point of the circle within its range. But the turrets hitherto built embody only a small part of their offensive power as developed by the inventor. To explain this it will be more convenient to consider a turret for a land fortification, where

Exterior and interior walls of the Tower, with dome-shaped roof, K, revolving by the gearing F, upon the friction rollers G, G. Artillery Platforms, with guns mounted upon their carriages, which radiate from the common centre.

The Central Turret, revolving, independently of the Tower, upon the shaft b, b, by means of the rod and gearing D; on the left of the shaft is seen the circuit-closer, forming the connection between the galvanic battery and the conducting chains passing to each gun. Ventilators.

Casemates, with guns, independent of the Revolving Tower.

there is no limit to the possible size and thickness. The illustration on page 722 represents a cordon of three of these turrets arranged for the protection of a harbor. They are supposed to be one hundred feet in diameter, with two tiers of guns. They rest upon a structure of iron-clad masonry, in which are contained the magazines and steam engine. The diagram on page 720 presents a sectional view of a turret, cut down vertically through the centre so as to show the interior arrangements. Directly unber the dome-shaped roof is a platform resting upon a central shaft, which revolves independently of the turret, and not by means of the steam engine. This is the station of the commander during action. In the roof is a narrow opening through which, by means of a fixed telescope, he keeps watch of the enemy. At his hand is a wheel, connected by rods and gearing with the shaft so that he can turn the platform in any direction, and thus keep his telescope always pointed upon the object of attack. If this moves, he follows it, precisely as a sharpshooter with a telescopic rifle follows the course of a moving object. By an arrangement of signals he can also give any directions for the management of the vessel or of the guns. As the turret revolves each gun is for an instant brought in the course of every revolution directly in a line with the commander's telescope. If the gun is discharged at that instant, the ball must go straight to its mark. Provision is made for doing this with unerring certainty. Each gun in the act of passing under the vertical line of the telescope, is discharged by means of an electric current. This telescope being held pointing to the object of attack, every gun in the battery is really aimed by the commander. This automatic sighting and discharge are essential features of the invention; they obviate the uncertainty of aim, which is the main objection against the towers heretofore built. The commander aims and discharges every gun in his battery; the gunners have only to load, run the piece to the porthole, and place the fuse in the vent. This can be done in one minute. A turret of one hundred feet in diameter will give ample space for sixty guns in two tiers. If it revolves once a minute, which is equal to about three and a half miles an hour, its effective fire is sixty guns in a minute directed with unerring aim upon any point of the circle-an offensive power greater than that of any fortress in the world. For defensive power, such a turret can be made absolutely invulnerable. The "monitor" turrets are from nine to thirteen inches thick; but in a land turret, if one foot is not sufficient, there may be two or five. The only limit is the crushing weight of the structure upon the steel rollers on which it revolves. The main purpose of a land turret is for harbor defence. The illustration on page 722 shows the adaptation of a cordon of turrets for the protection of the harbor of New York. The point of defence is supposed to be the VOL. IV. 46 A

Narrows, where the channel is about onefourth of a mile wide. A tower is built upon each shore, and another is placed midway. An enemy approaching would be exposed, from the moment he came within range, to the concentric fire of these three forts, each capable of delivering sixty shot in a minute with an accuracy hitherto unknown in gunnery. To pass these forts he must come, with broadsides exposed, within one-sixteenth of a mile of the muzzles of one hundred and twenty guns, aimed with the precision of a telescopic rifle. Should he succeed in passing, his stern would be exposed, so long as he continued within range, to the fire of all the towers. The guns may be of the largest calibres, for it has been demonstrated that the heaviest ordnance can be discharged within a turret with less inconvenience than from the casemate of a fortress. It would seem that nothing that can float could sustain this fusillade for a quarter of the time in which the swiftest steamer would be exposed to it. A single hostile steamer once within range of New York, Boston, or San Francisco, could impose its own terms. To this system of turrets Mr. Timby therefore proposes to add a series of chains. These stretch from turret to turret, and are attached to windlasses turned by the steam engine within. Buoys are fastened to the chains, leaving their specific gravity just sufficient to sink them. In time of peace they lie quietly on the bottom, presenting no obstruction to navigation. On the approach of an enemy they are drawn up, not taut, but so as to hang swaying in the water at such a depth as to prevent the passage of a vessel; the greater part of their weight being supported by the buoys, almost their entire tensile strength is available as a barricade. These chains may be of any required size and number. They possess the character of an immense iron raft, sufficiently submerged to be wholly out of the reach of an enemy. The most powerful steamer striking them would merely sway them back, while its own momentum would be destroyed, and it would be helpless under the guns of the turrets. Outside of these chains it is proposed to stretch a line of torpedoes attached to a chain from tower to tower across the channel. These can be drawn directly under the vessel while detained, and exploded at the precise instant desired by the discharge of an electric current. This obviates the great practical defect in all systems in which torpedoes have been employed, that the discharge is a matter of chance. The diagram on page 722 shows the details of the system of turrets, chains, buoys, and torpedoes, which combines in itself all the elements of defensive warfare hitherto employed. Its cost for construction and maintenance must be less than that of stone fortresses. The defensive works of Charleston cost more than would be required to render New York impregnable to the combined navies of the world. Masonry having been shown to be useless against modern artillery, the sole

reliance must be upon earthworks and iron. Earthworks being liable to be captured by escalade, must be defended by a force nearly as great as the attacking one; and iron, it is believed, can in no way be as advantageously used as in the system of turrets and its adjuncts.

The plan for revolving turrets for vessels proposed by Mr. Timby is essentially the same as for those built upon land, modified only by the fact that there is a limit to the size and weight of a turret which can be borne by a vessel. The essential features of the automatic sighting and discharge are equally applicable to both.

CORDON OF REVOLVING TOWERS AND CHAINS FOR HARBOR DEFENCE.