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command of the arsenal in 1854, and of the one at Baton Rouge, La., in 1855-'6. Although columbiads made by his method showed greater power of reliance than those that were cast solid, yet they failed under severe tests, and, as the result of a series of experiments at Pittsburg in 1850, he recom- mended that no more guns of large calibre should be made of that pattern. In 1857-'8 he experi- mented with a pressure-gauge of his invention, con- sist ing of a piston working in a hole bored into the wall of a gun and acting on an indenting tool, for the purpose of determining the pressure in the bore at different points. He devised a new form of columbiad which was determined on the hypothesis that the pressure is inversely as the square root of the space behind the shot. The first 15-inch Rod- man gun was completed in May, 1800. In the trials, mammoth (or very large-grained) powder, and pow- der in perforated'cakes, were also tested, and in the following year the mammoth powder was adopted for heavy ordnance. The perforated cake powder for rifled cannon of large calibre was at once adopted by the Russian government, which ob- tained specimens from Fortress Monroe in 1800, and soon afterward came into use in Prussia, and more recently the military authorities in England decided on using the mammoth powder, there called pebble powder, in their big rifled guns. Rodman, who had reached the grade of captain of ordnance on 1 July, 1855, and was promoted major on 1 June, 180:!, was in command of Watertown arsenal during the civil war. being detached at in- tervals for various services, especially to supervise the manufacture and trials of 12-inch rifled and 20-inch smooth-bore cannon. Many 13- and 15-inch li'i'dinan guns were made during the war for the monitors and the forts along the coast. The meth- od of cast in ir about a hollow core and cooling the metal from the inside was applied to shells as well as to cannon, and from 27 Sept., 1864, he was en- gaged in supervising the manufacture of ordnance and projectiles by this method. He originated the idea of making heavy guns without preponderance at the breech, on which plan all the heavy east-iron cannon were subsequently constructed in the Unit- ed States. In March, 1865, he was brevetted lieu- tenant-colonel, colonel, and brigadier-general for his services in the ordnance department. He was placed in command at Rock Island on 4 Aug., 1865, and promoted lieutenant-colonel on 7 March. 1807, served on various boards for testing inventions in lire-arms, and at the time of his death was engaged in completing the arsenal at Rock Island, which was constructed at his suggestion and under his superintendence.

RODNEY, Cæsar, signer of the Declaration of Independence, b. in Dover. Del., 7 Oct., 1728; d. there, 29 June, 1784. An old family manuscript says : "It hath been a constant tradition that we came into England with Maud, the empress, from foreign parts ; and that for service done by Rode- ney, in her wars against King Stephen, the usurper, she gave them land within this kingdom." A painted monument in the village of Rodney-Stoke, Somerset co., bears the arms of this family. His grandfather, William Rodney (1652-1708), came from Bristol, England, to Philadelphia soon after William Penn had settled Pennsylvania, located at Lewes on the Delaware, where in 1689 he was elect- ed sheriff of Sussex county, and removed to Dover, Kent co., Del., where he held local offices. In 16!)8-'9 he was a member of the assembly and again in 1700-'4, serving as speaker in t lie last year, when he was made justice of the peace. In 1698-'9 he was a member of William Penn's council, and in 1707 was appointed justice of New Castle. Caæsar inherited a large estate from his father, Caæsar (1707-'45). In 1755-'8 he was high sheriff of Kent county, and at the expiration of his term he was made a justice of the peace and judge of all the lower courts. In 1 750 he was a cap- tain in the county militia. In 1759 he was a superintendent for the printing of £27,000 of Delaware currency, and commis- sioner for the support of a company raised for the French and In- dian war. In 1762-'3 he represented Kent county in the assem- bly, was recorder in 1764, and justice of the peace in 1764-'6. In

1765 he was sent as a

delegate to the stamp-act congress at New York, and on the repeal i if that act he was one of three commissioners that ere appointed by the legislature of Delaware to frame an address of thanks to the king. In 1760 he was made register of bills, and in 1707, when the tea-act was proposed by the British parliament. tin- Delaware assembly appointed him. with Thomas McKean and George Read, to formulate a second address to the king, in which armed resistance to tyranny was foreshadowed. In 1769 he was superintendent of the loan office, and from 1769 till 1778 was an associate justice. In 1770 he was clerk of the peace, and in 1770-'4 Dedimus potestatimus. In 1772 he was a commissioner to erect the state-house and other public buildings in Dover. A bill having been introduced into the colonial assembly for the better regulation of slaves, Mr. Rodney warmly supported a motion that the bill be so amended as to prohibit the importation of slaves into the province. The amendment was negatived by only two votes. When fresh aggressions of the British ministry disappointed the expectations of the colonists, Mr. Rodney and his former colleagues were assigned the task of presenting the complaints of the freemen of Delaware to the sovereign. These pacific measures failing to secure a redress of grievances, the colonies entered into a correspondence regarding their common defence. Mr. Rodney became chairman of the committee of safety of Delaware, and in 1774. meetings of the people having been held at New Castle and DOMT to demand the assembling of a convention, he issued a call as speaker of the assembly for the representatives of the people to meet at New Castle on 1 Aug. He was chosen chairman of the convention, and was elected a delegate to the Continental congress, in which he was a member of the general committee to make a statement of the rights and grievances of the colonists. In March, 1775, he was again elected to congress after the assembly, by a unanimous vote, had approved of his action, and that of his colleagues, at the 1st congress. In May he was appointed a colonel, and in September he became brigadier-general, of Delaware militia. In 1776 he was alternately in his seat in congress, and at work in Delaware, stimulating the patriots and repressing the royalists. When the question of independence was introduced in congress, Mr. Rodney, having obtained leave of absence, went through the southern part of Dela-