ARMSTRONG, John, Scottish poet and physician, born about 1709, died 1779. After studying medicine in Edinburgh he settled in London. In 1744 he published his chief work, the _Art of Preserving Health_, a didactic poem. This work raised his reputation to a height which his subsequent efforts scarcely sustained. In 1746 he became physician to a hospital for soldiers, and in 1760 he was appointed physician to the forces which went to Germany. After his return to London he published a collection of his _Miscellanies_, which contained, however, nothing valuable. He afterwards visited France and Italy, and published an account of his tour under the name of Lancelot Temple. His last production was a volume of _Medical Essays_.
ARMSTRONG, William George, Lord, engineer and mechanical inventor, born at Newcastle-on-Tyne, 10th Nov., 1810. He was trained as a solicitor, and practised as such for some time. Among his early inventions were the hydro-electric machine, a powerful apparatus for producing frictional electricity, and the hydraulic crane. In 1847 the Elswick works, near Newcastle, were established for the manufacture of his cranes and other heavy iron machinery, and these works are now among the most extensive of their kind. Here the first rifled ordnance gun which bears his name was made in 1854. His improvements in the manufacture of guns and shells led to his being appointed engineer of rifled ordnance under Government, and he was knighted in 1858. This appointment came to an end in 1863, since which time his ordnance has taken a prominent place in the armaments of different countries. He was made a peer, as Baron Armstrong, in 1887. He died 27th Dec., 1900.
ARMSTRONG GUN, a kind of cannon, so called from its inventor. It has an inner tube or core of steel, rifled with numerous shallow grooves, the tube being surrounded by a jacket of spirally-coiled bars of wrought iron, so disposed as to bring the metal into the most favourable position for the strain to which it is to be exposed. His first guns were small, but larger ones were soon made, and afterwards those of the very highest calibre. The breech-loading principle was also adopted in them, and special provision to effect this satisfactorily was invented by him. The improved shells introduced by him were of the elongated and pointed type now so well known, the charge being inserted in a special chamber behind the bore.