an instrument for laying down and measuring, with accuracy and despatch, angles upon paper, and by which the use of the line of chords is superseded. This instrument is variously formed, such as the graduated semicircle, the rectangular ruler with graduated edges, and other more expensive contrivances.

PROUT, SAMUEL, a great painter in water-colours, was born at Plymouth in September 1783. His education in art was obtained by a patient and enthusiastic study of nature. He spent whole summer days in drawing the quiet cottages, rustic bridges, and romantic water-mills of the beautiful valleys of Devon. He even made a journey through Cornwall, to try his hand in furnishing sketches for Britton's Beauties of England. On his removal to London in 1805, a new scene of activity opened up before Prout. It now became his endeavour to correct and improve his style by the study of the works of the great masters. A great part of his time was also devoted to maintaining himself by means of his art. He painted marine pieces for Palser the printseller. He received pupils, and published many drawing-books for learners. He was likewise one of the first who turned to account in his profession the newly-invented art of lithography. In spite of all this industry, however, it was not until about 1818 that Prout discovered his proper sphere. Happening at that time to make his first visit to the Continent, and to study the quaint streets and market-places of continental cities, he suddenly found himself in a new and enchanting province of art. All his faculties feeling themselves in their congenial element, sprung into unwonted power and activity. His eye readily caught the picturesque features of the architecture, and his hand put them down upon canvas with unsurpassed felicity. The composition of the pictures was exquisitely natural; the colour exhibited "the truest and happiest association in sun and shade;" the delicately-carved remnants of ancient architecture were copied with fond minuteness; and the solemnity of great cathedrals was brought out with striking effect. Encouraged by this success, Prout continued most enthusiastically to pursue that path upon which he had unexpectedly come. At the time of his death, in February 1832, there was scarcely a nook in France, Germany, Italy, and the Netherlands where his quiet, benevolent, observant face had not been seen search- ing for antique gables and sculptured pieces of stone. In Venice especially there was scarcely a pillar which his eye had not lovingly studied and his pencil had not dexterously copied. (See a Memoir of Prout, by John Ruskin, in the Art-Journal for 1849.)

Prout, William, a distinguished physician, was born in 1786, and took the degree of M.D. at Edinburgh. Settling in London, he began to apply chemistry to his professional studies. The results of his investigations were published in Thomson's Annals of Philosophy, the Philosophical Transactions, the Philosophical Magazine, and other scientific journals. They also appeared in separate treatises. An Enquiry into the Nature and Treatment of Gravel, Calculus, and other Diseases connected with a deranged operation of the Urinary Organs, was produced in 1821. Not long afterwards he published all his discoveries in a collected form, in a treatise On the Nature and Treatment of Stomach and Renal Diseases. By these and other labours Prout attained to a position of eminence. He was employed to write a Bridgewater essay on Chemistry, Meteorology, and the Function of Digestion, considered with reference to Natural Theology. So successful was his work on Stomach and Renal Diseases that it reached a fifth edition in 1848. At the time of his death in 1850, he was a fellow of the Royal College of Physicians of London and also of the Royal Society.