_Dentistry._--George Washington had false teeth, and it is said that the teeth of some of the mummies of Egypt had gold fillings, but it remained for the Nineteenth Century to establish dentistry as an art, and its influence in securing better mastication and digestion of food, more sanitary mouths and shapely faces, cannot be estimated. Few people can be found to-day who have not either filled teeth, bridge work, gold caps, or artificial sets of teeth. The most important advance in the art was in the invention of the rubber plate for holding the porcelain teeth. This was the invention of J. A. Cummings, and was covered by him in his patent No. 43,009, June 7, 1864. In more recent years “bridge-work” represents the most important advance. In this practice one or more artificial teeth are firmly held in the place of missing teeth by a strong bridge-piece of metal, which at its ends is anchored to the adjacent natural teeth. This was first done by Bing (British Pat. No. 167, of 1871), and was afterwards patented in somewhat different form in the United States by J. E. Lowe, No. 238,940, March 15, 1881, No. 313,434, March 3, 1885, and Richmond, May 22, 1883, No. 277,933. Porcelain and gold crowns and dental pluggers run by electricity represent other important advances in this art. It is said that there are 20,425 dentists in the United States, and that in 1899 they employed in their practice 20,499,000 false teeth. _Artificial Limbs._--With the successful work of the surgeon came the effort to repair, as far as possible, the loss of the limb. Until about the middle of the Nineteenth Century the survivor of an operation was an unsymmetrical, unique, and pitiful object. The peg-leg of Peter Stuyvesant lives in history, and the arm-hook of Capt. Cuttle is familiar to every reader. The first United States patent for an artificial leg was granted to B. F. Palmer, Nov. 4, 1846, No. 4,834. Wooden legs with a restricted back and forward ankle motion and a spring, were constructed by A. A. Marks from 1853 to 1863. On Dec. 1, 1863, a patent, No. 40,763, was granted to Mr. Marks for the use of sponge rubber for constructing artificial feet and hands that dispensed with the articulated joints, and made a great improvement. In patent No. 366,494, July 12, 1887, to G. E. Marks, the foot and leg portion of a wooden leg are made from wood which grows with a crook, as at the root of a tree, where the strength and lightness of a continuous natural grain is obtained at the instep. About 300 patents have been granted for artificial legs and arms. Modern improvements have extended to every detail of construction, and so perfect to-day is the average wooden leg that it is hardly to be detected. Men with wooden legs ride horseback, are expert users of the bicycle, and have even performed feats on the tight rope. The inventor’s genius has not stopped at repairing limbs, however, for artificial eyes, artificial ear drums, the audiphone, foot