CLEMENT W. COU MBE.
a much flattened univalve mollusk of the family Haliotide, allied to the keyhole limpets. It takes its name from its rough resemblance to the human ear, and is known as ormer and oreille de mer in the Channel Islands, where one species is exten sively used in making ornaments. These mol lusks in various species occur on rocky shores in all warm regions, and in California are called abalones. Their richly nacreous shells are used extensively for the making of buttons and fancy articles ; and in China and Malaya the animals are eaten fresh and also preserved as food in large quantitie.L Consult Cooke, 'Mollusks' (New York 1895).
an instrument used to strengthen the sensation of sound in the par tially deaf. The first mechanical contrivance for the purpose of improving the hearing was made by Dr. Yeardsley of London in 1848. Since that time, numerous curious devices have been invented. The unpopularity of these is due to their awkwardness in size and shape for portability. Before advising the use of such mechanical aids a careful diagnosis of the ear should be made, and the condition of the middle ear should be especially ascertained. In general these aids are apt to induce only temporary improvement and result eventually in more serious complications. The object of the ear-trumpet is to collect the sound waves and throw them into the ear in parallel waves. The curve of the collector or resonator— the reflector— must be more or less parabolic so as to give the maximum amount of sound at the entrance of the tube. For hearing at short distances Currier's consco-cylindrical tube is considered the best. It consists of a tube three and one-half feet long, which has a bone or hard rubber tip at one end while at the other is a bell-shaped mouthpiece made of the same material. The tip and mouthpiece are con
nected by an elastic spiral wire tube covered with rubber and over-spun with silk or mohair. The tube is conical, and the speaker must place his lips close to the mouth of the tube. The London hearing dome is made of metal, of the same variety as that used in musical instru ments; the Akou concentrator intensifies as well as concentrates sound, and is made of bell-metal; the Hearzvell church phone is of hardened rub ber and partly collapsible. It is of great use in long distance hearing, as are also the audiat, of black japanned tin; the folding fan trumpet, a tin horn attached to a folding black fan to conceal its use; and the Lorgnette hearing horn, of hardened rubber. The otophone has been used to teach articulation to deaf-mutes, because it carries low tones extremely well. The denti phone conveys sound through the medium of the teeth and is worn at tension in the mouth. The acousticon is a modification of the telephone principle, extremely complex, showing on its surface the battery, earpiece, transmitter and connecting cord. It is the most perfect and most expensive of ear-trumpets. The auris is a modification of the acousticon, simpler and less expensive. Countless other instruments have been developed. In general their use is to be discountenanced and other aids for deafness should be used, such as lip reading, and insist ence on being addressed in clearly enunciated tones.