hieroglyphs, engraved to a depth of several inches and carefully polished. The hieroglyphs are inscribed in vertical columns, which are read from the top downward; and in each case the middle column is in honor of Thothmes, by whom the obelisks were first erected, and the side columns in honor of Rameses II. CLEPSYDRA, klěp-si'dra, or WATERCLOCK, an instrument for the measurement of time by the escape of water from a vessel through an orifice. Its origin is extremely ancient, and has generally been attributed to the Egyptians. Two descriptions of clepsydræ have been employed - one in which the water merely escapes through the orifice, the other in which the same level is constantly maintained by the introduction of a fresh supply of water, and a uniformity of efflux secured by retaining throughout an equal amount of pressure on the fluid as it issues from the bottom of the vessel. In one kind of water-clock the measure of time is registered on a dial-plate by means of a hydraulic apparatus acted on by the efflux of water from a cistern. The simpler form was used in Athenian courts where a speaker was allowed so much water for his speech, according to the importance of his case. The more complicated form is said to have been invented by Plato; or by Ctesibius, according to some. Both forms were introduced into Rome in 159 B.C. These instruments are now scarcely ever constructed. CLERC, Laurent, klar, French deaf mute: b. La Balme, Isère, France, 26 Dec. 1785; d. Hartford, Conn., 18 July 1869. At the age of 12 years his uncle took him to Paris, and placed him in the institution for the deaf and dumb. He became the favorite pupil of the Abbé Sicard. His intellectual condition, like that of most of the uninstructed deaf mutes, was at this time deplorable. “I had,” he says, "a mind, but it did not think; I had a heart, but it did not feel. My mother had endeavored to show me the heavens, and make me know God, but her attempts were vain; I could comprehend nothing. I believed that God was a tall, big, and strong man, and that Jesus Christ, having come to kill us, had been killed by us, and placed on a cross as one of our triumphs." Under the skilful instruction of the Abbé Sicard he made rapid proficiency, and in 1805, after passing eight years in the institution, he was appointed tutor, and in 1806 a salaried teacher. In 1816 Clerc formed the acquaintance of Gallaudet (q.v.), who persuaded him to accompany him to this country, here to lay the foundation of deaf mute instruction. (See DEAF MUTES). They succeeded in establishing an institution, since known as the American Asylum for the Deaf and Dumb, at Hartford. On 15 April 1817 the asylum was opened with seven pupils, and Messrs. Gallaudet and Clerc installed as teachers. The greater part of the teachers sent to other institutions for the deaf and dumb from this mother asylum received their training at his hands. He married a deaf mute, but his children could both hear and speak. CLERESTORY, or CLEARSTORY, the upper part of the nave in churches, above the triforium where a triforium is present, and formed by walls supported on the arches of the nave, and rising above the roof of the side aisles. In these walls windows are inserted for the purpose of increasing the light in the nave. The earliest known is that of the Hypostle Hall at Karnak. The Romans used the device in their lofty bath halls; the same arrangement is seen in the basilica of Maxentius and in modern halls of the same type, e.g., the Pennsylvania Railway Station in New York. The clerestory was an essential feature of the Christian basilicas; occurs also in Hagia Sophia and the Byzantine churches. In Nor man architecture the three stories of pier arcade, triforium and clerestory are of nearly equal height, but in Gothic the clerestory becomes relatively of greater significance and in late Gothic work is often very lofty. CLERGY (Lat. clericus, from Gk.κλpos, a lot), in the Christian Church, that portion of the faithful which is set apart for the ministry of religion. The separation from the laity became more marked through the multiplication of offices and titles, privileges, rights, peculiar dress and habits. In the Roman Catholic Church there are eight grades or distinctions of clergy, namely, that of the simple cleric, those of the four minor orders and those of the three sacred orders of subdeacon, deacon and priest (qq.v.). The last three are regarded as being of divine institution. The simple cleric is one who has received the ecclesiastical tonsure; by that rite he is made a clerk or cleric, and as such is entitled to certain rights, privileges and immunities and assumes certain obligations not incumbent on the laity. In Protestant churches the distinction between clergy and laity is much less wide. See HOLY ORDERS. CLERK, formerly the name given to an ecclesiastic. Since learning of all kinds at first centred in the Church, the name was assumed by all men of learning, whether belonging to Church or laity. At present the term designates one who has charge of an office or department, subject to a higher authority, as a board, corporation, etc.; a secretary, as _the clerk of the House of Representatives or Senate, clerks of the various courts, etc. In England a parish officer, a layman, whose business used to be to lead the responses in the church services and to perform other duties connected with the parish; a parish clerk. The mediæval use of the terms "clerk in holy orders" and "clerk in minor orders" still exists to distinguish the various ministers of the Established Church. CLERK-MAXWELL, James. See MAX WELL. CLERKE, Agnes Mary, Irish astronomer: b. Skibbereen, Ireland, 10 Feb. 1842; d. London, 20 Jan. 1907. She gave her life to astronomical research, was awarded the Actonian prize and became a member of the British Astronomical Association. She was also honorary member of the Royal Astronomical Society. She published A Popular History of Astronomy in the Nineteenth Century) (1885; rev. ed., 1902); System of the Stars (2d ed., 1905); The Herschels and Modern Astronomy) (1895); 'Problems in Astrophysics (1903); Modern Cosmogonies' (1906); The Concise Knowledge of Astronomy) (with J. E. Gore and A. Fowler, 1898). She contributed to the 'Catholic Encyclopedia,' the 'Dictionary of |