Theatres were built in several of the larger cities, and noted singers began to appear from abroad. The first of these appears to have been Miss Broadhurst, who appeared in Philadelphia in 1793, at the Chestnut Street Theatre. She was closely followed by Mrs. Oldmixon. 1750. April 30. "The Mock Doctor," and Dec. 3, "The Beggar's Opera," given at the "Theatre in Nassau St.," New York City. The first performances of ballad opera on record in that city. 1750. A Collegium Musicum was established about this time at Bethlehem, Pa. 1752. Sept. 14. First record of an orchestra being employed, at a performance of "The Beggar's Opera" at Upper Marlborough, Md. 1753. Sept. 13. The first theatre (built for the purpose) in New York City, erected in August and opened in September with "The Conscious Lovers" followed by the ballad farce, "Damon and Phillida," given by Lewis Hallam's company. 1754. First concert hall in Boston opened by Gilbert Deblois, at the corner of Hanover and Courts Sts. 1756. Mar. 16. New organ built by Gilbert Ash, dedicated at the City Hall, New York City, when an organ-concerto by G. A. Hasse was played. In the same year a new organ was placed in King's Chapel, Boston, replacing the Brattle organ. 1756. The first mention of French horns in America made by Benjamin Franklin, writing of the fine music in the church at Bethlehem, Pa., where flutes, oboes, French horns, and trumpets were accompanied by the organ. 1757. Dr. Arne's "Masque of Alfred" given in Philadelphia by the students of the College of Philadelphia. 1759. The first known American song, "My Days Have Been so Wondrous Free," composed by Francis Hopkinson. 1759. The first avowedly musical organization in America, "The Orpheus Club," existed in Philadelphia, and was probably founded about this time. 1761. Feb. 3. Concert given by Mr. Dipper, organist of King's Chapel, Boston, in which two French horns were used. First mention of this instrument in New England. 1761. "Urania, or a Choice Collection of Psalm Tunes, Anthems, and Hymns, from the most approved Authors," published in Philadelphia, by James Lyon, A.B. 1762. A St. Cecilia Society (which lasted for one hundred and fifty years) formed in Charleston, S. C. 1765. A concert of "Musical Glasses" given in Philadelphia. 1765. June 3. The New York _Mercury_ announced a series of summer concerts (open air) to be given at Ranelagh Gardens. These concerts were continued for four years. 1769. First American spinet made by John Harris, in Boston. 1770. Jan. 9. Handel's "Messiah" performed in part (sixteen numbers) at Trinity Church, New York City. 1770. Milton's "Masque of Comus" given by the Hallam Company, in Philadelphia. 1770. "The New England Psalm Singer" published in Boston, by William Billings.