- A method of changing wings or flats thatmade use of wooden channels along which the pieces could slide. Thesystem was introduced by Inigo Jones in his court masques and remainedin use in the British theater until the mid-19th century. The groovessystem had the disadvantage of being noisy, however, and occasionallya flat would stick in the channel. The end of the system washastened by the installation of the Continental carriage-and-frame systemat Covent Garden. Irving removed the last remaining grooves in London fromthe Lyceum Theatre in 1880.