The following is an excerpt from “The Gentlemen’s Book of Etiquette, and Manual of Politeness” by Cecil B. Hartley, published by Locke & Bubier in 1875. OF all the amusements open for young people, none is more delightful and more popular than dancing. Lord Chesterfield, in his letters to his son, says: “Dancing is, in itself, a very trifling…