According to The Perfect Gentleman (1860) laughter may be classified thus:
The DIMPLERS: The dimple is practiced to give a grace ot the features, and is frequently made a bait to entangle a gazing lover.
The LAUGHTERS: The laugh "is the common risus of the ancients, and is simply and expansion of the smile, accompanied by a slight cachinnation."
The SMILERS: The smile "expresses our satisfaction in a sort of liberal approbation."
The GRINNERS: The grin, by writers of antiquity, is called the syncrusian and was then, as it is now, made use of to display a beautiful set of teeth.
The HORSE LAUGHERS: The horse laugh is an undue expansion of the laugh, accompanied by a boisterous noise, and is not allowable in polite society.
The Perfect Gentleman also notes that "immoderate laughter is exceedingly unbecoming in a lady"; however, "she may affect the dimple or the smile."
Mary McCarthy (1912-89)