The hat of the famous Sir Arthur Conan Doyle’s character is also known as a "deerstalker hat". It can be safely said that it appeared in the last third of the 19th century.
It was used as a headwear for walking in the woods or in the countryside, as well as for hunting, for it is very practical and convenient. Its visors protected the face and the neck from the sun, the rain, and the wind, and the earflaps could be tied under one’s chin for extra warmth.
It fits both men and women.