Chivalry: The Etiquette and History of Hat Tipping
“If a gentleman meets a gentleman, he may salute him by touching his hat without removing it, but if a lady be with either gentleman, both hats must be lifted in salutation. If a gentleman stops to speak to a lady, in the street, he must hold his hat in his hand during the interview, unless she requests him to replace it. With a gentleman friend etiquette does not require this formality.” From Frosts Laws and By-Laws of American Society, 1869
Knights would remove their helmet when entering a building to signify a peaceful position, since a knight could not fight or defend himself without the helmet. Since the removal of his helmet made him vulnerable, it informed others that combat or any type of violence was not his motive. This practice also evolved into the removal of one’s hat when entering a building, when hearing the national anthem and in different situations where they would not be going back out in public immediately. Men would hold their hats in their hand when speaking with a lady but would put it back on when they began to walk together if out in public.