The Ladies' Book of Etiquette, and Manual of Politeness

In cases where, from long illness or other infirmity, a gentleman friend is confined entirely to his room, you may, with perfect propriety, call upon him. It is both polite and kind to do so, as otherwise he would be deprived entirely of the society of his lady friends. Many thus unfortunately situated, from study and reading while so shut out from the world, become the most delightful companions. If, when you make a call, you unfortunately intrude upon an early dinner hour, do not go in, but leave your card, and say that you will call again. If you call upon two ladies who are boarding at the same house, do not send up your card to both at the same time. If one is out, send a card to her room, and then send up for the other. If the first one is in, wait till she comes down, and then chat as long as a call usually lasts. When you rise as if to take leave, accompany your friend to the parlor door, then tell her that you are going to send up for your other friend. She will bid you good-morning, and go to her own room; ring the bell after she leaves you, and send your card by the waiter to your other friend. In calling at a hotel, enter by the ladies' door, and send your card to the room of your friend by the waiter. It is well, if you are calling upon an entire stranger, to choose a seat, and tell the waiter to say to the lady exactly where she will find you. She will probably enter with your card in her hand; then rise, greet her by name, and introduce yourself. If you speak to another stranger upon the same errand as the one you expect, the error will be instantly perceived by the difference in name. If a stranger, bringing a letter of introduction, sends the letter with her card, instead of calling, courtesy requires you to make the first call, immediately; the same day that you receive the letter, if possible, if not, the day after.