Whist
Signalling between partners by means of the card-play was well understood and used. Examples are: leading the top card in a sequence, such as K from KQJx, and also leading 4th highest from any suit (which implies you hold one or two top honours in that suit). In 1834 Lord Henry Bentinck invented the "high-low" signal, which encourages partner to continue the suit. Some advanced ideas were known. Alexandre Deschapelles (17801847), a French genius at both cards and chess, invented a play now known as the Deschapelles coup. It is the sacrifice of a high-ranking card to get entry to partner's hand.