REDOUBLING
Although the score may sometimes warrant a redouble without extraordinary strength, a redouble practically avows the ability to take six, and probably, seven tricks. In estimating your hand consider the possibility of finding all the remaining trumps in one hand, and do not value honours in the side suits too highly, for if he holds great trump strength the maker is probably short in the other suits. A redouble at “no-trump” indicates protection in every suit.
The dealer should often redouble, not so much on the strength of his hand, but to the score; knowing that should the adversaries win the odd trick the game is lost, and that his redouble will equalise the situation and make it possible for the odd trick to win the game for either side.