The Chess Player's Chronicle, 1889, printed the following article that appeared in the London edition of the New York Herald. Unless you’re a GM it remains relevant even today:
“Keenest knowledge of chess openings is certainly essential to every chess player who is at all ambitious to make a reputation. It is, however, surprising how little book knowledge apparently is required nowadays by experts of the first rank when engaged in important chess tournaments or set matches. Enthusiastic amateurs who deem it necessary to learn by heart every new variation in the openings frequently burn the midnight oil in industriously analyzing the intricacies of the “Rosenstretter Gambit,” or the combinations which arise from the Meadow Hay opening. They consider it an absolute necessity to digest all the latest chess publications which appear from time to time, from the ponderous and really profound German Handbook down to the shilling pocket chess manual. Such enthusiasts might well pause, and with out recent experience enquire whether such studious labour is not wasted in these days of the modern chess school.”
The Meadow Hay is also known as the Ware Opening and begins 1.a4 and the Rosenstretter Gambit is a variation of the Muzio Gambit and begins 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. d4 g4 5. Bxf4; it’s considered to be refuted, but the similar Quaade Gambit, or as it is sometimes called, the McDonnell Gambit. (1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Nc3 Bg7 5.d4 g4 6.Bxf4 gxf3) in which white sacrifices a piece for unclear compensation isn’t. The only problem with the Quaade is that it has not been thoroughly tested and it remains for white has to prove he has compensation.
There is a good sample of annotated Quaade Gambit games HERE and here’s a sample from Chessbase’s Simon Williams’ DVD, King's Gambit.