The various resonating pipes used by pipe organs to make music. Most churches have one of these, and the best thing about them is that every one is different, and you can keep yourself awake by counting them while the sermon is droning on.

A popular pattern found in chess problems are organ pipes. An example of a set of organ pipes would be any rank or file which contains both of one side's Rooks sandwiched by both that same side's Bishops. As illustrated below, both white and black have an organ pipe arrangement.

+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    |    |
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    |    |
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    | B  | 
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    | R  | 
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    | R  | 
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    | B  | 
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    |    | 
+----+----+----+----+----+----+----+----+ 
|    |    | b  | r  | r  | b  |    |    |
+----+----+----+----+----+----+----+----+

Organ pipes were first used, intentionally, in a problem authored by Sam Loyd in 1859. While the problem itself well known as a unique problem unto itself, the BRRB chain was borrowed over and over by Pal Banko, Jan Hartong, and Byron Zappas, among others. The first problem which Loyd employed organ pipes was a subtle interference problem, which employs a Grimshaw opportunity against black's position.

Sam Loyd
Organ Pipes, 1859

+----+----+----+----+----+----+----+----+
|    |    | b  | r  | r  | b  |    |    |
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    |    |
+----+----+----+----+----+----+----+----+
| p  |    |    |    |    |    |    |    | 
+----+----+----+----+----+----+----+----+
|    |    |    |    |    |    |    | Q  | 
+----+----+----+----+----+----+----+----+
|    | p  |    | k  | p  | P  | p  |    | 
+----+----+----+----+----+----+----+----+
|    | P  |    | p  | N  |    | K  |    | 
+----+----+----+----+----+----+----+----+
|    |    |    | P  |    |    |    |    | 
+----+----+----+----+----+----+----+----+ 
|    |    |    |    |    |    |    |    |
+----+----+----+----+----+----+----+----+

White to play and mate in two.

qa5

  • 1...Bc5 2. Qa1# The Bishop opens d5 from the threat of 2. Nf5#, but only temporarily as the King can now not escape from the Queen's diagonal mate.
  • 1. ... Bd7 2. Qd5# The Bishop interferes with the dRook preventing 2. Nf5#, but also preventing the capture 2...Rxd5.
  • 1. ... Bd6? 2. Qd5# The Bishop interferes with the dRook, accomplishing nothing while preventing the capture 2...Rxd5.
  • 1. ... Bb7? 2. Nf5# The cBishop wanders from its defense of f5, accomplishing nothing while preventing the capture 2...Bxf5.
  • 1. ... Bf5? 2. Nxf5# The cBishop tries to occupy f5, which walks headlong into the checkmate by the Knight.
  • 1. ... Rd7 2. Nf5# The dRook tries to gain a tempo, but interferes with the cBishop, preventing the capture 2...Bxf5.
  • 1. ... Rd6 2. Nf5# The eRook tries to gain a tempo, but interferes with the cBishop, preventing the capture 2...Bxf5.
  • 1. ... Rd5? 2. Qxd5# The dRook tries to put pressure on the Queen, but it is ill-conceived by moving the checkmate square adjacent to the King.
  • 1. ... Re5? 2. Qxe5# The eRook tries to put pressure on the Queen, but it is ill-conceived by moving the checkmate square adjacent to the King.
  • 1. ... Be7 2. Qe5# The Bishop tries to gain a tempo while keeping the b4 Pawn under its protection, but also interferes with the dRook preventing the capture 2...Rxe5.
  • 1. ... Be6 2. Qe5# The Bishop tries to gain a tempo while keeping the f5 square under its protection, but also interferes with the dRook preventing the capture 2...Rxe5.
  • 1. ... Rd6 2. Qxb4# The dRook tries to gain a tempo while also defending against 2. Qb6#. However it also interferes with the fBishop, preventing the capture 2...Bxb4.
  • 1. ... Re7? 2. Qb6# or 2. Qxb4# The eRook accomplishes nothing, except for introducing many purists' objection to this problem. Each chess problem is intended to have one, and only one, move for white each turn to accomplish the checkmate in the specified number of moves. Given the era during which it was created, I would pressume that the onus was on the problemist to not make a helpmate move for black during the course of their solution. Technically the eRook is interfering with the fBishop, preventing the capture 2...Bxb4 or the interposition 2...Bc5.
  • 1. ... Bg7? 2. Qb6# or 2. Qxb4# This line has the same issues, and consequences, as 1...Re7.
  • 1. ... Bh6? 2. Qb6# or 2. Qxb4# This line has the same issues, and consequences, as 1...Re7.

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