Chimney

A chimney is a structure which provides ventilation for hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney, effect. The space inside a chimney is called a flue. Chimneys may be found in buildings, steam locomotives and ships. In the United States, the term smokestack (colloquially, stack) is also used when referring to locomotive chimneys or ship chimneys, and the term funnel can also be used.

The height of a chimney influences its ability to transfer flue gases to the external environment via stack effect. Additionally, the dispersion of pollutants at higher altitudes can reduce their impact on the immediate surroundings. In the case of chemically aggressive output, a sufficiently tall chimney can allow for partial or complete self-neutralization of airborne chemicals before they reach ground level. The dispersion of pollutants over a greater area can reduce their concentrations and facilitate compliance with regulatory limits.

Chimneys (play)

Chimneys is a play by crime writer Agatha Christie and is based upon her own 1925 novel The Secret of Chimneys. The play was written in 1931 and was due to open at the Embassy Theatre in Swiss Cottage in December of that year. One year previously, Black Coffee, Christie's first performed stage play, had opened at the same theatre.

As was the law at the time, the play was vetted by the Lord Chamberlain's Office and passed for performance. Several press articles referred to the new play but suddenly, and without explanation, the theatre substituted Mary Broome, a four-act comedy from 1912 by Allan Monkhouse, in its place.

The play was all-but-forgotten until December 2001 when John Paul Fischbach, the artistic director of the Vertigo Mystery Theatre in Calgary, Canada was looking to re-launch the company after it had been forced to vacate its home in the Calgary Science Centre and was opening in its new home of the Vertigo Theatre Centre. In looking for something special and relatively unknown to celebrate the opening, Fischbach contacted Agatha Christie Limited, who handle the author's rights, and was told by its chairman (and Christie's grandson, Mathew Prichard) that the only relatively unknown stage work that could be performed was the 1930s play A Daughter's a Daughter which was performed once in the 1950s but had previously been revised into a 1952 novel published under the nom-de-plume of Mary Westmacott.