The three major methods of heating buildings, based on hot air, hot water, and steam, were all developed in the late 18th and early 19th centuries, largely in Great Britain. At the same time, forced ventilation, based either on the drawing power of heat or on the use of mechanical means like the fan, was also established. The greatest application of the new equipment was made by the engineer David Boswell Reid at the Houses of Parliament starting in 1834. Many problems had to be overcome. Medical doubts about ventilation, the rivalry between architects and engineers, and difficulties in reconciling design with equipment were all attacked, and by the last quarter of the 19th century largely solved. Publications of the last two decades of the century standardized the technology and made it readily available to the architect, engineer, and general public. Use of the new technology made possible many new architectural developments. Prison, theater, greenhouse, and hospital were all largely dependent on central heating and forced ventilation. In other building types new levels of comfort and increased standards of safety were made possible. Perhaps the most profound change was in the conception of the building itself. Buildings could be seen literally in terms of living organisms or machines. Reid even defined architecture as the act of enclosing and servicing an interior atmosphere, a notion not developed until the 20th century.