ВУЗ:
Составители:
Рубрика:
114
The general problem of maintaining comfortable conditions in an occu-
pied room has been the subject of study for many years. Early investigators be-
lieved the atmosphere of a crowded room to cause discomfort through its effect
on the lungs, and carbon dioxide, being the principal product of respiration,
was looked upon as the harmful element. Air-conditioning, or ventilation,
as it was formerly called, was therefore considered for many years to be a prob-
lem of supplying sufficient fresh air to dilute the carbon dioxide content.
Experiments led engineers to give up this theory. Severn I men were
placed in an airtight chamber until the carbon dioxide content increased and the
oxygen content decreased considerably. They suffered great discomfort; but
when the air was set in motion by fans, the discomfort at once disappeared.
Other men outside the chamber experienced no discomfort from breathing the
air from the chamber through tubes, but those within the chamber experienced
no relief from breathing outside air. This experiment demonstrated the concept
of air-conditioning, namely, that the cooling effect of the atmosphere upon the
skin is of great importance and that comfort depends upon maintaining the
proper thermal environment. The men within the test chamber were uncomfort-
able because their body heat was not being properly removed, and they became
more comfortable as the fans increased the rate of heat removal.
From the History of Sewerage
Man's sewerage practice has been known from ancient times.
Explorations revealed sewers in Babylon dating from the 7th century
before our era. Considerable information is available about the sew-
ers of Jerusalem, works of this class in ancient Greek cities are
fairly well known and the great underground drains of Rome have
repeatedly been described.
The history of the progress of sanitation in London probably af-
fords a typical picture of what took place quite generally about the
middle of the 19th century in the largest cities of Great Britain and
the United States. Well into the19th century while London outgrew the
narrow limits of the city proper and its adjacent parishes and became a great
metropolis, the centre of the world's commerce, sanitation was as little consid-
ered as magnetism or the use of steam for power purposes.
Страницы
- « первая
- ‹ предыдущая
- …
- 112
- 113
- 114
- 115
- 116
- …
- следующая ›
- последняя »
