Biology Reference
In-Depth Information
Linkage mechanism
D
G
F
h
H
h
f
f
o
Arms
E
E
A
D
j
Valve
Flywheel
A
Figure 1
A schematic representation of the governor James Watt designed for his
steam engine.
The speed of the flywheel determines how far out the angle arms move by centripetal force.
They are in turn linked to the valve in such a way that when the flywheel is turning too quickly,
the steam supply is reduced, and when it is turning too slowly, the steam supply is increased.
Drawing reproduced from J. Farley (1827),
A treatise on the steam engine: Historical, practical,
and descriptive
, London: Longman, Rees, Orme, Brown, and Green.
oscillations. On consulting the Mexican physiologist Arturo Rosenblueth, they
learned of a similar behavior in human patients with damage to the cerebellum
and recognized the importance of dampening the feedback signal to achieve
reliable control. The limitations they found in negative feedback did not dis-
suade them of its importance; on the contrary, it suggested to them that it was
a fundamental principle of design in biological systems and, they proposed,
in social and engineered systems as well. In a paper published in
Philosophy
of Science
, they argued that negative feedback provided a means of resusci-
tating notions such as purpose and teleology, enabling these concepts to be
applied to both biological and engineered systems without invoking vitalism
(Rosenblueth et al., 1943). Their idea was straightforward and powerful - if
feedback enabled the system to maintain a given temperature, then maintaining
that temperature was that system's goal or telos. Wiener and his collabora-
tors championed the notion of negative feedback as a fundamental principle of
design, and with support from the Macy Foundation, they established a series
of twice-yearly conferences known as the Conference for Circular Causal and
Feedback Mechanisms in Biological and Social Systems. Wiener later coined
