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Figure 4.8. photograph of dams. (by permission of jill ashby, sally bannister, and
ruth pettit.)
second printing of the first edition the footnote was removed, though the en-
try for DAMS could still be found in the index and a citation remained on page
199 to the only publication in which Ashby described this device, the paper
“Statistical Machinery” in the French journal Thalès (Ashby 1951). In the sec-
ond edition, of 1960, both the index entry and the citation also disappeared:
DAMS had been purged from history. Despite the obscurity to which Ashby
was evidently determined to consign it, his journal in the 1950s, especially
from 1950 to 1952, is full of notes on this machine. It would be a fascinating
but terribly demanding project to reconstruct the history of DAMS in its en-
tirety; I will discuss only some salient features.
I opened the topic with Ashby's suggestion that “the making of a synthetic
brain requires now little more than time and labour” (1948, 382), and he evi-
dently meant what he said. DAMS was to be the next step after the homeostat.
Its name was an acronym for dispersive and multistable system. A multistable
system he defined as one made up of many interconnected ultrastable sys-
tems. A dispersive system was one in which different signals might flow down
different pathways (Ashby 1952, 172). This gets us back to the above discus-
sion of times to reach equilibrium. Ashby conceived DAMS as a system in
which the ultrastable components were linked by switches, which, depending
on conditions, would either isolate components from one another or transmit
signals between them. In this way, the assemblage could split into smaller
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