Corpora: rotagraph

[Pieter de Haan]

Dear all,
One of my literary colleagues has recently come across the term "rotagraph"
in an early 20th century letter. The term was used by an author who writes
that he has received a rotagraph of the first 50 pages of his intended book
from Oxford University Press. Apparently te term refers to a technique or
procedure which was new at the time. The term does not occur in the OED.

Does anybody know the term?
Could this term have referred to (the equivalent of) proof pages?

All the best,
Pieter
. . . . . . . . .       Dr Pieter de Haan
.           _+_ .       Department of English
. . . . . .(***).       University of Nijmegen
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