I've just acquired a copy of what Peter Daniels described as "the
first book on writing from a scientific perspective":

Taylor, Isaac. 1883. The alphabet: an account of the origin and
development of letters. Vol. 1: Semitic alphabets; Vol. 2: Aryan
alphabets. London: Kegan Paul.

756 pages of delight! Some very nice charts of Brahmic scripts in
Vol. 2. In due course I expect that I will scan in useful bits if it
will help us to encode new scripts.
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Michael Everson *** Everson Typography *** http://www.evertype.com