Thanks for your message. Apologies for not getting back to you sooner.
For a while I was experiencing technical problems and then, since I am
in the UK, it was my night-time.
First, this is the passage you want:
"Although some of the Persians were distant a thirty days' journey,
they all received the order on that very day, thanks to the skilful
arrangement of the posts of the guard, a matter that it is not well to
pass over in silence. Persia is cut by many narrow valleys and has
many lookout posts that are high and close together, on which those of
the inhabitants who had the loudest voices had been stationed. Since
these posts were separated from each other by the distance at which a
man's voice can be heard, those who received the order passed it on in
the same way to the next, and then these in turn to others until the
message had been delivered at the border of the satrapy."
From Diodorus Siculus - [Library of ]World History 19.17.5-6
The numbers are a standard way of citing from Diodorus. In this case,
it is Book 19 of his "Library of History", Chapter 17, paragraphs 5
The article at livius.org is by a classical scholar, so the citation
should be reliable, although he doesn't actually specify which
translation he is using. The book and chapter are confirmed elsewhere.
There is an English translation of Diodorus Siculus by C. Bradford
Welles, published by the Loeb Classical Library, part of Harvard
University Press. It is on sale at Amazon:
There is another translation by Russel M. Geer, also published by
Loeb/HUP, which is listed by Barnes and Noble:
It is also on sale here:
This is the key information you need, I hope, but you are welcome to
ask for clarification if you have any queries. Below I have given some
additional links which may also be useful.
Thank you for drawing my attention to such an interesting area of
history. Good luck with your book!
Best wishes - Leli
The passage about the "shouters" is also given here:
Watchmen and Stentors
The author offers this footnote which confirms the other citation -
except for saying 7 instead of 5-6 for the paragraph!:
"Diodorus Siculus, Diodorus of Sicily, Book XIX, 17.7. The passage can
also be found in Aschoff 1984, and in Hennig 1906"
More information on Diodorus
About Jona Lendering
Satraps and satrapies
Out of many searches I found these two the most helpful:
"Darius the Great"
site:livius.org diodorus voice