You want to read this book:

Shaping the Day: A History of Timekeeping in England and Wales 
1300-1800, by Paul Glennie and Nigel Thrift

It has a rather large section on the verge and foiliot designs, and a 
number of very good sources.


On 8/1/2013 12:58 AM, Jerry Harder wrote:
> I have been doing some research on clock escapements.  Turns out 
> pendulum escapements aren't period by about 65 years.  Verge and 
> foliot with a crown wheel where the pallets engage with opposite sides 
> of the crown wheel are.  There are some verge and foiliot escapement 
> designs which have 2 gears with pins that replace the crown wheel and 
> the pallets both engage the top of these two pin gears.  I am looking 
> to prove or disprove weather this type is also period.  Any help would 
> be appreciated.  A simple search on firefox gives a great overview on 
> wickipedia, and shows the two 
> pin-wheeled type.?