Oh, and for the record, the non radial pin design has the distinct disadvantage of requiring an ODD number of gear teeth in the crown to function. That was their hold up as well. How do you use a compass to construct an odd number of evenly spaced teeth around the circumference of a circle?  It's not just the period manufacturing tools that restrict, but the period design tools as well.


On Aug 1, 2013, at 4:25 AM, Jerry Harder <[log in to unmask]> wrote:

SOOO....   Having reached a dead end and posted to the net I then found the word 'strob'  That opened up everything and I found the sources you mentioned and of course have figured out that both forms of the verge and foliot  design are period, and both appropriate to be hanging around in the great machine with the crown wheel version being the most appropriate (later version) but the double pinwheel ie strob version being easier to build (out of wood at least). But when did I ever take the easy way out. 

So which one do you have half built?  You are ahead of me on this, right?

On 8/1/2013 2:58 AM, john heitman wrote:
[log in to unmask]" type="cite">
not only is that type period, it is recognized as frontrunner for the first truly mechanical only movement.

The man who was to be come Pope Sylvester II had what is acknowledged as the first completely mechanical clock in 996 CE, and it supposedly had this radial pin design.  But that is all buried in my notes as to the quote source.

However, to give you the reference you are desperately seeking:

1327 CE - Richard of Wallingford ("Tractus Horologii Astonomici") wrote on a tower clock he built for the Abbey St. Albans that it had a "strobe escapement", two wheels on the same axle with alternating radial teeth/ verge suspended BETWEEN them, with a short cross piece oscillating as the wheels rotated past. (no currently known period examples exist, primarily because they lost as much as several hours a day, and were quickly changed over in the 1600s to the vertical pendulum because those lose only minutes a day.

Part of the problem is that a) the first treatise on clock making wasn't until 1364 when the son of a clockmaker expounded upon his father's work, and b) as stated above, they were all changed over to the vertical pendulum in the 1600s.

So,Good Master, since I seem to have gotten you hooked,  your other research terms should include "escapements" and, oddly, "engines".

The best site I found, however, was  Full out presentation on the subject. I can give you more if you like, but that is the mother lode.


On Thu, Aug 1, 2013 at 1:41 AM, Miklos.Farma <[log in to unmask]> wrote:
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.