<html>
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 11 (filtered)">
<style>
<!--
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:#606420;
text-decoration:underline;}
span.EmailStyle17
{font-family:Arial;
color:windowtext;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.25in 1.0in 1.25in;}
div.Section1
{page:Section1;}
-->
</style>
</head>
<body lang=EN-US link=blue vlink="#606420">
<div class=Section1>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>There was a question about what kind of accuracy would be
required. Well, the more the better. Without electronic assistance
this was done by letting the clock run for a day and measuring it against a
known good time source, adjusting the pendulum, repeat. Running the clock
for longer periods between measurements obviously makes the adjustment more
accurate.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>With electronic assistance the same rules apply. Running
the clock longer between measurements makes the adjustment more accurate.
Let’s do some math. Assuming we use one pendulum swing to measure
the period and say that this clock is geared for a one second pendulum cycle. If
we can measure that one second with an accuracy of 100ths of a second, then our
average error will be half that or</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>0.005 sec / sec or</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>0.3 sec / min or</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>0.3 min / hr or</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>7.2 min / day or</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>216 minutes over 30 days</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>If this is a 31 day clock, over 3 hours off is not very good
per winding. If I can get millisecond accuracy, then I’m down to
21.6 minutes over 30 days which is still not very good. Now if I increase
my sample size to 10 pendulum cycles and still maintain millisecond accuracy, I
can set the clock within 2.16 minutes lost/gained in 30 days. That would
be a good start. It would only take me 10 seconds to decide to adjust the
clock slower or faster and I would eventually be correct to within .072 minutes
per day when I finished adjusting to the accuracy level of this instrument.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Further adjustments using longer sample times would then be
able to increase the accuracy to the desired level or at least to whatever
level of accuracy the clock works are capable of.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
</div>
</body>
</html>