Next message: Henry C. Halboth: "Re: Azimuth and Declination formulae"
The old navigation manuals suggested checking the log line and half minute
glass occasionally. One way to check the glass was by pendulum. As I recall, the
length of the pendulum, to the center of the musket ball that formed the
weight, was sometimes given as 29 and 1/4 inches, and sometimes as 29 and 1/8.
Count a second each time the pendulum passed the bottom. I suppose you had to
give the pendulum a few moments to settle the length of its swing.
Bruce
