Next, I spent a lot of time last week experimenting with the Astrolabe Mark I -- enough to discover some serious flaws that I wanted to fix before moving on. The biggest problem being the shape, diameter and length of the center post.
The most obvious flaw was the post's diameter. It was too wide. Wide enough so its shadow was two degrees wide on the scale. I took my first set of sights by taking readings from where I thought the center of the shadow was, but clearly that was just a guess. I then tried to improve the center post by grinding the end into a point. But that had its own problems, illustrated in the video below...
Note to self: always take videos in landscape mode!
Anyway, after grasping the fundamental flaw in the center post, I decided to build a better astrolabe: the Astrolabe Mark II!
The main feature of the Mark II is a short, thin center post, made from a 3-penny nail. The short post means the astrolabe is pointed closer to the sun when the post's sharp point is positioned on the scale.
|Mark II Astrolabe with short, thin center post|
The weight, again, was mounted on the bottom. The top-mount gives the weight more leverage, so it doesn't have to be as heavy.
|Astrolabe is now mounted at the top, rather than the center|
To facilitate this double reading, I found a scale that goes from 0 to 90 degrees on both the right and left sides. That way I can take direct readings on both sides, without having to do any math. With a better astrolabe and Philip's improved technique, I expect much better results this week. If only the sun will cooperate!
Next Up: Mark II Astrolabe Results