For some reason i missed this one. Wow - that letter is remarkable. It's so out-there that it is either a work of 17th century fiction, or Cornelius was a helluva con-man, OR - he discovered some technology bordering on magic.
Assuming this letter is not a fraud - Cornelius is taking his life into his hands by making such bold promises to the king.
Secondly, I am able to make an instrument, with which it is possible to read letters from a distance of one English mile. I do not doubt that, if Your Majesty wishes to come to my help with the cost of it (as I hope), I can ascertain that it will work so much better that it will be possible to read these letters from around 5, 6 or 7 miles; and one will not even need that the letters be – to put it bluntly - big. With the help of these instruments Your Majesty will be able to see things that are 8 or 10 miles away just as well as if they were in Your Majesty’s own room. My intruments are not similar to vulgar optical glasses, and it is not possible to make copies of them.
This had to get the kings attention: this is a military advantage (pre-telegraph & radio of course). But think of the technical implications: "not similar to vulgar optical glasses". So Drebbel has found a way of precisely focusing light (and possibly other electromagnetic waves) that does not require optic lenses ... fascinating! So he could focus solar radiation in a special way ... what cool things could we do with this?
Maybe this was simply solar power - assisted by his special focusing device. A sundial is a pretty accurate clock, as long as the sun shines. By focusing light that arrives from a specific range of angles, we could get a powerful energy source at precisely timed intervals. Maybe he knew how to use steam? Maybe he knew how to make a radiometer? Imagine an expansion vessel or radiometer that was supplied by focused sunlight that was collected over a wide effective surface area due to Drebbels special light collector ... I can imagine a powerful little engine that could start up when the sun reaches a certain point, aka time.
If his collector works with other electromagnetic waves (and he didn't have to know about these other invisible waves in order to make use of them), then possibly he found that his solar device actually worked night and day? I understand there is a new generation of solar panels that work at night, because they absorb other wavelengths that are not blocked by the earth the way that light is blocked. Listen to a shortwave radio - it gets really noisy at night!
But i'm almost certain that he is also talking about tidal power (gravity oscillations) too. We all know that the sea rises and falls twice daily - and any body of water connected to the sea. There is nothing stopping us using tidal power for real energy applications. Maybe he just ran a long tube to a river or the sea? The daily oscillations could certainly power a clock or a display such as described.
But the gravity oscillations that cause the sea tides to rise & fall don't just exist over the sea! They exist everywhere - over land. There are land tides and air tides as well. We just don't see the air rising and falling - but we experience the winds that result from this (as well as the solar energy input into the wind flow). And we don't see the earth rising and falling, because we are standing on it. But rise and fall it does. Not as freely as the air or the water, because of the nature of solids. But tidal energy is immense - and there probably is a way to capture this energy over land, without requiring a connection to the sea. Maybe he was just using barometric pressure (air tides coupled with solar activity).
I wonder if we could make solids behave more like liquids - for the purpose of obtaining tidal power over land? Imagine we elevated a large quantity of solid mass at "low tide" when gravity was weak, and then let them fall onto a gravity wheel at "high tide" when gravity is stronger .... would the energy obtained be greater than the energy expended? If not - why not? Because we know that sea tides can generate enormous energy. Why is the sea different? The attraction between the Moon and the molecules of water in the sea should be exactly the same as the attraction between the Moon and molecules of mass over land ... why do we insist that this is impossible?? I expect some knee-jerk reaction from the armchair scientists who have been trained to drool on demand ... but this is a serious question that needs more than a knee-jerk response.
