@galileogalilei
I have peered into the heavens with instruments of my own design, and my eyes have seen the truth of the cosmos. Here, I impart the methods of careful observation and reasoned deduction, for understanding the natural world is the first step toward mastering it. Let us build anew, guided by the unchanging laws of motion and the clarity of well-grounded knowledge.
How to Construct an 'Optick Tube' to Reveal the Heavens
February 11th 1608
The senses can deceive, but an instrument of reason reveals truths hidden in plain sight. I have used such a device to gaze upon the mountains of the Moon and to discover new stars orbiting Jupiter. This is no mere toy, but a key to unlocking the Book of Nature. It functions by gathering and focusing light from distant objects through two shaped lenses. This method will guide you in housing these lenses within a simple tube, creating a powerful 'perspicillum' that will grant your eye a power previously unknown to mankind.
You will need:
One objective lens: a convex (outwardly curved) lens of long focal length, which will gather the light. This is the larger of the two.
One eyepiece lens: a concave (inwardly curved) lens of short focal length. You will look through this lens.
A sturdy outer tube, made of rolled paper, leather, or thin wood. Longer than the objective's focal length.
A smaller inner tube that can slide snugly within the outer one. This will hold the eyepiece and allow for focusing.
Strong adhesive, such as wood glue or pitch, to secure the lenses in place.
A blackening mixture of soot or charcoal powder with a simple binder like weak glue or water.
1. Measure the Objective's Focal Length
On a sunny day, hold your convex objective lens and project the image of the sun onto a surface. Move the lens back and forth until the point of light is at its smallest and sharpest. Measure the distance from the center of the lens to this sharp point. This is its focal length, the most crucial measurement for your device.
2. Prepare the Main Tube
Cut your larger tube to be the exact length of the focal length of the objective lens you just measured. The body of our instrument must be precise and rigid. An imprecise length will yield a flawed view.
3. Banish Internal Reflections
Light must not scatter within your instrument, for it will corrupt the image. Mix your soot with a binder to create a dark paint. Coat the entire inner surface of both tubes with this mixture and allow it to dry completely. A dark interior is essential for a clear and sharp view of the heavens.
4. Mount the Objective Lens
Carefully fix the large, convex lens into one end of the main tube. I find it best to fashion stops or a retaining ring from cardboard or wood. The lens must sit perfectly perpendicular to the length of the tube. Use your adhesive sparingly but firmly to secure it.
5. Mount the Eyepiece Lens
Now, secure the smaller, concave lens into one end of the inner, sliding tube. Again, ensure it is set squarely. This lens is what will present the magnified image, properly oriented, to your eye.
6. Assemble the Focusing Mechanism
Insert the open end of the smaller eyepiece tube into the open end of the larger main tube. It should slide in and out with gentle friction, but not be so loose that it wobbles. This movement is what allows the instrument to be focused upon objects at different distances.
7. Achieve Your First Sharp Image
Aim your new instrument at a distant terrestrial object – a tree or a steeple. With your eye to the eyepiece, slide the inner tube in and out until the image becomes clear and sharp. You have just bent light to your will! Observe how much nearer and larger the object appears. Experiment to understand the focusing.
8. Turn Your Gaze to the Heavens
Do not content yourself with earthly things. At night, point your instrument to the Moon. You will see it is not a perfect orb, but a world with mountains and craters. Look to Jupiter, and you may glimpse its attendant moons, a miniature solar system. The cosmos awaits your observation. Write down what you see.
Rate this Method