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Grinding Glass -Grit

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Grit is a kind of abrasive powder which when rubbed against a material grinds it down. It comes in various sizes and degrees of fineness, usually expressed in the form of mesh size. Mesh size means how many lines of sieve per inch it could pass through. For e.g.- a mesh size of 9 means there are 9 openings per linear inch in the sieve. The size of each opening is determined by the number of openings per inch and the thickness of the wires. If I made a grid it would pass through a sieve with holes of size 9 microns. Also every grit is associated with a number; a 200 grit means if I took a sieve with 200 holes in one inch the grit would pass through. They basically tell us about fineness of the grit. For glass grinding we will first use large, less fine grits (80,120 etc.) to do rough grinding and get the required shape. After which we will use finer grits to polish the surface. Usually grit is seen on sandpapers and grinders, however for our purpose we need powdered grit for flexibi...
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Disassembling a home-made Refractor Telescope

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1. Optical Tube A 680-690 mm PVC pipe, 48mm wide completely painted black was used as the optical tube. Fig. 1 The Tube 2. The Clamp The clamp was custom made with threads at bottom to screw it on to the tripod. Fig. 2 The Clamp 3. Objective Lens It is an achromatic convex lens (uses clever methods to avoid chromatic aberration) with aperture 50 mm and focal length 700mm. It uses combination of crown glass and flint glass to get rid of chromatic aberration. Fig. 3 a) The Lens b) Visible Boundary of crown and flint glass 4. Lens Housing The objective lens is placed in a bucket like holder which holds it in front of the optical tube. Fig. 4 The Housing a) Side View  b) Top View 5.   Diagonal It is a mirror at an angle of 45 degrees that reflects light from the objective by 90 degrees. By redirecting optical path to the side of the telescope, the diagonal mirror allows for more comfortable viewing. Without it, the observer would need to position themselves awkwardly, often a...
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Refractor Telescope : Build Yourself

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REFRACTOR TELESCOPE A refractor telescope, also known as a dioptric telescope, is a type of optical telescope that uses a lens as its primary focusing mechanism. Invented in the early 17th century by Hans Lippershey, and later improved by Galileo Galilei, refractor telescopes have played a crucial role in the development of astronomy. This article will explain the working principles of a refractor telescope, its components, and its applications. Basic Principles of Refraction To understand how a refractor telescope works, it is essential to grasp the basic principles of refraction. Refraction is the bending of light as it passes from one medium to another with different densities. This bending occurs because light travels at different speeds in different materials. When light enters a denser medium, it slows down and bends toward the normal line (an imaginary line perpendicular to the surface of the medium). Conversely, when light exits a denser medium into a less dense one, it speeds ...
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The Different Names of Moon: A Historical Standpoint

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The most beautiful sight to look at in the night sky is the full moon. Moon reaches its full moon state approximately every 14 days. Now we are quite aware that in the ancient times, when science was not quite developed, common population had resolved to various ways of understanding natural phenomena coupled with various naming methods. The full moons we see around the year are no exception. People  tend to name things on the basis of phenomena to which they are linked  with, so as for the common people to have a better, easier way of understanding. Like Lymphatic Filariasis, which is a disease, they would say elephants feet because of how the limb swells up. Today we will be talking about how people gave the same moon names  just because the time when the full moon occurred coincided with  some phenomenon. Now, naming of the moons varies from tribe to tribe, depending on what calendar system they followed. Here I am going to discuss the names that were commonly us...
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