A gyroscope is any rotating body that exhibits two properties: gyroscopic inertia or rigidity in space and precession or the tilting of the axis at right angles to any force tending to alter the plane of rotation. These properties are inherent in all rotating bodies, including the Earth. The term gyroscope is applied to spherical, wheel-shaped or disk-shaped bodies universally …

A straight line drawn between two places on a world map looks like the shortest distance between them. But this usually isn’t so, because most maps are distorted. Take a look at a globe. If you stretch a piece of string over the globe, joining Japan and Denmark, you will see that the shortest route runs over the North Pole, …

Gluten is a protein found in wheat, rye and barley. In some genetically predisposed children, food containing gluten causes small-bowl mucusal damage resulting in a disease called gluten-sensitive enteropathy or celiac disease. The treatment is a strict gluten-free diet i.e. elimination of wheat, rye and barley products from the diet. Gluten-free foods are commercially available.

A flipbook is a small book with a series of printed images that create the illusion of motion when its pages are rapidly flipped. Typically, a flipbook is held in one hand while the thumb of the other flicks the pages and the user concentrates on the middle of each page. The flipbook relies on a basic optical principle known …

It is a type of wide-angle lens used in photography to capture extremely wide and hemispherical images. Its focus length varies between 8-10 mm for circular lenses and 15-16 mm for full frame lens. Originally developed for use in meteorology and astronomy, it is used in planetariums and dome theatres to show pictures on a broad canvas.

In Rail Terminology: A fishplate, splice bar or joint bar is a metal bar that is bolted to the ends of two rails to join them together in a track. The name is derived from fish, a wooden bar with a curved profile used to strengthen a ship’s mast. The top and bottom edges are tapered inwards so the device …

False vacuum and true vacuum form a metastable system. Metastable state is a state which does not change with time but is susceptible to falling into lower-energy states with only slight interaction. It is analogous to being at the bottom of a small valley when there is a deeper valley close by. True vacuum is the name applied to a …

It is an expanding bullet designed to grow on impact, increasing in diameter to limit penetration and/or produce a larger diameter wound. There are many expanding bullet designs though the most commonly encountered are hollow-point bullet and the soft-point bullet. Such bullets are sometimes known as ‘dum dum’ bullets. After an early British example produced in the Dum Dum arsenal, …

A dowser is another name for a water-diviner someone who can tell where there is water lying underground. The dowser uses a whole variety of tools to find the water, but one of the most common is the Y-shaped twig from a hazel tree. The dowser holds the twig by the two prongs of the Y, with the long stem …

There are about 500 active volcanoes around the world, not including those hidden by the sea. A few, such as Stromboli, a volcanic island off the north-eastern coast of Sicily, are active nearly all the time. But most undergo long periods when they are dormant, or sleeping. Some volcanoes stay dormant for so long that they are thought to be …