![]() ![]() The device, itself fixed, records the apparent motion and intensity of the sun across the sky, burning an image of the sun's motion across the card. ![]() This effect is exploited in the Campbell–Stokes recorder, a scientific instrument which records the brightness of sunlight by burning the surface of a paper card bent around the sphere. Since a crystal ball has no edges like a conventional lens, the image-forming properties are omnidirectional (independent of the direction being imaged). ![]() ![]() The refractive index of typical materials used for crystal balls ( quartz: n = 1.46 window glass: n = 1.52 ), focus infinity to a point just outside the surface of the sphere, on the side of the ball diametrically opposite to where the rays entered. Ball lenses have extremely high optical aberration, including large amounts of coma and field curvature compared to conventional lenses. The same optical laws may be applied to analyze its imaging characteristics as for other lenses.Īs a lens, a transparent sphere of any material with refractive index ( n ) greater than air ( n = 1.00 ) bends rays of light to a focal point for most glassy materials the focal point is only slightly beyond the surface of the ball. In particular, a ball lens (or "lensball") is a bi-convex spherical lens with the same radius of curvature on both sides, and diameter equal to twice the radius of curvature. Art of scrying Ī crystal ball is an optical lens. Fortune tellers, known as drabardi, traditionally use crystal balls as well as cards to seek knowledge about future events. The use of crystal balls for divination also has a long history with the Romani people. Immediately before the appearance of a vision, the ball was said to mist up from within. Ĭrystal gazing was a popular pastime in the Victorian era, and was claimed to work best when the Sun is at its northernmost declination. He devoted much of his life to alchemy, divination, and Hermetic philosophy, of which the use of crystal balls was often included. John Dee was a noted British mathematician, astronomer, astrologer, geographer, and consultant to Queen Elizabeth I. By the fifth century CE, scrying was widespread within the Roman Empire and was condemned by the early medieval Christian Church as heretical. In the first century CE, Pliny the Elder describes use of crystal balls by soothsayers ( "crystallum orbis"). In more recent times, the crystal ball has been used for creative photography with the term lensball commonly used to describe a crystal ball used as a photography prop. It is generally associated with the performance of clairvoyance and scrying in particular. Keeping the image intact can be accomplished by locating the crystal ball in such a way that your guests are most likely to stay directly in front of the globe.The Crystal Ball by John William Waterhouse (1902)Ī crystal ball is a crystal or glass ball and common fortune-telling object. Because the image is being reflected from below it is best viewed directly from the front, as deviation from head-on will tend to cut off the image. I used an iPad2 as my video device, but any video display that fills the opening in the bottom of the globe will do. I used ‘Vloop’ App, but there are several out there. The video is run in a looping program so that it continuously repeats so there is no need to access the video device to start or stop the content. You can also record your own video and personalize the content. However the one I am using, and like the best, is found on our own Instructable’s website from a previous Instructable. Many versions of Madame Leota can be found on YouTube. I used video of her face for the image in the crystal ball. Madame Leota is the medium in Disney’s Haunted Mansion attraction that appears in the séance room’s crystal ball casting spells. That’s it! I hid my video source in a cardboard box suspended by black fine steel wires. The Madame Leota visual effect is simple take a acrylic globe add a video display under it and then place a sheet of clear plastic in the globe at a 45 degree angle to reflect the image forward. I had fun putting this display together and you probably will too. My version included Madame Leota in her crystal ball floating in the air above the séance table. Inspired by Madame Leota in Disney's Haunted Mansion attraction, I thought I would try to create a séance scene. ![]()
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