National Geographic : 1984 Jul
Members Forum Hologram Cover Lost my balance and fell into your March 1984 cover. Might have been seriously injured. Fortunately, the eagle was dozing! Robert L. Kocher Thousand Oaks, California Beautiful and fascinating-but I may never get beyond the cover. Roy Trelease Norwalk, Connecticut Superb, absolutely superb. Natalie Parkison Brighton, Colorado Few readers, I suspect, experienced my thrill of seeing a bold 3-D image of the eagle. Full depth perception was something I haven't had since an aviation accident 36 years ago deprived me of the sight of my right eye. I don't pretend to under stand the mechanism by which one eye can per ceive a three-dimensional image from a flat hologram, but it certainly works. Perhaps one day books will be illustrated with such images, to the delight of readers with single vision as well as those with normal sight. Frank B. Brady Annapolis, Maryland I wonder how many others automatically looked on the other side of the marvelous hologram cov er to see what was behind it! Elizabeth R. Goree Prairie du Chien, Wisconsin We do know of one reader who tried to scrape away thefoil to find a prizewinningnumber. You state that the hologram on the cover is the first such to be published by a "major magazine." My memory suggests that many years ago, before its demise, Look magazine published a holo gram. Charles O. Houston Kalamazoo, Michigan The 3-D picture you refer to was a stereoscopic color photograph covered by lenticular plastic. It was not a hologram. Why is it that when viewed upside down, the im age reverses itself: The wings of the eagle come forward, and the body takes on the appearance of a mold? Frank O. Shaw Seattle, Washington You have discovered that our hologram has two personalities. Turning the eagle upside down produces a new set of light waves, and each eye now sees what the other did before, reversing depth perception and making the eagle's wings bulge outward and its chest inward. Lasers The March issue's feature on the laser was excel lent! The article, however, did not mention the "cold laser" now being utilized by physical thera pists. This helium/neon laser provides clinicians with a method of enhancing healing of open wounds. In addition, this brilliant red beam has been shown to serve as an analgesic when target ed at acupuncture and trigger points on the skin. Currently under clinical investigation, the cold laser promises to be a valuable adjunct to physi cal therapists and colleagues in allied health professions. Joseph Kahn State University of New York Stony Brook, New York Rhinos I was very interested in the article on the killing of rhinos (March 1984). I detest seeing these mag nificent beasts killed just for their horns. Is it pos sible that rangers and game management personnel could dart-tranquilize many of the rhi nos and remove the horns? They could bandage the wound, give appropriate antibiotics-if needed-and release the animal. Since the horn grows back, the rhino would not be permanently disfigured, but its value to poachers would be greatly reduced. Clay Lasiter Harlingen, Texas This idea has been suggested by a number of our readers. However, besides the prohibitive ex pense offinding, darting,and dehorningthe rhi nos at repeated intervals, hornless rhino cows might be less able to defend theircalves. A "white" rhino indeed! The color is little differ ent on either the white or black. Not white, but the Dutch word weit, referring to the upper lip. It was misunderstood for white, and the misnomer stuck. It is really the wide rhino. Bob Aungst Edina, Minnesota The name does derivefrom the wide squaresnout and not the skin color, which takes on the hue of the soil in which the rhino wallows. Ceratother ium simum is now officially known as the square lipped or white rhinoceros, also Witrenoster.