If you've got a science buff on your holiday gift list, you are probably painfully aware of how difficult it is to find the perfect present. Few of us live close to stores that stock a wide selection, and most of what is out there is jammed in a distant corner of the toy section.

But don't despair. Practically anything you can imagine, from techie trinkets to professional gear, is right at your fingertips. With a bit of cyber sleighing, you'll find that the Internet is a virtual mall of gift to warm the hearts of techies, young and old, from amateur to aficionado--and at prices from a few dollars to thousands. In a few clicks of a mouse, you can check out offerings from technical supply houses, museums, professional societies, government agencies and specialized dealers of everything from living butterflies to fossils and scientific antiques. Almost all will accept orders on-line.

Here are a few of the things Scientific American's editors turned up in their annual Yuletide romp on the Web.

Even if you didn't pore over Edmund Scientific's newsprint catalogs crammed with experimental gadgetry in the 1960s, this venerable company is alive and well and offering its fascinating collection of products via the Web. They've got lenses and prisms for just a few dollars and high-quality telescopes and microscopes for several hundred. You can get working solar cells for less than $10 or a range of products powered by them, including the somewhat counterintuitive solar-powered flashlight for $26.95. (Yes, Virginia, it charges during the day--not at night).

Treasure hunters might appreciate a metal detector ($150 to $570), and if you have someone on the list who is never quite sure where they are, Edmund has a good selection of Global Positioning Satellite receivers. For those with a meteorological bent, there is a range of weather stations, barometers and other gear.

For hands-on experimenters, kits and models abound. A good place to start is the Science Kit Center. Sure, there are crystal-growing kits, magic sets and, of course, the traditional chemistry set but they also carry a cadre of specialized chemistry kits that explore everything from food testing to polymers. Those who really get into the environment might appreciate one of the test kits for such things as water quality and safety. A person who needs a companion might find solace in the robot kits, which include programmable models with sensors that react to light and sound.

Even building blocks have gotten a new spin for the computer age. Logiblocs are a system of color-coded electronic building blocks that plug together to create electronic circuits ($61.95). Kids can create all sorts of inventions, from burglar alarms to scanners and zappers--all complete with sound, flashing lights, buttons to press and automatic sequences.

If you know someone who really wants to get close to the soul of the machine, stop by Lynn Computer Products. They will send you all the parts needed to construct a high-end personal computer. You start by selecting the features you want--from CPU to hard drive. Lynn sends a quote within 72 hours and, when the sale is completed, rushes all the pieces--with assembly instructions--to the lucky new owner.

Model builders with an anatomical bent might appreciate one of the kits from the Museum of Science Boston, where $16 will buy a kit to build a >human eye, head or lung. The chemists on the list might be intrigued by the multitude of molecular models--from complex proteins to simple ice crystals--available from Darling Models.

Some truly hair-raising gifts can be found at Science First, which supplies electronics demonstrations to schools. A Van de Graf generator that churns out 200,000 volts and throws arcs four inches goes for $113.95, assembled. (It is recommended for ages 10 and up--the more "up" the better, we think.) Someone might also get a charge out of the "only fully assembled, totally safe 50,000-volt Tesla Coil on today's market" ($205.95) or revel in the power of an electromagnet that will heft 500 pounds with just two "D" cell batteries.

We all know someone who complains that are never at home when great science documentaries air on TV. You can help them out by visiting the Store of Knowledge, the on-line store of the Public Broadcasting System. The extensive collection of videos is clearly indexed by category through pop-up menus. A little looking turns up such classics as NOVA's three-part miniseries In Search of Human Origins ($59.85, three hours on three videotapes) or the recent Mysterious Mummies of China ($19.95, 60 min.).

This year, you can even give someone a tour of the vast collection at the Smithsonian Institution--without the tired feet. A new CD-ROM, The Smithsonian Museum Collection ($24.95), includes 650 interactive attractions from the various museums and the National Zoo. You can control the perspective, zoom in and out, and rotate the object on any axis.

geologists hammer

Naturalists who poke around in the field will appreciate high-quality tools of the trade. If there is a rockhound or fossil hunter on your list, try Kooter's Geology Tools. They've got a nice selection of rock picks starting at $27. Kooter's also supplies pocket transits (starting at $99), high-quality hand lenses and magnifiers (starting at $15) and an assortment of field gear, such as tool belts and leather notebook and compass cases.

To please an avid entomologist, stop by American Biological Supply Co. Their extensive on-line catalogue includes the highest-quality nets--both flying and aquatic--as well as professional collecting kits. Specimens can be proudly displayed in museum-quality hardwood boxes and cases.

The more sedentary entomologists might prefer one of the spectacular butterflies and moths mounted by Bruce Ithier. His World of Insects site offers a wide variety of Lepidoptera at surprisingly low prices. A radiantly iridescent Giant Morpho goes for $30.

Those who like their butterflies fluttering may like the gift of farmed cocoons and eggs from Mike's Magic Moths. Luna and Polyphemus cocoons are $8 each; Cecropia, $10 each. Or you could get them a butterfly feeder ($18) from The Nature Company. It comes with butterfly-attracting nectar that contains the vitamins and trace minerals they need at their reproductive peak.

Armchair rockhounds might be delighted to receive a piece of a meteor from The Meteorite Shop. Their offerings include whole stones as found as well as polished pieces that show off the metallic sheen of nickel-iron meteorites and polished slices that show the interior structure. Many are available for less than $50.

For fans of ancient life, the place to go is the Fossil Company. Their catalogue reads like a chronicle of extinction, from Ammonites to Trilobites. They also have plant, mammal and reptile fossils. Some of the more common ones are as inexpensive as $1; you can get a nice Trilobite for $40.

Homo habilis

If you know someone who still doesn't have a skeleton in their closet, check out Skulls International. The offer a life-size plastic skeleton, like those in doctors' offices. You can take one home for just $349. They also offer a full range of less-pricey human and animal skull replicas, from Homo habilis ($119) to shrews and whales, as well as claws, teeth and talons of numerous species.

Of course, almost anyone can use a good field guide. The extensive list of the National Audubon Society's famous series of field guides--from the classics on birds to fossils, mushrooms, minerals, you name it--can be found on the society's Web site. For beginners, there is also the series of First Field Guides for children. And if you are looking for a good book to give to a birder or naturalist, browse through Audubon's Top 10 book selections.

Someone who dreams of orbiting Earth in the space shuttle might settle for the Space Shuttle Operator's Manual ($17.50) from NASA's SpaceShop at Goddard Space Flight Center. It contains detailed description of the shuttle systems and control panels with operating procedures. Other NASA memorabilia include patches ($5.50), T-shirts ($14.95), running shorts ($16.95) and sweatshirts ($28.95). And for the gourmet on your list--a space food, freeze-dried dinner of chicken and rice, peas and instant chocolate pudding ($7.00). (Additional space gifts can be found at the Trading Post at Johnson Space Center.)

Anyone with more than a passing interest in physics will be fascinated by the Century in Physics Timeline, which was prepared to commemorate the centennial of the American Physical Society. This panoramic wall poster was offered to educators and APS members but is also available now to anyone with $35. For ease in sifting through its hundreds of discoveries, it is divided into five color-coded bands that stretch from end to end, divided by scale from the astronomical to the infinitesimal.

This season also offers a rare opportunity to give someone a collection of original time-stopping photographs taken by MIT's famous Harold "Doc" Edgerton, the inventor of stroboscopic photography. The MIT Museum Shop has just 11 boxed sets containing three of Edgerton's most remarkable photographs: Swirls and Eddies of Jack Summers (1938), Bobby Jones' Driver (1938), and Back Dive (c. 1954). The 11-inch-by-14-inch black-and-white prints are signed by Edgerton and presented in a cadet-blue archival folio lined with acid-free paper ($900). If the price is above your budget, the museum also has copies of Edgerton's book, Stopping Time. It contains 22 color and 116 duotones of famous Edgerton photos, such as the bullet bursting through an apple--and it goes for a mere $48.

Plasma lamp


Puzzle solvers can butt their brains against the Architectural Fantasy Puzzle. It consists of 540 pieces printed on clear plastic, allowing parts of underlying images to show through. Solve three separate puzzles, each depicting some of the world's most famous buildings, then layer them to create a striking 3-D image ($22). Others may wish to test their acumen on the 52 crossword, acrostic and 3-D puzzles in the Crossword Puzzle Book ($9) for Scientists and Engineers. Sample: "62 Down (3 Letters): TV Frequency Range. Answer: UHF."

Then there is always that person who won't part with their beloved lava lamp. You might try to bribe them with a Plasma Lamp ($145) from the Exploratorium Store. With the room lights on, the glowing tube is opalescent; flip off the lights, and streams of radiant color swirl through the tube. But before you start wrapping, pay a visit to Scientific American 's own Marketplace.