Helmholz Sound Synthesizer, circa 1905. Estimated value: $20,000 - $30,000 This incredibly rare example of the first electric keyboard, designed by Hermann Von Helmholtz, was built by Max Kohl, one of the most famous scientific instrument makers of his time. It may be the finest Helmholtz sound synthesizer still in existence.

Apple 1 Motherboard, 1976. Estimated value: $300,000 - $500,000 As the first pre-assembled personal computer on the U.S. market, the Apple 1 marks the beginning of the PC revolution. This motherboard is one of 50 that were hand-built by Steve Wozniak in Steve Jobs' garage. And this one still works.

Manhattan Project Window. Estimated value: $150,000 - $250,000 This 6-inch thick, 1,500-pound heavily-leaded hunk of glass allowed scientists to safely view production of plutonium for the secret WWII Manhattan Project that invented the atom bomb. No, the window is not radioactive.

Oil Painting of Bill Gates, 2000. Estimated value: $700 - $900 This Kramer-esque portrait of Bill Gates was painted for the November 2000 cover of WIRED by Michael Del Priore. The oil painting was also used for the cover of Pride Before the Fall by John Heilemann in 2003.

Pocket Globe, 1731. Estimated value: $8,000-$12,000 This 3-inch mini globe is made of paper mache and plaster with a fish-skin-covered wooden case. The inside of the case is a map of the constellations. One reason the globe is so valuable is that it depicts California as an island.

Magnavox Amplifier, 1921. Estimated value: $1,000 - $1,500 This early audio frequency amplifier was made by Magnavox Co. in Oakland, CA. The wooden case, knobs, switches and tubes are all in great condition.

Signed Photograph of Thomas Edison, 1887. Estimated value: $1,500 - $2,500 Thomas Edison sits in his laboratory dictating into a phonograph in this photo signed "Thos A Edison."

First Edition of Darwin's On the Origin of Species, 1859. Estimated value: $25,000 - $35,000 This is a first edition, first issue of one of the most important scientific works of all time. It has suffered a little wear and tear, is missing a few pages and has had several owners (including a monastery).

Astronomer George Willis Ritchey's Archive. Estimated value: $450,000 - $550,000 Ritchey (1864-1945) was a pioneering astronomer, astro-photographer and telescope designer. This collection of his life's work includes glass plates of celestial phenomena, photos, books, a 27-inch cellular mirror and the original patent for cellular mirror technology.

Magic Lantern, circa 1890. Estimated value: $2,000 - $3,000 Magic lanterns were an early form of the motion picture projector. This adorable one was made by the Pettibone Mfg. Co. Its 10 hand-colored glass slides show scenes including the Pyramids of Egypt, a scholar in his study, and a jungle scene with dragons and snakes.

Fabrizio's Collected Surgical Works, 1678. Estimated value: $1,200 - $1,800 First edition L'Opere Chirurgiche del Signor Girolamo Fabritio d'Aquapendente in Italian. This page shows a suit of orthopedic armor "designed to combine in one apparatus the principles for all existing devices for the correction of orthopedic injuries and deformities."

Olivetti Microcomputer, 1971. Estimated value: $2,000 - $3,000 This Italian microcomputer has four switches that read "Record Prog," "Print Prog," "Single Step" and "Second Side." Manuals included.

A Natural History of the Human Teeth, 1771-1778. Estimated value: $4,000 - $6,000 First edition of two of John Hunter's seminal works that laid the groundwork for the practice of dentistry. Hunter was the first to study teeth scientifically.

Refracting Telescope, circa 1900. Estimated value: $6,000 - $8,000 This 4-inch refracting telescope was built in Paris by Ateliers R. Mailhat. It is brass on heavy steel mount.

Machtonics Recorder, circa 1963. Estimated value: $2,000 - $3,000 This MV-11 Recorder was made by Machtronics of Mountain View, CA. It is 2 feet long and features video and audio-in knobs, audio bias and phase dials, fast forward, rewind, play, and record buttons, carrying handles and comes with original power cord and manual.

Sterling Audio Frequency Power Amplifier, 1922. Estimated value: $1,000 - $1,500 This early power amplifier, made in London by Sterling Telephone and Electric Co., was an important piece in the development of the modern telephone. It was manufactured under license with Motorola. Other than a few scratches, it looks like new.