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Member Products:21-inch Galileo Thermometer

21-inch Galileo Thermometer


Price: $60.00

Item# :2000379

Qty: This item is out of stock

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Art meets science in this colorful glass thermometer. In 1593, Italian physicist Galileo invented a thermometer based on the principles of relative density. Individually calibrated weights containing a mixture of ethanol and dye float in a sealed tube with de-aromatic oil where they rise and fall with the temperature and the resulting changes in liquid density.

Not available for shipment outside of the 48 contiguous United States. Expedited shipping is not available for these items. This item cannot ship to a PO/APO/FPO Box.

Displays temperatures in Fahrenheit in 2° increments from 68° to 80°. Accurate to within 2°. 21"H.

In the 2nd century B.C., Greek scholar Archimedes discovered the law that states any object in a fluid displaces its own weight of fluid. He went a step further when he described the principle of buoyancy—that if an object is more dense than an equal volume of water, it sinks; if it's less dense, it floats. A simplified way of understanding density in this example is that it's the relative "heaviness" of objects of the same volume—a marshmallow is less dense than a marble of the same size and shape.

Almost 2,000 years later, Italian scientist Galileo discovered that a liquid's density is affected by changes in temperature. As temperatures rise, a liquid's density decreases. This means that objects that float in room temperature water would sink as the water is heated. He applied his discovery to create what is now known as a Galileo thermometer.

In a Galileo thermometer, sealed glass bubbles filled with a mixture of ethanol and dye have weights attached that are marked with different degrees Fahrenheit. The bubbles are suspended in a tube of de-aromatic oil. The weights give the bubbles different densities from each other and from the liquid in the tube.

When the atmospheric temperature rises, the density of liquid in the tube decreases, which changes the relative density of the glass bubbles. So, as the temperature increases, the liquid's density decreases, which means more bubbles will sink because they are now more dense than the surrounding liquid. At the highest temperatures, the lightest (least dense) bubble will finally sink. When temperatures drop, the opposite happens and more bubbles rise.

To read a Galileo thermometer, look at the lowest hanging bubble in the middle of the tube—the one that is not entirely sunk, nor entirely floating at the top. This bubble is in equilibrium with the surrounding liquid, and its tag will tell the current temperature.


by PowerReviews
21-inch Galileo Thermometer

(based on 3 reviews)

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very nice looking


from Mankato, MN

Verified Reviewer



    • Arrived broken

    Best Uses

      Comments about 21-inch Galileo Thermometer:

      have not been able to enjoy product as it arrived broken and have not received a replacement yet


      21-inch Galileo Thermometer

      By lbn

      from Murrysville, Pa

      Verified Buyer

      Comments about 21-inch Galileo Thermometer:

      My grandson liked it.

      (1 of 1 customers found this review helpful)


      Great show piece that works perfect

      By Artie50

      from Nashua NH

      Verified Buyer

      Comments about 21-inch Galileo Thermometer:

      excellent piece, looks great in my living room. Only issues was first one was broken (it is glass), they replaced it at no cost to me. NG is great to deal with.

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