Some Galileo thermometers have a decorative base, often made of wood. The type of wood and finish vary, so you can match the thermometer to your décor. In the Galileo thermometer, the small glass bulbs are partly filled with different-colored liquids. The composition of these liquids is mainly water; some contain a tiny percent of alcohol, but that is not important for the functioning of the thermometer; they merely function as fixed weights, with their colors denoting given temperatures. Once the hand-blown bulbs have been sealed, their effective densities are adjusted using the metal tags hanging from beneath them. Any expansion due to the temperature change of the colored liquid and air gap inside the bulbs does not affect the operation of the thermometer, as these materials are sealed inside a glass bulb of fixed size. The clear liquid in which the bulbs are submerged is not water, but some organic compounds (such as ethanol or kerosene) the density of which varies with temperature more than water does. Temperature changes affect the density of the outer clear liquid and this causes the bulbs to rise or sink accordingly. [2] Gallery [ edit ] The Galileo thermometer includes a glass tube filled with liquid. In the past, this was an ethanol mixture or even wine, but today it’s typically mineral oil. Inside the cylinder are several small glass bulbs, each filled with a colored liquid, either alcohol or water with food coloring. The bulbs are designed to have the same density. The Galileo thermometer is a centuries-old device that measures temperature. It typically sits on a shelf or table and includes a glass cylinder filled with liquid within which are small glass bulbs filled with different colors of liquid. These bulbs rise and fall as the temperature changes. While it might take some time to learn to read the thermometer, it is a fairly accurate device that can add a bit of ornamentation and sophistication to any room.

Most Galileo thermometers are tall, cylindrical tubes, but there are also some innovative options that are large spheres. These use the same principle but offer a significantly different aesthetic. The spheres may also be attached to a base or suspended by a stand, not unlike those with some glass whiskey decanters. Colors Modern Galileo thermometers for use in a home have a limited temperature range such as you would find in such a space. Most offer temperature readings between 64°F and 80°F. What’s more, because there is a limited number of bulbs in the cylinder, they don’t correspond to every temperature. For example, a basic Galileo thermometer has five bulbs tagged with 64°F, 68°F, 72°F, 76°F, and 80°F. Attached to each bulb is a weighted tag with a number that indicates a temperature. The weights are calibrated to slightly change the density of the bulbs. When the air temperature around the cylinder changes, the water temperature inside it changes, changing the density of the water. Water density decreases as temperature increases, and vice versa. When the density of the water changes, the bulbs either float or sink. To find the temperature, you look for the bulb that’s suspended near the middle of the cylinder, ignoring those that float to the top or sink to the bottom. Size Larger Galileo thermometers that include more bulbs offer more precision. Some options have as many as 10 or more bulbs. The more bulbs, the wider the cylinder. And more bulbs offer greater precision and a wider temperature range, from as low as 60°F in some cases to 100°F. Added devices The Galileo thermometer functions on a basic principle of physics championed by Galileo: buoyancy. He challenged Aristotle, positing that whether or not an object would float depends on the corresponding densities of the object and the liquid. FAQ Q. How do I read the thermometer if there’s no bulb floating in the middle of the unit?A. In some cases, the bulbs may all be at the top or bottom of the cylinder. In that case, look for the numbers on the bulbs and where the bulbs are located. With a cluster of high-temperature bulbs at one end and a cluster of low-temperature bulbs at the other, the actual temperature is in between those two ranges. To determine a more exact temperature, note the lowest hanging bulb at the top and the highest bulb at the bottom. Add the two numbers and divide by two to calculate the current temperature. Q. How precise is a Galileo thermometer? A. While a Galileo thermometer can be used outside to measure the temperature, it should be done so with caution and only for a short period of time. It shouldn’t be left outside in inclement weather because the unit is relatively fragile and the liquids may freeze if the temperature drops low enough. The science behind the thermometer was discovered 400 years ago by Galileo - he found that specifically weighted floating bubbles would predictably rise or sink in a liquid as the temperature of the liquid changed. Each float within the glass case weighs just grams more than the one above it, and the tags on which temperature is marked are attached to them by hand to ensure accuracy. Although named after the 16th–17th-century physicist Galileo, the thermometer was not invented by him. (Galileo did invent a thermometer called Galileo's air thermometer, more accurately called a thermoscope, in or before 1603.) [1] Galileo thermometers vary in size, but this doesn’t affect their function. Size does affect where you can display the device and how it looks. Most are between 8 and 15 inches tall, though there are bigger ones, some as tall as 24 inches.

This incredible indoor thermometer is based on Galileo's 400-year-old principle of relative density. You can simply read the tag on the lowest floating coloured bubble to see the temperature of the room. Based on a thermoscope invented by Galileo Galilei in the early 1600s, the thermometer on your co-worker's desk is called a Galileo thermometer. A simple, fairly accurate thermometer, today it is mostly used as decoration. The Galileo thermometer consists of a sealed glass tube that is filled with water and several floating bubbles. The bubbles are glass spheres filled with a colored liquid mixture. This liquid mixture may contain alcohol, or it might simply be water with food coloring. A Galileo thermometer (or Galilean thermometer) is a thermometer made of a sealed glass cylinder containing a clear liquid and several glass vessels of varying density. The individual floats rise or fall in proportion to their respective density and the density of the surrounding liquid as the temperature changes. It is named after Galileo Galilei because he discovered the principle on which this thermometer is based—that the density of a liquid changes in proportion to its temperature. Other Galileo thermometers are simply paired with a globe-shaped glass barometer that’s also filled with a colored liquid. Base or hook The device now called the Galileo thermometer was revived in the modern era by the Natural History Museum, London, which started selling a version in the 1990s. [6] Operation [ edit ]The instrument now known as a Galileo thermometer was invented by a group of academics and technicians known as the Accademia del Cimento of Florence, [2] who included Galileo's pupil, Torricelli and Torricelli's pupil Viviani. [3] [4] Details of the thermometer were published in the Saggi di naturali esperienze fatte nell'Academia del Cimento sotto la protezione del Serenissimo Principe Leopoldo di Toscana e descritte dal segretario di essa Accademia (1666), the academy's main publication. The English translation of this work (1684) describes the device ('The Fifth Thermometer') as 'slow and lazy', a description that is reflected in an alternative Italian name for the invention, the termometro lento (slow thermometer). [5] The outer vessel was filled with 'rectified spirits of wine' (a concentrated solution of ethanol in water); the weights of the glass bubbles were adjusted by grinding a small amount of glass from the sealed end; and a small air space was left at the top of the main vessel to allow 'for the Liquor to rarefie' (i.e. expand). Knowing the temperature is important, useful information; the means of gauging that temperature, however, can take a lot of forms. The Galileo thermometer, named for the famed Italian scientist, offers both functionality and aesthetics when it comes to measuring the temperature in a room. It’s possible to make your own Galileo thermometer at home. It requires a glass vase, sealed glass canisters, measuring equipment, and some careful scientific calculations. Key considerations Invention Some options do not have a base and instead include a metal frame and hook or just a hook so the thermometer can be hung. Shape Thermometer containing several glass vessels of varying density A Celsius Galilean thermometer in two degree gradations. A risen orange orb denotes 24 °C.