Galileo Thermometers are magnificent creations that make Galileo’s 400 year old principle of relative density a functional reality. An accurate indoor thermometer encased in brilliant glass, the Galileo is the point at which art meets science. Galileos add sparkle and focus to any setting: Galileos are precisely manufactured. Each of the liquid-filled floats weighs exactly.006 grams more than the one above it in the cylinder to ensure a stately and orderly procession of ups and downs as the temperature changes. The fluid in the floats and the cylinder has to be exactly the same density for the thermometer to function properly. The fluid is non-toxic and non-hazardous, an inert oil/hydrocarbon mixture like mineral oil: Galileos are carefully packaged. The cylinder walls are laboratory grade glass, so sturdiness isn’t an issue. A cardboard box sleeve surrounds a form-fitted foam case that virtually guarantees safe arrival: This fascinating, functional instrument is the point at which science meets art. Four hundred years ago Galileo discovered that specifically weighted floating bubbles would predictable rise or sink in a liquid as the temperature of that liquid is changed. These decorative glass reproductions of Galileo’s discovery have glass floats precisely weighted in.006 gram increments suspended in a clear, environmentally safe, non-toxic liquid. Simply read the tag on the lowest floating bubble to read the temperature – Each tag is marked in Fahrenheit on both sides of the tag. The 11 inch measures every 4 degrees from 64 F to 80 F and is accurate to within 2 degrees with five floats.