Solar Radiometer with Short Solid Stem - 80mm clear glass globe
This Solar Radiometer is made by traditional Thuringian hand-blowing in Germany, of crystal-clear Lauschaer bottle glass. In the glass body is a 4-vane drive assembly, which turns under the influence of light. One side of each vane is black, the other is silver. Height: ca. 15cm. (6 in) Globe diameter: ca. 8cm. (3. 25 in) Solar radiometers won't turn under all lights, such as fluorescents, unless they are close to it. The best source of light is the Sun, or an incandescent bulb. Try placing it near a table lamp, or a torch. The light needs to be warm rather than cold. The Crookes radiometer, also known as the light mill or solar engine, consists of an airtight glass bulb, containing a partial vacuum. Inside are a set of vanes which are mounted on a spindle. The vanes rotate when exposed to light. The reason for the rotation has been the cause of much scientific debate. It was invented by the chemist Sir William Crookes as the by-product of some chemical research. In the course of very accurate quantitative chemical work, he was weighing samples in a partially evacuated chamber to reduce the effect of air currents, and noticed the weighings were disturbed when sunlight shone on the balance. Investigating this effect, he devised the device named after him, still manufactured and sold to this day as a curiosity item.