Historians believe Pilgrims brought thunder glasses to the colonies in the 1620's and these simple devices continue to intrigue weather watchers today. Some the of the earliest meteorological instruments were made possible by the skill of 17th century European glass blowers. The tradition of combining glass blowing with science continues today as exemplified by this fine hand-crafted piece. Changes in air pressure cause the water to rise and fall in the spout. Low water level indicates high pressure and fair weather, while rising water means low pressure and inclement weather. Made in Europe of borosilicate glass. Etched on calibration marks aid the process of interpreting liquid levels. Each glass is supplied with instructions and carefully packed in a strong individual box to resist damage in shipment. Measures 9 inches high by 4 1/2 inches wide