The longitude (abbreviation: Long., Î», or lambda) of a point on the Earth's surface is the angle east or west from a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses (often improperly called great circles), which converge at the north and south poles.
Use the dual thermometers to calculate relative humidity. Fisher Scientific Mason's Hygrometer has one dry thermometer and one wet thermometer which provide temperature readings for determining the relative humidity.
A bimetal Insta-Read dial thermometer may lose accuracy after years of use or after a particularly hard jolt. The hex nut on the underside of the thermometer is used to bring the thermometer back into calibration. First, you need a container of water at a known temperature-the closer to the mid-range the better.