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.
by: Rake. Hygrometer is basically a device that is used to measure the humidity of a particular place. Humidity is basically the moisture content in the air. The olden ways of measuring this was used by metal strips and now we have got electronic apparatus which works with the help of sensors.