The New Student's Reference Work/Rain-Gauge

Rain-Gauge, an instrument employed by meteorologists to measure the depths of water deposited by rain during any assigned period. In its ordinary form it consists of a funnel, with a mouth of known area, for collecting the rain-water in a graduated glass vessel where its mass can be easily determined. Knowing the mass of water precipitated and the area over which it was distributed, the depth may be easily calculated. Several forms of self-registering rain-gauges have been devised, for which see any good treatise on meteorology.