In a Symons rain gauge, the collected rainfall is measured using:

Explanation:

A Symons rain gauge is a non-recording type of rain gauge. It collects rain in a cylindrical container, and the collected water is then measured using a measuring glass or cylinder with a graduated scale to determine the depth of rainfall manually, usually in millimeters.

Additional Information A digital display –

• Digital displays are used in modern automated rain gauges, not in the traditional Symons rain gauge.
• Symons rain gauge is a manual instrument and does not involve electronics or digital readouts.

A rotating drum –

• This is typically found in self-recording rain gauges (like the tipping bucket type with chart recorders), not in the Symons type.
• The Symons rain gauge does not use any mechanical recording device.

A pressure sensor –

• Pressure sensors are used in advanced weather instruments but are not part of the Symons rain gauge design.