A tally counter is a mechanical, electronic, or software device used to incrementally count something, typically fleeting. One of the most common things tally counters are used for is counting people, animals, or things that are quickly coming and going from some location.
Description
A tally counter is usually cased in metal and is cylindrical in shape. Part of the circle is flattened out and contains a window of plastic or glass. Inside the counter are a number of rings with the numbers from 0 to 9 in descending order going clockwise. Most counters have four such rings, allowing the user to count up to 9999. A metal ring may be attached to aid in holding the counter, and usually half the ring is bent to allow it to fold flush with the counter when not in use.
The counter is activated by pressing a button located above the screen. This causes the first ring to advance one number. After the count has reached 0009, then the second ring will advance one click and the first ring will come back to zero displaying 0010. To reset the counter, a knob is located on the side. This knob turns all the rings which are displaying the same number (usually zero). When the number displayed reaches the number on the remaining rings, then they will turn too, until the display is reset back to 0000. (Analog odometers in vehicles operate in a similar fashion.)