How it works
A 40 BPM metronome clicks at the number where wind-up metronomes begin: Wikipedia's Metronome article gives a mechanical one a usual span of 40 to 208. In Wikipedia's list of tempo markings, Grave ends here and Largo starts.
Read the full guide
Start
Tap the pad, or press Space. Four unhurried clicks make a bar and the first is the higher one. Tap again to stop.
Change the tempo
Tap the number under the pad to type another tempo, or press plus: each press adds a single beat a minute, so 41 is one press away.
Questions and answers
Is 40 BPM largo or grave?
Both, at their edges. Wikipedia's list of tempo markings runs Adagissimo and Grave, very slow and solemn, from 24 up to 40, and starts Largo (to 66) and Lento (to 60) at 40. It says its figures are only loose guides for 4/4.
What is the next metronome setting above 40?
On a wind-up one, usually 42. The arrangement Wikipedia's Metronome article calls the most common climbs in twos from 40 as far as 60, then in threes to 72. Scales vary from maker to maker, and this pad plays the odd numbers too.
Can a metronome go slower than 40 BPM?
A wind-up one usually cannot. This one can: press minus, or type a number, for any whole tempo down to 1. Wikipedia's list of tempo markings keeps Grave as far down as 24 and calls anything slower Larghissimo, extremely slow.
Who gave the metronome its numbered scale?
Johann Maelzel. Wikipedia's Metronome article credits the spring-powered pendulum to Dietrich Nikolaus Winkel, who devised it in Amsterdam in 1814; Maelzel took up the idea, added a scale of numbers, patented the result in 1815 and made it under his own name from 1816.
Why can't I hear the metronome?
Clicks at 40 are far apart, so wait for a second one. If none comes, look at the phone's ring switch, its volume, and whether Bluetooth headphones have taken the sound. The four dots go on lighting in turn either way.