Why are notes on the harmonica laid out the way they are?

We use this to develop single note playing and movement around the harp. Simple as it may seem, it's a great way of learning to navigate the new instrument and to develop an aural awareness of the changes that take place (as we cannot actually see them under our nose).

1. Why are harmonicas tuned the way they are?
2. Where is middle C on a harmonica?

Why are harmonicas tuned the way they are?

Named after the 19th century harmonica maker, Joseph Richter, who developed the tuning, it provides the tonic and dominant chords in the lower part of the harmonica (C and G Major, in the example of a C Major Richter tuned harp shown below) and the relevant scale (in the example below, C Major) between holes 4 and 7.

Where is middle C on a harmonica?

The first hole blow note will be C4. To put this into a more easily visualised context, C4 is also known as middle C, and is found very close to the middle of most piano keyboards. The 10th hole blow note will also be a C, but it will be 3 octaves higher, making it a C7.