Keeping your food cold hundred years ago

The house I am living in, is probably around 110 years old.
When you walk up to the attic, you see this cupboard in the corner.

You open it and wonder what it was for.

You check it more carefully

and decide it was a cupboard for keeping the food cold.
A kind of primitive fridge with cold air coming from the outside through this opening.

My grandmother in Oslo used to keep her milk bottles in the kitchen window in the winter, an even simpler solution.
When I grew up in the mountains in the fifties and sixties one of our neighbours kept his milk in a little brook next to the house.
Fridges came later.....