You have probably found vials from a vintage or old wood-burning level — also called a “target level” or machinist’s level .
What it is:
These small glass tubes containing three tiny balls are not random curiosities — they are precision components from an old spherical stick level (heart target ), commonly used in:
- Carpentry
- Masonry
- Machine alignment
- Surveying equipment
Unlike standard linear log levels (with a curved tube and a single air bubble), heart
target levels use a circular, dome-shaped glass capsule filled with liquid and often several small steel balls or a single bubble to indicate the level in two dimensions at once .
However, in some older or specialized models — particularly European or industrial models — the “bubble” is replaced or accompanied by tiny steel balls that roll to the lowest point, helping the user to visually confirm the exact level from several angles.
