Please can someone explain the function of this level? Why the two torpedo tubes beside one another and why don't they match?

Level with 6 Torpedo Tubes

  • 8
    FYI, "torpedo" refers to a small, pocket-sized level, not the vial.
    – isherwood
    Commented Dec 6, 2023 at 21:22
  • Vial doesn't seem the right word to me either but I have no clue what they should be called which seems odd to me that I don't know what t o call them
    – CityguyUSA
    Commented Dec 8, 2023 at 0:38
  • I don't get "they will match when oriented appropriately". If someone could post a video of how this is used that would be helpful.
    – CityguyUSA
    Commented Dec 8, 2023 at 0:42

1 Answer 1


A careful carpenter will flip a single-vial level 180 degrees to check for deviation in a level or plumb line. This arrangement improves accuracy without the need to do that.

Also, some levels have vials which are curved as opposed to having a center bulge. In that case, you'd read the tube with the upward-arching tube. That's likely the case with this one, which is why the bubbles don't seem to agree.

Then, if you have both arches at all locations you don't have to flip the level over to have one at eye level.

  • 1
    Yup, that's a classic curved tube level made to be usable in multiple orientations. When the level vial was a more precious commodity, you got just one of them for level and one for plumb, and it was up to you to orient the level so it was right-way-up & worked. With this setup, normally the curves go to the center, so the lower tube is the one that will read correctly.
    – Ecnerwal
    Commented Dec 7, 2023 at 2:14
  • 3
    Can you elaborate on the "curved vs bulge" thing? This concept is new to me, and I am having an hard time imagining/understanding what you are talking about. Thanks! Commented Dec 7, 2023 at 14:34
  • 1
    Barrel-shaped. Internal curve vs. external/full curve.
    – isherwood
    Commented Dec 7, 2023 at 14:34

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