# First appearance of tensor product symbol $\otimes$

I was asked recently if the tensor product symbol $\otimes$ had been used before Bourbaki's publication on multilinear algebra in 1948 (a draft of this document can be seen at http://sites.mathdoc.fr/archives-bourbaki/PDF/040_iecnr_049.pdf starting on p. 10). I was unable to find any earlier usage, so that leads to my question:

Who introduced the symbol $\otimes$ for use in tensor products?

• While we're at it, when was that exact same symbol used to indicate a basis vector pointing "down into the page" in vector diagrams? – Carl Witthoft Feb 1 '18 at 12:45