Let m(a, b) and M(a, b, c) be symmetric means. We say that M is type 1 invariant with respect to m if M(m(a, c),m(a, b),m(b, c)) ≡ M(a, b, c). If m is strict and isotone, then we show that there exists a unique M which is type 1 invariant with respect to m. In particular we discuss the invariant logarithmic mean L3, which is type 1 invariant with respect to L(a, b) = b−a log b−log a . We say th...