We extend the formulae of classical invariant theory for the Jacobian of a genus one curve of degree n <= 4 to curves of arbitrary degree. To do this, we associate to each genus one normal curve of degree n, an n x n alternating matrix of quadratic forms in n variables, that represents the invariant differential. We then exhibit the invariants we need as homogeneous polynomials of degrees 4 and 6 in the coefficients of the entries of this matrix.