We use the Weil representation
to evaluate certain Gauss sums over a local field, up to ±1. Also we construct a
cocycle on Sp(2m, ℝ) with a simple formula on the maximal compact torus and we
show how to lift homomorphisms j :Sp(2n, ℝ) →Sp(2m, ℝ) to the double covers of
these groups.