HSTJE-SHEN TSIEN 1 has given a method for designing x i —. e(/') ^ ^ contraction cones for wind tunnels. This is t a n ^ ~ = ^ i e-^x/a) = 1 + 2 / j(— l) e quite accuiate theoretically but requires complicated m=l numerical calculations. A different solution is given f or 0 < ^ < oo below. While equally exact, it is simpler and easier The stream function \p fulfils the equation: t a n h = t{x/a) = — 1 — 2 /](~-l) e' in its application.! x eH*/a) __ ^ x°°^ ( (8) : t