A musical instrument that produces whistle-type tones responsive to the impingement of sunlight or other source of electromagnetic radiation upon one or more radiation-absorbent porous-to-air, generally disc-shaped generator member or members disposed interiorly and in the lower half of a vertically oriented transparent or partially transparent tube with angled open ends. The generator member or members may be in the form of a wire mesh or gauze. In a preferred embodiment, Fresnel lenses are employed to focus sunlight on the generators contained within a plurality of tubes of differing lengths that are grouped together to form a musical instrument suitable for display in public places for the entertainment and scientific edification of the public.