I think the 'hole' in which the waxine candles are set, should be attached to the lower part of the thickness of the table top (huh? I must read that again). i.e. the outside of the glass cilinder should not go to the top of the top. And maybe you should try of another refraction value is needed. But I think it is a matter of adding an extra cross-section and take the real-world construction in consideration. I might very well be wrong, but it is the most logical explanation (not the most logical way of trying to explain it probably ;-)