The letters in our correspondence columns describing the appearance of a mirage in Shanghai have excited scientific interest. More than one person has witnessed the apparent phenomenon, but so far as can be gathered it is seen probably in Avenue Joffre only, and then at a distance of about a quarter of a mile, the special features being as described by the correspondent who: first called public attention to it. It is now pointed out that as the person advances, the mirage recedes, always keeping about the same distance. Now why should it! be practically confined to Avenue Joffre? The reasons given for this are distinctly interesting from the scientific point of view. In the first place, our principal informant tells us, it is not a real mirage at all. The asphalt of the road has been polished by the traffic until it acts as a mirror, and under a very strong sun throws back a reflexion of whatever may be in the vicinity. Naturally, this mirror effect can only be observed at some distance away, hence the fact that it always appears 400 or 500 yards ahead. Then comes its appearance almost solely in Avenue Joffre. The reason advanced for this is that practically nowhere else does the observer have a clear view for the requisite distance. Windings in the roads or other obstructions come into the line of sight elsewhere and prevent observation of something which is going on all the time and practically everywhere where as-halt or some similar substance is present to act as a mirror. This view of the case is distinctly plausible, but it must be admitted that there may be more in it than that.
Text read from the printed page and cleaned; old type leaves the occasional error.