What, then, is the third possibility? That it may be a change in the conducting medium, in that infinitely fine ether which extends from star to star and pervades the whole universe. Deep in that ocean we are floating upon a slow current. Might that current not drift us into belts of ether which are novel and have properties of which we have never conceived? There is a change somewhere. This cosmic disturbance of the spectrum proves it. It may be a good change. It may be an evil one. It may be a neutral one. We do not know. Shallow observers may treat the matter as one which can be disregarded, but one who like myself is possessed of the deeper intelligence of the true philosopher will understand that the possibilities of the universe are incalculable and that the wisest man is he who holds himself ready for the unexpected. To take an obvious example, who would undertake to say that the mysterious and universal outbreak of illness, recorded in your columns this very morning as having broken out among the indigenous races of Sumatra, has no connection with some cosmic change to which they may respond more quickly than the more complex peoples of Europe? I throw out the idea for what it is worth. To assert it is, in the present stage, as unprofitable as to deny it, but it is an unimaginative numskull who is too dense to perceive that it is well within the bounds of scientific possibility.

"Yours faithfully, "GEORGE EDWARD CHALLENGER.

"THE BRIARS, ROTHERFIELD."

"It's a fine, steemulating letter," said McArdle thoughtfully, fitting a cigarette into the long glass tube which he used as a holder. "What's your opeenion of it, Mr. Malone?"

I had to confess my total and humiliating ignorance of the subject at issue. What, for example, were Fraunhofer's lines? McArdle had just been studying the matter with the aid of our tame scientist at the office, and he picked from his desk two of those many-coloured spectral bands which bear a general resemblance to the hat-ribbons of some young and ambitious cricket club.