One would naturally suppose that the extensive diffusion of sound scientific knowledge which has taken place during the century just past, would have placed these problems amongst the lumber of past ages; but it seems that some of them, particularly the squaring of the circle and perpetual motion, still occupy considerable space in the attention of the world, and even the futile chase after the "Elixir of Life" has not been entirely abandoned. Indeed certain professors who occupy prominent official positions, assert that they have made great progress towards its attainment. In view of such facts one is almost driven to accept the humorous explanation which De Morgan has offered and which he bases on an old legend relating to the famous wizard, Michael Scott. The generally accepted tradition, as related by Sir Walter Scott in his notes to the "Lay of the Last Minstrel," is as follows:

"Michael Scott was, once upon a time, much embarrassed by a spirit for whom he was under the necessity of finding constant employment. He commanded him to build a 'cauld,' or dam head across the Tweed at Kelso; it was accomplished in one night, and still does honor to the infernal architect. Michael next ordered that Eildon Hill, which was then a uniform cone, should be divided into three. Another night was sufficient to part its summit into the three picturesque peaks which it now bears. At length the enchanter conquered this indefatigable demon, by employing him in the hopeless task of making ropes out of sea-sand."

Whereupon De Morgan offers the following exceedingly interesting continuation of the legend:

"The recorded story is that Michael Scott, being bound by contract to procure perpetual employment for a number of young demons, was worried out of his life in inventing jobs for them, until at last he set them to make ropes out of sea-sand, which they never could do. We have obtained a very curious correspondence between the wizard Michael and his demon slaves; but we do not feel at liberty to say how it came into our hands. We much regret that we did not receive it in time for the British Association. It appears that the story, true as far as it goes, was never finished. The demons easily conquered the rope difficulty, by the simple process of making the sand into glass, and spinning the glass into thread which they twisted. Michael, thoroughly disconcerted, hit upon the plan of setting some to square the circle, others to find the perpetual motion, etc. He commanded each of them to transmigrate from one human body into another, until their tasks were done. This explains the whole succession of cyclometers and all the heroes of the Budget. Some of this correspondence is very recent; it is much blotted, and we are not quite sure of its meaning. It is full of figurative allusions to driving something illegible down a steep into the sea. It looks like a humble petition to be allowed some diversion in the intervals of transmigration; and the answer is:

"'Rumpat et serpens iter institutum'

"a line of Horace, which the demons interpret as a direction to come athwart the proceedings of the Institute by a sly trick."

And really those who have followed carefully the history of the men who have claimed that they had solved these famous problems, will be almost inclined to accept De Morgan's ingenious explanation as something more than a mere "skit." The whole history of the philosopher's stone, of machines and contrivances for obtaining perpetual motion, and of circle-squaring, is permeated with accounts of the most gross and obvious frauds. That ignorance played an important part in the conduct of many who have put forth schemes based upon these pretended solutions is no doubt true, but that a deliberate attempt at absolute fraud was the mainspring in many cases cannot be denied. Like Dousterswivel in "The Antiquary," many of the men who advocated these delusions may have had a sneaking suspicion that there might be some truth in the doctrines which they promulgated; but most of them knew that their particular claims were groundless, and that they were put forward for the purpose of deceiving some confiding patron from whom they expected either money or the credit and glory of having done that which had been hitherto considered impossible.

Some of the questions here discussed have been called "scientific impossibilities"—an epithet which many have considered entirely inapplicable to any problem, on the ground that all things are possible to science. And in view of the wonderful things that have been accomplished in the past, some of my readers may well ask: "Who shall decide when doctors disagree?"

Perhaps the best answer to this question is that given by Ozanam, the old historian of these and many other scientific puzzles. He claimed that "it was the business of the Doctors of the Sorbonne to discuss, of the Pope to decide, and of a mathematician to go straight to heaven in a perpendicular line!"

In this connection the words of De Morgan have a deep significance. Alluding to the difficulty of preventing men of no authority from setting up false pretensions and the impossibility of destroying the assertions of fancy speculation, he says: "Many an error of thought and learning has fallen before a gradual growth of thoughtful and learned opposition. But such things as the quadrature of the circle, etc., are never put down. And why? Because thought can influence thought, but thought cannot influence self-conceit; learning can annihilate learning; but learning cannot annihilate ignorance. A sword may cut through an iron bar, and the severed ends will not reunite; let it go through the air, and the yielding substance is whole again in a moment."