Thousands of flights are undertaken every day with the confident expectation of a successful trip and return. How many, many boys and mechanics, prior to the achievement of human flight, have been attracted by the problem, only to have their ambitions and dreams discouraged and suppressed by being told that the scientific world knows that human flight is impossible—"God made man to walk on the ground, and the birds to fly, and if Nature had intended that we should fly we would have been equipped with wings," and probably to be dubbed "Darius Green," as a reminder of the inglorious fate of the pseudo hero of that name in Trowbridge's clever and immortal poem about Darius Green and his Flying Machine.

The announcement of the discovery of rays by means of which views may be made and photographs taken through substances supposedly opaque to all light rays was scouted as a ridiculously visionary dream; but the discoverers were not dismayed by scout and ridicule, but persisted in their dreams and enthusiasm. There is not a village of any considerable size in the civilized world but has its X-Ray Machine by which foreign substances in the flesh may be viewed and photographed and located with exactitude, fractures examined and all surgical operations aided to the benefit and health and recovery of the sick and wounded. Mankind is the recipient of the benefits resulting from the fact that enthusiastic cranks were not deterred by ridicule and supposed demonstrations of their folly.

The above are only a few of the many like instances recorded in scientific progress. While not accurately true, and while less true during the last two decades than formerly, it is, nevertheless, a general truth that scientific progress has been made in spite of, and in the face of discouragement and ridicule from the multitudes who were destined to be benefited by the discoveries made by the persistent so-called cranks.

These facts are all well known to the Perpetual Motion enthusiast. It is, therefore, of no avail to tell him that the scientific world has pronounced his aspirations and attempts but dreams, and that Perpetual Motion workers are by the scientific world denominated cranks.

If it be admitted that Perpetual Motion is, as scientific men tell us, a chimerical dream, it is still to be very greatly doubted if the world at large is to be benefited by dissuading minds from working on the problem. There is no doubt that many persons who have become more intensely interested in mechanics by thinking and working on the problem of Perpetual Motion, have thereby been lead to study more and more generally into mechanical subjects, and became not merely tyros, but useful men in various mechanical pursuits. Many doubtless have followed mechanical subjects to which they were introduced by labors toward Perpetual Motion, to the making of useful and valuable inventions and discoveries.

Notwithstanding the fact that a countless number of devices for the attainment of Perpetual Motion have been proclaimed and exhibited, it is to be supposed that those actually proclaimed and brought to light constitute but an infinitesimally small proportion of those actually made. It is to be supposed that the Perpetual Motion worker has some sense, and that the great majority of them before proclaiming his apparatus would want to know himself that it was not a failure, and would not, when ushered before the public, bring upon him humiliation and jeers. It is to be believed that in nearly every instance the produced device was tested before being proclaimed and ushered into the light of day. It goes without saying that all that were so tested were failures, and were never heard of except by the inventor and a very few intimate friends or co-laborers. Those that have been heralded to the world represent only that small proportion where over-confidence in the operation, or a disregard for the truth, or some other unexplainable something caused the inventor and his friends to make the announcement and disclosure of the device before the test.

It is almost impossible to conceive of a person of any intelligence exposing himself to the ridicule resulting from the failure of a pompously heralded device, when a simple test would have saved the exposure, and yet the civilized world has been filled with Perpetual Motion devices proclaimed and heralded with trumpet blast, which, when tested, "didn't work."

It is not, however, the purview, or purpose of this book, to incite people to work on the problem of Perpetual Motion, neither is it its purview or purpose to dissuade them from it.

In the works of Mr. Dircks, mentioned in the preface of this work, the devices for Perpetual Motion are classified somewhat with reference to the time each was produced. In some instances with reference to whether or not patents were applied for and obtained, or as to the source of information concerning them.

A careful examination of the devices presented in Mr. Dirck's two works, and of those, information concerning which has been obtained elsewhere, leads the author to believe that nothing is to be gained by an attempted classification along those lines.