CHAPTER III

THE ART OF MAKING A WHEEL OF PERPETUAL MOTION

In this chapter I will make known to you the construction of a wheel which in a remarkable manner moves continuously. I have seen many persons vainly busy themselves and even becoming exhausted with much labor in their endeavors to invent such a wheel. But these invariably failed to notice that by means of the virtue or power of the lodestone all difficulty can be overcome. For the construction of such a wheel, take a silver capsule like that of a concave mirror, and worked on the outside with fine carving and perforations, not only for the sake of beauty, but also for the purpose of diminishing its weight. You should manage also that the eye of the unskilled may not perceive what is cunningly placed inside. Within let there be iron nails or teeth of equal weight fastened to the periphery of the wheel in a slanting direction, close to one another so that their distance apart may not be more than the thickness of a bean or a pea; the wheel itself must be of uniform weight throughout. Fasten the middle of the axis about which the wheel revolves so that the said axis may always remain immovable. Add thereto a silver bar, and at its extremity affix a lodestone placed between two capsules and prepared in the following way: When it has been rounded and its poles marked as said before, let it be shaped like an egg; leaving the poles untouched, file down the intervening parts so that thus flattened and occupying less space, it may not touch the sides of the capsules when the wheel revolves. Thus prepared, let it be attached to the silver rod just as a precious stone is placed in a ring; let the north pole be then turned towards the teeth or cogs of the wheel somewhat slantingly so that the virtue of the stone may not flow diametrically into the iron teeth, but at a certain angle; consequently when one of the teeth comes near the north pole and owing to the impetus of the wheel passes it, it then approaches the south pole from which it is rather driven away than attracted, as is evident from the law given in a preceding chapter. Therefore such a tooth would be constantly attracted and constantly repelled.

In order that the wheel may do its work more speedily, place within the box a small rounded weight made of brass or silver of such a size that it may be caught between each pair of teeth; consequently as the movement of the wheel is continuous in one direction, so the fall of the weight will be continuous in the other. Being caught between the teeth of a wheel which is continuously revolving, it seeks the centre of the earth in virtue of its own weight, thereby aiding the motion of the teeth and preventing them from coming to rest in a direct line with the lodestone. Let the places between the teeth be suitably hollowed out so that they may easily catch the body in its fall, as shown in the diagram above. (Fig. 4.)

Farewell: finished in camp at the siege of Lucera on the eighth day of August, Anno Domini MCCLXIX.

NOTES

EARLY REFERENCES TO THE MARINER’S COMPASS

The following are the passages referred to in the introductory notice:

Abbot Neckam (1157-1217), in his _De Naturis Rerum_, writes:

“The sailors, moreover, as they sail over the sea, when in cloudy weather they can no longer profit by the light of the sun, or when the world is wrapped up in the darkness of the shades of night and they are ignorant to what point their ship’s course is directed, these mariners touch the lodestone with a needle, which (the needle) is whirled round in a circle until when its motion ceases, its point looks direct to the north. (_Cuspis ipsius septentrionalem plagam respiciat._)”

In his _De Utensilibus_, we read:

“Among other stores of a ship, there must be a needle mounted on a dart (_habeat etiam acum jaculo superpositam_) which will oscillate and turn until the point looks to the north, and the sailors will thus know how to direct their course when the pole star is concealed through the troubled state of the atmosphere.”[5]

Alexander Neckam was born at St. Albans in 1157, joined the Augustinian Order and taught in the University of Paris from 1180 to 1187, after which he returned to England to take charge of a College of his Order at Dunstable. He was elected Abbot of Cirencester in 1213 and died at Kemsey, near Worcester, in 1217.

The satirical poem of Guyot de Provins, written about 1208, contains the following passage:

The mariners employ an art which cannot deceive, By the property of the lodestone, An ugly stone and brown, To which iron joints itself willingly They have; they attend to where it points After they have applied a needle to it; And they lay the latter on a straw And put it simply in the water Where the straw makes it float. Then the point turns direct To the star with such certainty That no man will ever doubt it, Nor will it ever go wrong. When the sea is dark and hazy, That one sees neither star nor moon, Then they put a light by the needle And have no fear of losing their way. The point turns towards the star; And the mariners are taught To follow the right way. It is an art which cannot fail.

Provins, from which Guyot took his surname, was a small town in the vicinity of Paris.

Cardinal Jacques de Vitry, in his _Historia Orientalis_, Cap. 89, writes:

“An iron needle, after having been in contact with the lodestone, turns towards the north star, so that it is very necessary for those who navigate the seas.”

Jacques de Vitry was born at Argenteuil, near Paris, joined the fourth crusade, became Bishop of Ptolemais, and died in Rome in 1244. He wrote his “Description of Palestine,” which forms the first book of his _Historia Orientalis_, in the East, between 1215 and 1220.

Albertus Magnus (1193-1280) in his _De Mineralibus_, Lib. II., Tract 3, Cap. 6, writes:

“It is the end of the lodestone which makes the iron that touched it turn to the north (_ad zoron_) and which is of use to mariners; but the other end of the needle turns toward the south (_ad aphron_).”

This illustrious Bavarian schoolman joined the Dominican Order in his youth, lectured to great audiences in Cologne, became bishop of Ratisbonne in 1260, and died in 1280. Thomas Aquinas the greatest of schoolmen, was among his pupils.

In the Spanish code of laws, begun in 1256, during the reign of Alfonso el Sabio, and known as _Las Siete Partidas_, we read:

“Just as mariners are guided during the night by the needle, which replaces for them the shores and pole star alike, by showing them the course to pursue both in fair weather and foul, so those who are called upon to advise the King must always be guided by a spirit of justice.”

Brunetto Latini, in his _Trésor des Sciences_, 1260, writes:

“The sailors navigate the seas guided by the two stars called the tramontanes, and each of the two parts of the lodestone directs the end of the needle to the star to which that part itself turns.”

Brunetto Latini (1230-1294) was a man of great eminence in the thirteenth century; Dante was among his pupils at Florence. For political reasons, he removed to Paris, where he wrote his _Trésor_ and also his _Tesoretto_. He visited Roger Bacon at Oxford about 1260.

In his treatise _De Contemplatione_, begun in 1272, Raymond Lully writes:

“As the needle, after having touched the lodestone, turns to the north, so the mariner’s needle (_acus nautica_) directs them over the sea.”

Lully was born at Palma in the Island of Majorca in 1236; he joined the Third Order of St. Francis, dying in 1315.

Ristoro d’Arezzo, in his _Libro della Composizione del Mundo_, written in 1282, has the following:

“Besides this, there is the needle which guides the mariner, and which is itself directed by the star called the tramontane.”[6]

The following metrical translation of a poem by Guido Guinicelli, an Italian priest, 1276, is from the pen of Dr. Park Benjamin, of New York:

In what strange regions ’neath the polar star May the great hills of massy lodestone rise, Virtue imparting to the ambient air To draw the stubborn iron; while afar From that same stone, the hidden virtue flies To turn the quivering needle to the Bear In splendor blazing in the Northern skies.

The above extracts show that the directive property of the magnetic needle was well known in England, France, Germany, Spain and Italy in the thirteenth century. In the passage from Neckam, the _acum jaculo superpositam_ has been construed by some to mean a form of pivoted needle, while in the letter of Peregrinus, 1269, the double pivoted form is clearly described.

Footnotes

[1]With very few exceptions all the works referred to in this notice will be found in the Wheeler Collection in the Library of the American Institute of Electrical Engineers, New York.

[2]It is probable that Flavio Gioja, an Italian pilot, some fifty years later, added the compass-card and attached it to the magnet.

[3]Annali di Matematica Pura ed Applicata, 1865.

[4]A terrella, or earthkin.

[5]The Chronicles and Memoirs of Great Britain and Ireland during the Middle Ages, by Thomas Wright (1863).

[6]The pole-star was thus named in the south of France and the north of Italy because seen beyond the mountains (the Alps).

Transcriber’s Notes

—Retained publication and copyright information from the original; this eBook is public-domain in the U.S.

—Silently corrected a few palpable typographical errors.

—In the text versions, enclosed italicized text in _underscore_.