Spanish-all treat of an accomplished fact-of a magnetized needle used by all the sea-faring nations of Europe at the time to guide their ships; so that the date of the invention of the Compass (in so far as a single needle unassociated with a graduated circle and lubber's pointnothing but a needle lying in the magnetic meridiancan be called a compass) seems to be anterior to 1200 A.D.: after this, descriptions multiply, so that it would be burdensome to quote them-they merely corroborate the testimony already given.

219. The prototype of the present compass.-But now appeared a man who may be said to have devised the essential features of the compass of to-day.

Pierre de Maricourt, known in literature as Peter Peregrinus, was born in Picardy, France. In the year 1269 A.D., he wrote a letter (of which the manuscript is in the Paris Library) to a friend named Sigerus of Foucancourt; and in this, he states many things regarding the compass.

In ancient times the prevalent idea was, that the polestar governed the magnet, then' that it influenced mountains which in turn controlled the lodestone; but Peregrinus indicated the Earth as the controlling power.

Before Peregrinus' time, the needle was not in constant use aboard ship-only in cloudy weather; during the day ships steered along the land, and at night by the stars when visible.

When required, the needle was temporarily rubbed with the lodestone and floated in a bowl of water by means of a reed or piece of wood: it merely indicated the north and south line-with no fixed mark to reckon from.

Peregrinus thus describes the method of preparing the instrument:

"Take a wooden vessel, round, like a dish or platter, and put the stone in it so that the two points of the stone

may be equidistant from the edge; then put this in a larger vessel containing water, so that the stone may float like a sailor in a boat: the stone so placed will turn in its little vessel until the north pole of the stone will stand in the direction of the north pole of the heavens, and the south pole in that of the south pole of the heavens, by the will of God.”

In those days the astrolabe was in general use: it consisted of a circle graduated to degrees, provided with cross-arms, fitted with notches or sight bars: when held vertically, the cross pieces could be pointed to the horizon and to the sun and thus a rough altitude of the latter obtained.

Peregrinus combined the astrolabe with the bowl in which the needle floated, and thus produced the first instrument worthy the name of compass.

He set the magnet in a diameter of the bowl, and marked on its rim both this diameter and degree marks; the bowl was then placed in a larger vessel containing water, and a light wooden bar having an upright pin at each end, was laid on the rim of the bowl, whereby bearings could be taken.

He improved upon this by devising the pivoted compass Fips 300 and 370. [Both figures from The Intel

lectual Rise in Flectricty.]

The floating bowl and the large vessel of water are abolished, and in place of them there is the ordinary cir

cular compass-box of to-day. Its edges are marked as those of the bowl were-with the degrees of the circle.

"It is covered with a plate of glass. In the center of the instrument, and stepped in the glass cover and in the bottom of the box, is a pivot, through which passes the compass-needle, now no longer a lodestone, but a true needle of steel or iron. Then at right angles to this needle is another needle, which, curiously enough, he says is to be made of silver or copper.

"Pivoted above the glass cover is an azimuth bar, as before, with sight pins at the ends. Now, he says, you are to magnetize the needle by means of the lodestone in the usual way, so that it will point north and south; and then the azimuth bar is to be turned on its center so as to be directed toward the sun or heavenly bodies, and in this way, of course, the azimuth is easily measured." -(The Intellectual Rise in Electricity.)

Peregrinus himself says of this instrument:

"You may direct your course toward cities and islands and all other parts of the world, either on land or at sea, provided you are acquainted with the latitudes and longitudes of those places."

And little more can be added to describe the use of the highly finished instrument of to-day: in all its essential features, Peregrinus' compass of the year 1269 is the embryo of our azimuth compass. Subsequent endeavor has been chiefly in the direction of improvement of what he seems to have originated. In Peregrinus' compass, the needle is thrust through a vertical pivot, so that both needle and pivot move together: in the modern compass, the pivot is fixed, and the needle is attached to a card which oscillates on the pivot.

220. Improvement of the Compass. -Interest in the subject now flags: the essential points have been established that ships were steered by a magnetic needle at

least as early as the year 1200; that the instrument was crude and used only on occasion; and that the prototype of the present form had really its origin about the year 1269. Besides, the improvements have been wrangled over by many nations, and it would be little more than a statement of their pros and cons-a wearisome task— to treat of the additions to the first instrument. That seems to have been the work of Peregrinus; but where or when its ancestor-the simple needle floating in a bowl of water—had its origin, is not positively known; the Chinese, however, seem to have the best title to first using the needle for guiding purposes.

The compass gave a bold and confident impulse toward the open sea; and soon all nations-Spanish, English, Portuguese, Dutch, and French-undertook those long, daring, and perilous voyages that have made their seamen famous.

Ere its advent, mariners hugged the coast-ever tied to the leading-strings of Mother Earth:

Rude as their ships was navigation then;

No useful compass or meridian known

Coasting, they kept the land within their ken,

And knew no north but when the pole star shone."

-Dryden.

CHAPTER XIV.

MANUFACTURE OF THE COMPASS.

Section One: The Principles of Magnetism and Mechanics that enter into Compass Construction.

221. The Compass the Soul of the Ship.-The principles involved in compass construction will be illustrated as occasion requires by description of the compass used in the U. S. Navy; and, to save repetition, that alone is meant whenever allusion or reference is made to any one.

In unique and striking phrase, Victor Hugo has depicted the old Line-of-battle Ship, and her equipment against the forces of nature and the perils of the deep; he calls the compass the soul of this superb structure, and says of it, that against the immensity of space she has a needle!

"Un vaisseau de ligne est une des plus magnifiques rencontres qu'ait le génie de l'homme avec la piussance de la nature.

"Un vaisseau de ligne est composé à la fois de ce qu'il y a de plus lourd et de ce qu'il y a de plus léger, parce qu'il a affaire en même temps aux trois formes de la substanceau solide, au liquide, au fluide-et qu'il doit lutter contre toutes les trois. Il a onze griffes de fer pour saisir le granit au fond de la mer, et plus d'alies et plus d'antennes que la bigaille pour prendre le vent dans les nuées. Son haleine sort par ses cent-vingt canons comme par des clairons énormes, et répond fièrement à la foudre. L'ocean cherche á l'égarer dans l'effrayante similitude de ses vagues, mais le