and shows less erosion of the bore than either No. 1 or No. 3 experimental guns, for the same number of rounds. During the proof of the Navy guns, the average internal pressure, using thirty-five pounds hexagonal powder, the battering charge, was thirty thousand pounds per square inch. This at the surface of the cast iron bore, would only give, at the very greatest, a pressure of eleven thousand pounds per square inch or a strain a little over one third of the tensile strength of the cast-iron. It is evident from these figures and from the tests for endurance to which the experimental guns were subjected, that this system of conversion is a very strong one; also that wrought iron is a more reliable material than steel for the tube. The Army experiments have fully proved that American coiled tubes are fully equal if not superior to the English coiled tubes. More work has been obtained from the Navy 8." rifle, than from the English 8.9" ton gun, or the Army 8' rifle, firing the same charge of powder and the same weight of projectile. This is probably due to its greater length of bore. Navy 8" rifle, caliber to length of bore, 16 to 1. I. V. 1466.7 ft. Army 8" The projectiles for the 8" rifle are of two kinds; a cored, cast-iron, chilled head shot of one hundred and eighty pounds; and a long cast iron shell of one hundred and eighty pounds. The points are ogival, struck with a radius of 14 calibers. The rifle motion is imparted by means of an expansion ring. This ring-the invention of Capt. Butler, U.S. A.—is double-lipped, and either screwed or cast on a reduced portion at the base of the shot. When the charge is ignited the gas enters the annular groove between the lips, expands the outer lip uniformly all around into the rifling, while at the same time the inner lip is made to grip the shot more closely; thus insuring its receiving the proper twist and effectually preventing stripping. This expansion centers the base of the shot. The ring is purposely made sufficiently stiff so as not entirely to fill the grooves and cut off all windage. The forward end of the projectile is centered by the pressure of the gas escaping through the grooves surrounding and supporting the shot during its passage along the bore. The foregoing description has been compiled from various Army and Navy Ordnance publications at the disposal of the writer, and also much increased by valuable information kindly given by Commander F. J. Higginson, U. S. Navy. BY LIEUTENANT COMMANDER ALLAN D. BROWN, U. S. N. We who live in this latter half of the nineteenth century, and are furnished with such excellent means of navigating the trackless ocean that we are able to appoint a rendezvous for vessels in a given latitude and longitude, with the certainty of there meeting our fellow navigators, are apt to forget under what difficulties our predecessors labored less than three centuries ago. It is my design to call the attention of the Institute briefly, to the state of the Art of Navigation at the close of the sixteenth century. For my ability to do this and to thus take a hasty glance at the condition of this branch of maritime knowledge at that day, I am indebted to a rare work which has recently been placed in the Library of the Naval Academy, through the kindness of Lieutenant Colonel JAMES H. JONES, U. S. Marine Corps. This volume bears upon its title page the following: "M. BLUNDEvile. His Exercises, containing six Treatises, the titles whereof are set down in the next printed page, which Treatises are very necessary to be learned by all young gentlemen that have not been exercised in such discipline and yet are desirous to have knowledge as well in Cosmography, Astronomy and Geography as also in the Art of Navigation, in which Art it is impossible to profit without the help of these, or of such like instructions. To the furtherance of which ART OF NAVIGATION the said M. BLUNDEVILE specially wrote the said Treatises and of mere good will doth dedicate the same to all the young gentlemen of this realm. LONDON. Printed by John Windet, dwelling at the sign of the cross keys, near Paul's wharf and are there to be sold. 1594." 1 I have here as in all other cases of quotations modernized the spelling. The book is arranged somewhat like our modern Epitome of Bowditch, containing treatises upon Arithmetic, Cosmography and the use of the globes and astrolabe. In looking over the Arithmetic which, as M. Blundevile is careful to inform us, was written "for a virtuous gentlewoman and his very dear friend Elizabeth Bacou," we are at once struck with the absence of all mention of Decimal Fractions: but we do find a very elaborate description of Astronomical Fractions and many rules for the different operations to be performed upon them; these fractions, so called, were the arcs of degrees, minutes and seconds according to the sexagesimal system. We also find methods for the extraction of the square and cube roots of any number, with the following practical application of the square root. "The knowledge of finding out the square root of any number is very necessary for a Sergeant Major in the field, that he may the more readily set and arrange his squadrons of battle:" thus showing that even at that day some knowledge of Mathematics was by no means deemed amiss, in him "Who'd set a squadron in the field." Next follows a table of natural sines, tangents and secants with appropriate directions for taking out the function of any given arc, together with several applications of the uses to which these functions serve: one of the most notable of these is the finding of the distance (great circle) between two places whose latitudes and longitudes are given: this was of course simply the solution of a spherical triangle, but it was done in rather a roundabout manner. These tables were constructed by MONTE REGIO, and are credited to him by our author. Among the other uses for them, were the ascertaining of the sun's right ascension and declination having given his place in the Ecliptic, the computation of the sun's Meridian altitude, of the time of his rising and setting and the solution of various other astronomical problems, into none of which however does the question of Equation of Time enter. The table of secants is further designated as the Beneficial Table: and that of tangents as the Fruitful Table. Having thus given a brief glance at these first Mathematical principles, of which, by the way, nowhere does the author attempt the slightest explanation, our attention is next directed to the Nautical Astronomy or, as it is here called, Cosmography. This treatise has for its motto these words, which, as time goes on and astronomical research extends its domain, are found to be as true now as when first uttered by the Psalmist three thousand years ago, "The heavens declare the glory of God, and the firmanent showeth His handiwork." This is, perhaps, the most interesting portion of this quaint work, for we are here brought face to face with opinions and theories which we have been accustomed to consider as belonging to a time anterior to the date of the publication of this book. "The world is round" says the author, "by these reasons: first by comparison, for the likeness it hath to God's mind; secondly, by aptness, as well of moving as of containing; for if it were not round of shape, it should not be so apt to turn about as it continually doth, nor to contain so much as it doth, for the round figure is of the greatest capacity." And this round world "turneth like a cart wheel about a right imaginative line through the Poles, called the Axletree of the Earth." "The world is divided into two essential parts, the celestial part and the elemental part. The celestial part contains the eleven heavens or spheres, which in ascending orderly upward from the elements be these; first, the sphere of the Moon; second, the sphere of Mercury; third, the sphere of Venus; fourth, the sphere of the Sun; fifth, the sphere of Mars; sixth, the sphere of Jupiter; seventh, the sphere of Saturn; eighth, the sphere of the fixed stars commonly called the firmament; ninth, the second movable or crystal heaven; tenth, the first movable; and eleventh, the Empyreal heaven, where God and His angels do dwell. The elemental part contains the element of fire, which is next to the sphere of the Moon, and next to that, more downward, is the element of the air, and next to that is the earth, which is lowest of all." Accompanying this description is a plate with fourteen concentric circles to represent these several spheres, the earth being at the centre of revolution. This was the Ptolemaic theory which had held undisputed sway for centuries: and although Copernicus had written his treatise "de Revolutionibus" half a century before, his theory had not yet overthrown the more ancient one. Blundevile says in this connection; "Copernicus affirmed that the earth was movable, by way of supposition, and not that he thought so indeed: who affirmed that the earth turneth round and that the sun standeth still in the midst of the heavens; by help of which false supposition he hath made truer demonstrations of the motions and revolutions of the celestial spheres than ever were made before. But Ptolemy, Aristotle and all other old writers do affirm the Earth to be the center of the world, which I think few or none doubt thereof." The text next proceeds with a description of these several spheres, the eleventh or empyreal heaven being immovable: the tenth moves about the center from East to West in twenty-four hours, carrying all the others with it; while the ninth has its own proper motion as well, in a reverse direction, completing an entire revolution in thirty-six thousand years, at which time all things should be according to Plato, as they were at the beginning of the revolution; this ninth sphere also contains "the waters that be above the firmament." It is quite evident that the so called conflict between science and religion had even then begun, for the student's attention is called to the fact that "the natural philosophers allow no water to dwell above the heavens:" to which the reply is made," That is true, yet, notwithstanding, if the holy scriptures manifestly affirm that there be waters above the firmament, it behooveth a Christian man to believe it; but question perhaps may be moved what manner of waters they are that are above the firmament, whether they be such as breed rain, or whether they are only to be referred to the crystal heaven to assuage its heat, which otherwise, owing to its swift moving, would set all the heavens on fire." A note opposite this paragraph, in faded ink and in a quaint handwriting, has these words "not very good." The eighth heaven is described as containing the fixed stars, so called because "they are fastened in this heaven like knots in a knotty board:" this had the motion from East to West in twentyfour hours, common to all the remaining heavens, but it also had the motion of the ninth heaven in the opposite direction; its own proper motion was a tilting one, causing the precession of the equinoxes. The heavens of the planets, sun and moou are then noticed and the term of the revolution of each from West to East given: the same period of three hundred and sixty-five days being assigned to the Sun, Venus and Mercury. "The reason why all these several heavens seem to the eye as one entire body is, because they are all clear and transparent like fine glass or crystal through which the sight doth easily |