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HOW LATITUDE IS RECKONED.
All those who have been to sea have looked on, more or less mystified, while one of the ship's officers takes his observations to find out just where the ship is. If the average landlubber is asked to tell just what happens on such occasions he will confine his explanations, as a rule, to stating that the instrument involved is a sextant, and that the sun plays an important part in the affair. After that — unless he is an exceptionally well-informed landlubber — he will trail off into vague remarks about latitude and longitude, and then, ten to one, change the subject.
But the sextant suddenly jumped into the limelight with the discovery of the pole; for, besides being indispensable to the seafarer, it is equally so to polar explorers. It is by its use alone that Peary and Cook were able to determine their whereabouts while on their weary marches through the frozen north. In fact, if they had not had the useful little instrument among their paraphernalia they would have been absolutely unable to tell whether they were at the coveted goal or hundreds of miles away from it.
Hence, this query is now more pertinent than ever: What is a sextant and what does it do?
The sextant is an instrument for measuring angles between distant objects. It consists of a frame in the form of a sector, embracing somewhat more than one-sixth (usually about one-fourth) of the whole circle; two mirrors, one wholly silvered and one silvered over half its surface, a movable arm pivoted at the center of the sector and carrying the fully silvered mirror, and a vernier, or measuring scale; an arc along the circumference of the sector , graduated into degrees, minutes and seconds and an eye-piece. Its name is derived from the Latin word sextans, signifying the sixth of a circle.
People are often puzzled to know why the sextant should be so called, when it can measure angles up to 129 degrees, or the third of a circle. But, as Lecky points out in his well-known "Wrinkles in Practical Navigation." if the possessor of a sextant will look at the arc, he will find out that by his eye alone, as a matter of fact, it consists only of the sixth part of a circle. The optical principle upon which the instrument is founded (that of double reflection) permits of half a degree of the arc being numbered and considered as a whole degree. Thus, in the sextant what is really only an arc of 60 degrees is divided into 120 equal parts, each of which does duty as a degree.
The optical principle upon which the sextant is founded is thus expressed in scientific language: "If a ray of light suffers two successive reflections in the same plane by two plane mirrors, the angle between the first and last direction of the ray is twice the angle of the mirror."
What the sextant does, expressed differently, is to solve the astronomical triangle, one point of which is the pole, the second the observed heavenly body, which is the sun, and the third the zenith, which is the point directly over the head of the observer. What the observer seeks to find out from his readings of the sextant is the sun's altitude. Once he gets that he can get all the other necessary data from the so-called "Nautical Almanac," a government publication, revised for each year, which is among the most treasured possessions of every navigator and explorer.
By latitude is meant the angular distance between the horizon and the level of the observer. In making observations at sea the actual horizon — that is, where the sky and the water meet — is used. On shore, however, observers make use of an artificial horizon. Ordinarily this consists of a cast-iron trough, containing pure mercury, which is protected from disturbances from the wind by an angular glass roof. A form of artificial horizon more suitable for the needs of explorers is that known as Capt. George's, since it is more compact and more easily carried. In place of mercury, molasses, crude oil and other substances may be used in the artificial horizon.
What is known as the "meridian altitude," or the sun's position at noon, is the best for getting the latitude, hence it is that observations are usually taken when the chronometer of the explorer or navigator tells him that it is noon. At that time the error which an observer is likely to make in determining the longitude is a matter of small importance.
The two things that an observer must know in order to get his latitude are the altitude of the sun, which he gets by means of his sextant, and the declination of the sun, which he gets from his Nautical Almanac. By declination of the sun is meant its angular distance north or south of the celestial equator — i. e., a circle reaching to the heavens which is in the same plane as the equator of the earth.
The declination of the sun is tabulated in the Nautical Almanac for noon at Greenwich, England, for each day. It varies from day to day, so that, in order to know accurately the declination of the sun at the time of taking his observations, it is necessary for the observer to know how many hours before or after noon at Greenwich the observation is taken. This is ordinarily expressed in terms of longitude east or west of Greenwich.
But at the pole there is no longitude. In spite of this the chronometer is equally necessary at the pole, in order to ascertain from the almanac the declination of the sun.
The best observer with a sextant and an artificial horizon, under ordinary conditions, would hesitate to trust his observations, to determine the sun's altitude, closer than a quarter of a nautical mile, or 15 seconds of an arc, a nautical mile being equivalent to a minute of longitude or a minute of longitude at the equator, or 6,086 feet, instead of the 5,280 feet making a statute mile. This hesitation on the observer's part is due to the fact that in making observations there are three errors likely to be made. The first is that due to lack of ability on the part of the observer himself. The second is the "instrumental error" which can practically be eliminated by using the very highest grade obtainable of instruments.
But the most serious error of all is that due to refraction.
To give an idea to the outsider of what refraction is, no better example can be adduced than the appearance of an oar in the water. Everybody will recall that it looks as if it were bent at the surface of the water. This is due to refraction. In technical language it is expressed thus: "A ray of light is bent from a straight line as it passes from one medium to another or in passing through a medium of varying density."
Thus is explained what happens in observing the sun, for the air. from a maximum density at the surface of the earth, becomes thinner and thinner as it gets higher above that surface, so that a ray of light from the sun, when it strikes the earth's atmosphere, bends and keeps bending more and more as it travels toward the earth. Tables have been prepared which give the amount in degrees, minutes and seconds of this refraction. It changes as the barometer and thermometer change and the tabulated refraction is mean or average of a large number of observations to determine what the refraction is.
The pole, by the way, is the very best point at which to take observations, for the reason that there the error due to refraction is likely to be less than at any other point on earth.
OF POLAR EXPEDITIONS.
A writer named Walter Leon Sawyer has quite interesting facts about the cost of polar expeditions. He says:
The "promoter," of the vulgar sort, he of the sordid imagination, who demands from every outlay a return of profit, has not had much to do with modern expeditions to the Arctic, though in earlier times his trail was over them all. Then, while the northwest passage to India, not the North Pole, was the goal of ambition, the discovery of such a route seeming to insure commercial supremacy, kings turned speculators and hard-headed merchants made ventures that must have figured oddly in matter-of-fact account books, Walter Leon Sawyer says in the Boston Transcript.
Yet the first polar expedition, after the interregnum that followed Norse colonization of Iceland and discovery of Greenland, was discreetly accounted for by Henry VIII, who ordered it. "For discoverie even to the North Pole, two faire ships well manned and victualled, having in them divers cunning men to seek strange regions," set out in 1527; but one was lost north of Newfoundland, and the other, having discovered nothing went home.
Sebastian Cabot, a little later, revived interest in Arctic enterprise and prompted the sending of Sir Hugh Willoughby and Richard Chancellor "for the search and discovery of the northern parts of the world, to open a way and passage to our men, for travel to new and unknown kingdoms." Willoughby died, Chancellor found Archangel and opened a trade with Russia. And, following Chancellor's success Elizabeth instigated the Muscovy company in 1575 to license Sir Martin Frobisher, who sought the northwest passage, found some mica schist which he took for gold, and wasted two subsequent voyages in gathering more. In 1580, the Company of Merchant Adventurers fitted out an expedition of two ships, one of which was lost; in 1594 and again in 1596 Willem Barentz of Holland made two attempts at the northwest passage, the latter being financed by the city of Amsterdam; and in the later years of the sixteenth century John Davys and Thomas James, Englishmen both, south the north, James being backed by the government. It was at one time "an association of English gentlemen" and at another time the Dutch East India Company that assisted Henry Hudson's ill-fated endeavors. It was King Christian IV of Denmark who sent out Jens Munk and others, Danes and Englishmen, to rediscover the lost colonies of Greenland and restore Denmark's supremacy in the Arctic.
But all these expeditions, whether financed by kings or commoners, were undertaken with commercial ends in view. Some glimmering of scientific purposes seems, however, to have lighted the voyage of the second Baron Mulgrave, who was ordered north by the British government in 1773; and thenceforward the spark of enthusiasm continued to brighten to a steady flame. Great Britain commanded or assisted or rewarded the efforts of Cook and Parry and Franklin and Ross, from 1776 to 1848. Then, as the mystery of Sir John Franklin's fate wrought on the minds of men lending a poignant interest to the problem of the Arctic, a new type of "promoter" appeared in the field — the rich man who had no selfish ends to serve. The last word of Franklin's expedition was received in 1845. Between 1847 and 1857 thirty-nine expeditions of relief and discovery were sent out, at an aggregate cost approximating $2,000,000; and, though the British government was generously active, while our own was by no means inert, a large part of the sum was provided by private individuals.
In this connection Americans naturally think first of Henry Grinnell, a native of New Bedford. In 1850 he fitted out the DeHaven search for Franklin; in 1853, together with George Peabody, bore the cost of the expedition commanded by Kane, who had accompanied DeHaven; in 1860, assisted the expedition organized by Kane's surgeon. Dr. I. I. Hayes; and in 1860, 1864 and 1871 helped to meet the expense of Hall's voyages. It is true that that was comparatively a day of small things; but the $100,000 that Mr. Grinnell devoted to Arctic exploration represented then a large fortune; and it led Dr. Kane to write the book that inspired Peary, and enabled Hall to reach the highest north attained in his day — and all this signifies that "Grinnell Land" preserves a name which is rightfully honored.
The northwestern passage, such as it is, was discovered by Sir Robert McClure or by Sir John Franklin — the reader may take his choice of authorities — in the early '50s. The magnetic pole, though "rediscovered" by Amundsen in 1905, had been located by Sir James Clark Ross in 1831. The fate of the Franklin expedition had been definitely determined by Capt. McClintock and Capt. Hall. Lacking the incentive that these problems had provided, there might have been some cessation of activity in the Arctic field, had not James Gordon Bennett of the New York Herald resolved in 1879 to conquer the pole as with the aid of Henry M. Stanley, he had just conquered Africa. Mr. Bennett was then under 40. Lieutenant Commander George W. DeLong, whom he chose, and whom the government commissioned, to command the Jeannette, was younger still; Commander DeLong had a sound theory, that of taking advantage of the polar drift, Mr. Bennett had money, both men had the enthusiasm of youth. Mr. Bennett devoted some $60,000 to the enterprise. Could the Jeannette have survived the terrible ice pressure off the New Siberian islands — it will be remembered that she made her attack from the Pacific side — one sees no reason why it should not have succeeded.
Previous to this modified co-operation with Mr. Bennett the United States government had shown no urgent interest in Arctic exploration, though, to be sure, it provided Capt. Hall with the Polaris for his third trip. But in 1881 the project of establishing international observation stations appealed to "practical" minds at Washington, and the attainment of the highest north by members of Commander Greely's party, in the following year, may have emplanted in the official bosom a feeling of willingness that this nation should continue to hold the record. Commander Peary has found no great difficulty in securing leaves of absence. For so much we have to be grateful. Meanwhile, in the last fifteen years, the Norwegian government has assisted with "real money" Nansen, gainer in his turn of the highest north, whose expedition in the Fram cost $120,000; the Italian government has speeded to a later highest north the D'Abruzzi expedition, which cost nearly $200,000; Canada, aided by England, has promoted Capt. Bernier's venture; Sweden sent out Nathorst in 1899; Denmark gave official godspeed to Amdrup in the same year; and Russia authorized Admiral Makaroff to expend on his ice-crushing ship, the Ermack, all the money that he needed.
William Ziegler of Brooklyn in 1901-2 financed the expedition led by Evelyn Briggs Baldwin and, when it failed, sent out in 1903 another expedition led by Anthony Fiala. Mr. Ziegler was a hearty whole-souled, loud-voiced, sweet-tempered man who had made a fortune in baking powder. Like every other successful business men, he knew that it is needful to spend money in order to "get returns," and he appropriated $1,000,000 to take the pole by storm. To list the supplies that were carried on the three ships of the expedition would remind the reader of a delicatessen store.
But events move swiftly sometimes, and these expeditions seem already ancient. Let us come to the present. As to Dr. Cook's sponsor, John R. Bradley, a current story pictures "the best outfit ever carried by an expedition," while another shows the explorer starving when he stumbled upon a preceding explorer's cache. Friends of Bradley, however, estimate that his outlay on the Brooklyn man's account was in the neighborhood of $15,000.
It is unfortunate for Dr. Cook that Commander Peary's adherents make so superior a showing. The chief contributor to the fund for his last voyage was Zenas Crane of Dalton. Toward the preceding voyage the late Morris K. Jesup of New York, president of the Museum of Natural History and inheritor of many other honors as well deserved, gave $50,000. Moreover believing in himself, Commander Peary "backed himself," and, on the authority of Maj. J. B. Pond, surpassed the record of any other American lecturer, speaking 168 times in ninety-six days, and thereby earning $13,000, which he devoted to his own enterprise.
Does the reader weary of large figures? It is granted that they have a repellant effect when they stand for sums that have to be given, and enthusiasts who would like to pose or to think of themselves as angels of the Arctic may well regret that they did not live in earlier and simpler days. When Capt. Hall planned his first expedition, in i860, all the actual cash he received from admirers and well wishers — who were naturally shy until he proved himself — was $980. Henry Grinnell gave $343, Augustus H. Ward of New York gave $100 and there were a few subscriptions of $50, among them one by Cyrus W. Field. Yet there were friendly souls besides who wished to aid. Capt. Hall gratefully printed a long list of such, which contributions "in kind" ranged from twenty-two pounds of hardware to a pound of tea. So, after all, it is easy to be an angel of the Arctic. One can conceive of circumstances in which, the pound of tea would be worth more to a traveler in the polar region than twenty-two pounds of hardware — or money.
Much interest must forever attach to the discovery of the compass, and especially now that the useless device has been instrumental in the discovery of the North Pole. For a period the honor of the invention was ascribed to Giola, a pilot, born at Pasitano, a small village situated near Amalfi, about the end of the thirteenth century. His claims, however, have been disputed. Much learning and labor have been bestowed upon the subject of the discovery. It has been maintained by one class that even the Phoenicians were the inventors; by another that the Greeks and Romans had a knowledge of it. Such notions, however, have been completely refuted. One passage, nevertheless, of a remarkable character occurs in the works of Cardinal de Vitty, Bishop of Ptolemais, in Syria. He went to Palestine during the fourth crusade, about the year 1204; he returned afterward to Europe, and subsequently back to the holy land, where he wrote his work entitled "Historia Orientalis," as nearly as can be determined, between the years 1215 and 1220. In chapter 91 of that work he has this singular passage: "The iron needle, after contact with the lodestone, constantly turns to the north star, which, as the axis of the firmament, remains immovable while the others revolve, and hence it is essentially necessary to those navigating on the ocean."
These words are as explicit as they are extraordinary, they state a fact and announce a use. The thing, therefore, which essentially constitutes the compass must have been known long before the birth of Giola. In addition to this fact, there is another equally fatal to his claim as the original discoverer. It is now settled beyond a doubt that the Chinese were acquainted with the compass long before the Europeans. It is certain that there are allusions to the magnetic needle in the traditionary period of Chinese history, about 2,600 years before Christ, and a still more credible account of it is found in the reign of Chingwang of the Chow dynasty, before Christ, 1114. All this however, may be granted without in the least impairing the just claims of Giola to the gratitude of mankind. The truth appears to be that the position of Giola in relation to the compass was precisely that of Watt in relation to the steam engine — the element existed; he augmented its utility. The compass used by marines in the Mediterranean during the twelfth and thirteenth centuries was a very uncertain and unsatisfactory apparatus. It consisted only of a magnetic needle floating in a vase or basin by means of two straws on a bit of cork supporting it on the surface of the water.
The compass used by the Arabians in the thirteenth century was an instrument of exactly the same description. Now the inconvenience and inefficiency of such an apparatus are obvious — the agitation of the ocean and the tossing of the vessel might render it useless in a moment. But Giola placed the magnetized needle on a pivot, which permits it to turn to all sides with facility, afterward it was attached to a card, divided into 32 points, called rose de vents, and then the box containing it was suspended in such a manner that, however the vessel might be tossed, it would always remain horizontal.