in the North Pacific Ocean. U. S. Hydrographic Office, 1871.

Pacific Islands, Vol. III, chapter on "Vigias." British Hydrographic Office, London, 1900.

Harriman Alaska Expedition, Vol. II, Bogoslof, our Newest Volcano, by C. Hart Merriam, New York, 1901.

Expedition to the Aleutian Islands, 1907. T. A. Jaggar, Jr., in The Technology Review, 1907, Boston.

Recent Changes in Level in the Yakutat Bay Region, Alaska, by R. S. Tarr and Lawrence Martin, in Bulletin of the American Geological Society, 1906.

An Index to the Islands of the Pacific Ocean. W. T. Brigham, Honolulu, 1900.

Geography, articles by C. R. Markham, A. R. Clarke, and H. R. Mill in Encyclopædia Britannica.

Development in Dimensions of vessels, Elmer L. Corthell, Tenth International Navigation Congress, 1905.

NAUTICAL CHARTS

CHARTS AND MAPS

Need of maps. Maps are useful and necessary for many purposes. Only by means of a correct map or globe can a clear idea of the geography of a region be given. An attempt to convey the same information by a written description would in comparison be both cumbersome and obscure. Even by passing over an extensive region a man unaided by instruments will obtain only a rather crude notion of the relations, which he could clearly see on a good map. The importance among the human arts of the making of maps is indicated by the references to them in very early historical records, and by the skill in map drawing shown by some of the primitive peoples of to-day. This skill exists particularly among races whose mode of life gives them a wide horizon, as for instance the Eskimos. An interesting instance of this was the case of Joe, an Eskimo guide, who, in 1898, before the surveys of the Yukon delta were made, drew a map of the Yukon mouths with much more complete information than any previously available.

Without attempting to enumerate in detail the special uses for maps, in the broader sense they may be said to be essential for commercial, engineering, military, scientific, educational, and political purposes.

Early geography and map making. The oldest map known is a plan of gold mines in Nubia, drawn on a papyrus. This is of the thirteenth century B.C., and was found in Egypt.

In the earliest historic times men believed the earth to be a flat surface of nearly circular outline, a natural inference for those with limited outlook and communication. Later the idea was introduced of the ocean as a river bounding the earth disk. The spherical theory of the earth was, however, early accepted by learned men, and was demonstrated by Aristotle (384 to 322 B.C.), who used as proofs the earth's shadow on the moon, and the change in the visibility of the stars in traveling north or south. Crates constructed a terrestrial globe in the second century B.C.

There is no Greek or Latin map extant of earlier date than the time of Ptolemy, but there are references showing that maps were in use. One of the first of such passages in Greek literature is the interesting comment of Herodotus written in the fifth century B.C., "but I laugh when I see many who already have drawn the circuits of the earth, without any right understanding thereof. Thus they draw Oceanus flowing round the earth, which is circular, as though turned by a lathe, and they make Asia equal to Europe."

A map of the world was drawn by Anaximander, 560 B.C. A hundred years later Democritus drew a map having an oblong shape, and taught that the width of the world from east to west was one and a half times its extent from north to south, a conclusion based on his travels eastward as far as India. This theory, which was for a time accepted, has left an enduring mark in the words longitude and latitude, originally signifying the length and the breadth of the earth.

The first application of astronomy to geography was made by Pytheas, who about 326 B.C. obtained the latitude of Marseilles by an observation of the altitude of the sun. Dicearchus in 310 B.C. determined the first parallel of latitude by noting places where on the same day the sun cast shadows of equal length from pillars of equal height. Eratosthenes (276 to 196 B.C.) was the first to compute the circumference of the earth from observations of the altitude of the sun at Alexandria and at Syene in Upper Egypt and an estimation of the distance between these two places. Ptolemy, a Greek of Alexandria, in the years from 127 to 151 A.D. wrote extensively on geographic subjects, and collected into systematic form all geographic knowledge then existing; he was the greatest geographer of early history.

In the ten centuries which followed, part of the early advance in this science was obscured, and the theory that the earth was a flat disk surrounded by the sea again became prevalent. The voyages of discovery of the middle ages, however, led to a rapid development of geographic knowledge.

The flattening of the spherical earth was not suspected until in 1672 a clock regulated to beat seconds at Paris, when taken to Cayenne near the equator was found to lose two and one-half minutes a day. Newton proved that this was due to the fact that the earth is an oblate spheroid. In 1735 accurate measurements were undertaken to determine the size and shape of the earth. The equatorial diameter has been found to be 7926.6 miles and the polar diameter 7899.6 miles, the difference, or 27 statute miles, being the amount of the flattening at the poles.

The first sailing directions. The early Greek and Roman writers do not allude to charts or maps intended especially for the use of seafarers. There are, however, extant several peripli or descriptions of the coast. Some of these appear certainly to have been intended for use as nautical guides, corresponding to the modern sailing directions. It is probable that they were explanatory of or accompanied by coast charts, now lost. They are of interest therefore as being probably the first compilations for the guidance of seamen. One of the earliest, written apparently in the fifth and fourth centuries B.C., is entitled "Scylax of Caryanda, his circumnavigation of the sea of the inhabited part of Europe and Asia and Libya." It contains a systematic description of the coasts of the Mediterranean, Black Sea, and part of the west coast of Africa. The following are some extracts which indicate the character of the work. It is to be noted that no bearings are given, and that distances are usually stated by day's sail: Africa is referred to as Libya.

"Europe. I shall begin from the Pillars of Hercules in Europe and continue to the Pillars of Hercules in Libya, and as far as the land of the great Ethiopians. The Pillars of Hercules are opposite each other, and are distant from each other by one day's sail.... From Thonis the voyage to Pharos, a desert island (good harborage but no drinking water), is 150 stadia. In Pharos are many harbors. But ships water at the Marian mere, for it is drinkable.... From Chersonesus is one day's sail; but from Naustathmus to the harbor of Cyrene, 100 stadia. But from the harbor to Cyrene, 80 stadia; for Cyrene is inland. These harbors are always fit for putting into. And there are other refuges at little islands, and anchorages and many beaches, in the district between.... After the isthmus is Carthage, a city of the Phœnicians, and a harbor.