Page:The Scientific Monthly vol. 3.djvu/525

 TEE PROORESS OF SCIENCE

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��Europe, where a considerable extent of aceurate survejing had been carried out, the onlj country where any map- ping, based upon triangulation, had been done was India. These areas are shown in the darkest shading. In Europe, France, British Isles, Germany, Austria, Italy, Bussia, Switzerland, Denmark, the Netherlands, and Scandinavia had already made a good conunencement with their government maps based upon trigonometrical surveys, but these were in several cases by no means complete. India has been noted for the excellency of its surveys ever since the days of Major Lambton, who started the work in 1804, and Colonel Everest, who suc- ceeded him as head of the surveys after Lambton 's death in 1823.

In the parts of the Eastern Hemi- sphere that were surveyed and mapped in the second degree of accuracy, that is, those shown by the next tint, may be included most of the remaining parts of Europe, Egypt, and parts of Algeria near the coast. For the rest such map- ping as was done was based upon rough route-sketches, shown by the third tint. In this must be included practically all that was known of the African conti- nent, such as the explorations of Mungo Park, Beke, Livingstone, Speke and Grant, and others, as well as the early exploratory surveys in Central Asia and Australia. The regions that were en- tirely unsurveyed and unmapped at this time were enormous in their extent, and included not only the Polar regions, but vast areas of Central Africa, Asia and Australia.

Turning to the Western Hemisphere,

��we find that at this date no triangola- tion of any extent had been carried out. The U. S. Coast and Geodetic Survey had made a good start, but their work had been confined to the coastline or districts near the coast. There had been La Condamine's attempt at measuring an arc of the meridian near Quito in South America in 1736, the measure- ment of the Mason and Dixon line, and their survey of the boundary between Pennsylvania and Maryland, in the latter part of the same century; but neither of these resulted in any serious topographical mapping. Such surveys as existed of the interior parts of the United States in 1860, although they varied as regards their merits and de- gree of dependence, could not be con- sidered as anything but approximate. Some parts of the eastern states are shaded with a tint of the second density, but, with this exception, such mapping as had been done either in North or South America can not be considered of a higher order than route-traversing and sketching, and is tinted accordingly. Beferring now to the 1916 map on which the same shades of tints have the same meaning as on the previous map, the parts that are accurately surveyed from a topographical point of view, based upon triangulation or rigorous traverses, have greatly increased in ex- tent, and these now represent about one seventh of the total area of the land- surface of the earth, instead of only one thirtieth, as was the case in 1860. Be- markable progress has also been made with regard to both of the less accurate kinds of surveying and mapping, while

��isso

Sq. Stat. Proportion MlleB to Whole

Mapped from accurate topographican 1957755^0.0326 surveys based on triangulation or rigorous traverses

��or roughly 1/30

��Mapped from less reliable surveys,^ 2,017,641 = 0.0336 chiefly non-topographical j or roughly 1/30

Mapped from route traverses and\ 25,024,360 = 0.4170 sketches J or roughly 2/5

« . ., , , , ^ 30,997,054 = 0.5166

Entirely unsurveyed and unmapped >- .', ,«

'^'^ J or just over 1/2

��1916

8q. Stat. Proportion

MlleB to VITliole

8,897,238 = 0.1482 or roughly 1/7

5,178,008 = 0.0866 or just over 1/12

37,550,552 = 0.6258 or little less than 2/3

8,350,794 = 0.1391 or little less than 1/7

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