430 



TRANSACTIONS OF SECTION iS. 



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 degree of dependence, could not be considered as anything but 

 approximate. Some parts of the eastern States are, as you see, shaded with a 

 tint of the second density, but, with this exfception, such mapping as had been 

 done either in North or South America cannot be considered of a higher order 

 than route-traversing and sketching, and is tinted accordingly. 



Vast areas of Central Asia, and a still larger portion of the interior of Africa, 

 were entirely unmapped in 1860, as was also the case with South America away 

 from the courses of the great rivers, North America and the Arctic regions. 

 Attempts had been made to penetrate and traverse the desert-like interior of 

 Australia, but to a great extent this region was still entirely unmapped. Several 

 important expeditions had commenced the exploration and mapping of the coast- 

 line of the Antarctic continent, such as that of Captain James Ross, who had 

 penetrated a considerable distance south in the neighbourhood of South Victoria 

 Land, Captain Wilkes and others, who had eighted land to the we.^t of this 

 region. But, after all, little had been done in the way of surveying and mapping 

 in the Antarctic regions. 



Referring now to the 1916 map on which the same shades of tints have the 

 same meaning as on the previous map, you will see at once that the parts that 

 are accurately surveyed from a topographical point of view, based upon triangu- 

 lation or rigorous traverses, have greatly increased in extent, and these now 

 represent, according to a rough estimate I have made, 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. Remarkable progress has also been made with regard to both 

 of the less accurate kinds of surveying and mapping, while the parts that are 

 now entirely unsurveyed and umnapped only amount to about one-seventh instead 

 of a little over one-half, which was roughly the amount in 1860. 



I have attempted to form an estimate of the condition of the world's surveys 

 as represented by the differently tinted areas on the maps for 1860 and 1916 ; 

 and, taking the total area of the land-surface of the earth together with the 

 unknown parts of the Arctic and Antarctic regions which niav be either land 

 or water, to be 60,000,000 square miles, I have obtained the following results : — • 



1916 



Sq. Stat. Proportion 

 Miles to Whole 



1860 



Sq. Stat. Proportion 

 Miles to Whole 



1. Mapped from accurate topo- 



graphical surveys based on 

 triangulation or rigorous 

 traverses 



2. Mapped from less reliable 



surveys, chiefly non-topo- 

 graphical 



3. Mapped from route traverses 



and sketches 



1,957,755 = 0-0326 

 or roughly ^ 



2,017,641 = 0-0336 

 or roughly J^ 



25,024,360 = 0-4170 

 or roughly § 



4. Entirely unsurveyed 

 unmapped 



aud\ 30,997,054 = 0-5166 

 J or just over | 



8,897,238 = 0-1482 

 or roughly | 



5,178,008 = 0-0806 

 or just over jtj 



37,550,552 = 6258 

 or little less than f 



8,350,794 = 0-1391 

 or little le.ss than 1 



These proportions can perhaps be more clearly seen from the following 

 diagram (Plate II.), on which numbers and tintings have the same significance 

 as on the maps and table. 



From the figures here given it is plain that with the same rate of progress 

 as that of the past sixty years or so it would take just over four hundred years 

 more to complete the accurate trigonometrical surveying and topographical 

 mapping of the earth's land-surface, including the parts of the Polar regions 

 that may possibly be land — ^that is, the 60,000,000 square miles which we have 

 taken for this total area ; but this will certainly not be the case, since the rale 

 at which such surveys have been carried out has been greatly accelerated during 

 recent years, owing to the rapidly increasing demands for accurate topographical 

 maps, improvements in methods, and other causes, so that it will possibly not 



