108 LECTURES. 



and confi<;uration have been determined, with that nicety and perfec- 

 tion which astronomical instruments and processes render possible at 

 the present day, is still comparatively small. A German geographer, 

 Mr. Doppelmayer, believed, after conscientious research, that in the 

 year 1*740 there w(re, on tlie whole globe, only 116 places the posi- 

 tion of which had been satisfactorily ascertained. In the year 1817 

 another German geographer, Mr. O'Etzel, estimated the number of 

 places on the globe the astronomical position of which had been thus 

 satisfactorily determined, at about 6,000. Of these 6,000 places 

 prol)ably two-thirds were in Europe, leaving only 2,000 for the rest 

 of the world. Although since that time the sum of observed places 

 may have been doubled or trebled, still it must be very small in com- 

 parison with the enormous number of points which ought to be known. 

 From the small number of perfectly well ascertained positions we find 

 a long series of points, ihe positions of which is pretty well known 

 from computation, from terrestrial measurement, or from astronomical 

 observations of approximate accuracy, down to those whose latitude 

 and longitude have not been fixed at all. 



The same is the case with respect to all observations other than 

 those of position ; for instance, with respect to the configuration of 

 the outlines of a bay or an island, or in regard to the soundings of a 

 harbor or bank, or to the height of hills, capes, and mountains. The 

 amount of science and activity at the present day is great, still it is 

 not omnipresent, and through the whole course of the history of 

 geography there has never been a moment in which it could be said 

 that for every jtlace all had been done that the state of knowledge at 

 the time permitted. There are many harbors in which no regular 

 soundings with improved instruments hare been made for half a cen- 

 tury or more. There are mountains the height of which, as laid 

 down in our present books and maps, is the result of observations 

 made Avith very antiquated instruments and processes. There are 

 numerous lakes or remote river sources where no scientific exploring 

 expedition has been since the time of La Condamine. 



" I sometimes find, to my surprise, in a ' very old book,' " says the 

 intelligent Bishop Kennet in the introduction to his valuable Ameri- 

 can Bibliography, "one cape or one sand-bank much more accurately 

 described than it is done in one of the newest coast pilots." The 

 same thing may be said of old maps. A chart of 1800, though upon 

 the whole antiquated, may often contain of some part of the coast, 

 which then was particularly explored, a much better representation 

 than is found in those of a later date. 



Affain, the different classes of observations laid down on one and 

 the same map are of very different value. On one survey the sound- 

 ings may be quite accurate, while, perhaps, the astronomical position 

 and the configuration of the coast is better given on a map of another 

 date. Some explorers have had particular facilities, inclination, or 

 talent for one or other of the numberless branches of geographical 

 observation, and one has thought of that which was overlooked by 

 another. The results of all these observations, from early times to 

 the present day, have been laid down partly in books and partly on 

 innumerable maps ; and nothing but a complete series of these can 



