2i!4 pr()(i:ki)in(;s of tiik academy of [1800. 



all his iiieasureinents except those made from Port Mulgrave, giving 

 them " no weight in the result, as they were all taken at great dis- 

 tances from the peak, and subject to various disturbing influences 

 and uncertainty in most of the positions (p. 164)." And yet it is up- 

 on the accurate determination of the position "At Sea," 127 miles 

 distant, that " the position of Mount Saint Elias depends" (p. 165); and 

 necessarily upon the determination of this position must also depend 

 the accuracy of the measurement of height. Malespina's measure- 

 ment was made from a point apparently very close to that occupied 

 by the Coast Survey Officers, and his results, as has already been 

 seen, vary negatively by 1600 feet ; but he estimated the distance 

 separating him from the mountain at 55.1 nautical miles. Mr. 

 Dall remarks, in relation to the discrepancy existing between the 

 two measurements, that the doubt lies wholly with the distance. 

 But this does not explain the great range in Mr. Dall's own results. 

 And we are perhaps led to be the more suspicious regarding the 

 value of these when we take into account the discrepancies which 

 appear in the determination of the altitude of Mount Fairweather. 

 Three series of sextant observations were made of this mountain 

 from the region about Lituya Bay and Cape Spencer, with the result 

 of obtaining an average value of 15,447 feet. Vertical circle 

 measurements of the same mountain made from Port Mulgrave in- 

 dicate 15,270 feet, while the average of all measurements is 15,423 

 feet. Mr. Dall calls attention to the close correspondence of these 

 results, and comments more particularly upon the " unanimity in the 

 Lituya Bay observations." ^ A reference to the exact results obtained, 

 without recourse to the delusive system of extracting averages, shows, 

 however, that in place of unanimity we have the reverse. Thus, the 

 sextant observations taken from "Off Cape Spencer" indicate 16,- 

 009 feet, those from "Off Lituya Bay" 15,247 feet, and those from 

 " Off Lituya " 15,085 feet {op. cit. p. 174) a difference in extremes of 

 upward of 900 feet. This divergence in the measurement of a 

 mountain three miles ( =b ) in height from positions 20-50 miles dis- 

 tant makes very doubtful the results obtained in the case of St. Elias, 

 where the distances were still very much greater, and the angles of 

 observation correspondingly smaller. 



In view of the broad divergence existing in these later measure- 

 ments, and the fact that all earlier determinations give less than 

 18,000 feet for the height of Mount St. Elias, geographers will prob- 



1 Including liere the measurements made off Cape Spencer. 



