§54 On Hypsometrical Measurements. [No. 4. 



Otherwise, by Table VI. 



Height corresponding to 204°.2 4123 feet 



„ 208.7 1731 „ 



Difference, or Approximate height, .. .. 2392 „ 



79° Multiplier from Table I, 1.099 



Corrected height, as before, 2628 feet. 



Col. Sykes by barometrical observations finds the height 2649 

 feet, the difference being within the limits of error of observation 



Example II. The following data are partly taken from Prof 

 Forbes's paper. — Saussure's boiling-point, 80° R. was adjusted at 

 27 French inches, or 28.777 English. At that pressure the standard 

 thermometer shewed 209°.96. De Saussure's stood therefore 2°.04 

 F. higher. Now on the top of Mont Blanc, the boiling-point was 

 187°.23 F. or reduced to the standard thermometer 185M9 F. and 

 at Geneva, 1345 feet above the sea-level, the barometer indicated 

 27.267 French, or 29.063 English inches, the mean temperature of 

 the air being about 55° F. 



in. 



Here, 29.063 log 1.463304 



T' = 185°.19 (Table V.) „ 1.234523 



Diff. of logs 0.228781 . . log 9.35942. 

 i (t + t') = 55° log A 4.80186. 



Height above Geneva 14497 ft log 4.16128. 



Geneva above the sea 1345 



Height of M. Blanc 15842 feet, 



being almost exactly the height found barometrically by Saussure, 

 and only 55 feet more than MM. Bravais and Martins's determina- 

 tion, and 59 feet higher than CorabeuPs trigonometrical measure- 

 ment. The same result may also be found otherwise, thus : — 



