On the Height of Mountains, Headlands , fyc. 15 



Barometer at summit, where attach- ) 000*1 * a mo n^n 

 ed thermometer is least, j = 28635 > log. 14568.972 



For 4 uuits, from Table I, we have 1.82715 



For 5 tenths, 



.22839 



Log. corrected for temperature, 14571.02754 



Barometer at the sea =30.609, log. 14858.491 



Subtract 14571.02754 



Log. 



287.46346 =2.4585880 



From Table II, we have, 



For 6 tens, 14808] 



For 2 units, 00494 ,. e „ nn ^ 



For 2 tenths, 00049 raakin S U P for 62 " 26 ' 



For 5 hundredths, 000 12J 

 Constant, 92102 



Log. 1.07465 =0.0312671 



Hence the height in fathoms = 308.926, n log. 2.4898551 



It may be observed, that this experiment was repeated at dif- 

 ferent times, and consequently in various atmospheres, yet the 

 result never varied two feet. We may therefore conclude that 

 the highest summit of the Wicklow mountains is very nearly 

 1853 feet above the level of the sea. 



The above rule will be found to give results as accurate as 

 either that of General Roy or of Sir G. Shuckburgh, and can be 

 applied with greater ease. The investigation of this rule will be 

 given in the author's course of mathematics ; the present perform- 

 ance is too limited to enter on such an enquiry. 



General Roy makes the height in fathoms 



[10000Z=F.468d] X[l + (/-32°). 00245] ; 



Sir G. Shuckburgh 



[ L0000J=F.440rf] x [1 + (/- 32°). 00243] fathoms. 



Where l=lhe difference of the logarithms of the heights of the 

 barometer at the two stations ; d= the difference of the degrees 

 shown by Fahrenheit's thermometer, attached to the barometer; 

 fss the mean of the two temperatures shown by the detached 

 thermometer, exposed for a few minutes to the open air in the 

 shade, at the two stations. The sign minus takes place when 

 the attached thermometer is highest at the lower station, and the 

 sign plus when it is lowest at that station. 10000 (log. M — log. 



