VOL. LXVII.] PHILOSOPHICAL TRANSACTIONS. 207 



in the interpretation of nature, than a multitude of crude, careless, and im- 

 methodical experiments. But I have not done : I wished to put this matter out 

 of all doubt, and accordingly undertook another expedition to the summit of 

 Mont Saleve, on the 1 8th of September, and in a colder temperature : the ex- 

 periments then made, with their results, were as follow : 



The difference of real height was 2828.9 feet. But, a mean of 4 series 

 of barometrical observations, gives for the error on 1000 feet, 26.8. I think I 

 have now shown, that the error actually exists ; it remains that we determine 

 precisely the quantity of it. For this purpose it will be proper to collect all the 

 preceding observations in one point of view. 



Table of the Result of all the Barometrical Experiments. 



Place of observation. 



True height Height by 



trigonotnet' 



rically. 



Mont Saleve, 



At the Mole, 



Mont Saleve, 



2831.3 2775.2 

 2763.2 

 2759.4. 



4211.3 4132.7 

 4140.1 

 41 15.1 

 411 1.9 

 4113.7 

 4104.9 



2828.9 2755.6 

 2754.9 

 2748.9 

 2752.8 



Mean of all, 23.6, and the 



the barome- 

 ters. 



Mean 

 heat. 



69=.4 

 68 .5 

 67 .2 

 58 .3 



58 .9 



59 -J 



60 .0 

 60 .5 

 60 .3 



57 .5 



58 .9 

 ',9 .6 



Error in feet. 



50.1 

 68.1 

 71.9 

 78.6 

 71.2 

 96.2 

 99-4 



97.6 

 106.1 

 73.3 

 74.0 

 80.0 

 76.1 



59 .8 

 temperature 6l°.4, 



Error in i Mean error 

 1000 feet, in 1000 feet. 



-19-8 

 -24.0 

 -2.T.4 

 -18.6 

 -16.9 

 -22.8 

 -23.5 

 -23.1 

 -25.2 

 --'5.9 

 -26.2 

 -28.2 

 -26.9 



I —23.1 



I.— 21.7 



—26.8 



The Mole, from two obser- 

 vations of Mr. De Saus 

 sure, — 



The same by Mr. De Saus 

 sure, and Mr. De Luc, at 

 Geneva, — 



According to Mr. De . the Mole, 

 Luc's own obser- f ..u^ t\^\^ 

 vafons, see Re-V the Dole, 

 cherches sur I'At- ( the Buet, 

 mosphere. J M'.Blanc, 



I 



4211.3 



4883. 



4882.8 



4292.7 



8893.6 



14432.5 



4814. 



4860. 



4210. 



8770. 



14093. 



— 92. 



- 69. 



— 21.8 



-14. 



— 16.2 



The titles of the columns are sufficiently clear to make a farther explanation 

 of this table unnecessary ; and it appears, I think, incontestably, on taking a 

 mean of my 13 observations on Mont Saleve and the Mole, that this error is 

 about 23i feet on every 1000 ; that is, the rules of Mr. De Luc give the height 

 by so much too little. At the bottom of the foregoing table I have subjoined 6 

 other comparisons, some of them from Mr. De Luc's own observations, as re- 

 corded in his valuable work ; which however I must add, are certainly of less 



