~ Mountains in Neio York. 87 



tioned. It is granted that it is possible he may be after all nearest 

 the truth, but so long as the evidence in the case is more against 

 than for such a conclusion, his claim to svperior accuracy cannot 

 be allowed. Capt. Partridge has had perhaps more experience 

 than any other individual in the United States in rncasnriu 

 mountain elevations with the barometer. la two measurements 

 made by him of Mt. Washington in New Hampshire, the first 

 gave 6,103 feet and the second 6,234 feet. The measurement 

 of the same mountains by Prof Bigelow, as computed by Prof. 

 Farrar of Cambridge, gave as the height above tide 6,225 feet, 



a coincidence somewhat remarkable, considering the very -^reat 

 elevation of Mt. Washington. 



Mr. Emmons states that the distance from Mt. Marcy to White- 

 face is about 16 miles, and that the depression of the latter from 

 the former is 15 minntes of a degree. If the instrument used by 

 Mr. Emmons in taking this angular depression was a suitable one 

 and in a proper state of adjustment, and if he is correct as to the 

 distance, the difference in elevation of those two summits would 

 have been obtained therefrom with more accuracy than from the 

 barometrical measurements. No one capable of appreciating all 

 the causes of error in the two modes of measurement would prob- 

 ably deny this. Assuming, therefore, the data above given as 

 correct, of which I cannot but express some doubt, it gives a dif- 

 ference in elevation of the two peaks of 578 feet, nearly, whereas 

 the difference shown by Mr. Emmons's barometrical measure- 

 ments is 739 feet, or nearly 30 per cent, greater, being nearly as 

 much greater as the result by my measurement is less^ showing 

 that, if the 578 feet is taken as the standard^ there is about as near 

 an approximation to the truth in the one case as in the other. 



The barometer I consider a very valuable instrument, and have 

 made much use of it, as being a cheap and expeditious mode of 

 arriving at an approximate knowledge of the general features of a 

 country; but that it will afford, by a single observation, in the 

 hands of practiced or unpracticed observers, and under all circum- 

 stances, results as much to be depended on for their accuracy as 

 would be inferred from Mr. Emmons's statement, cannot be con- 

 ceded. 



The principal sources of error in the use of this instrument are 

 its great liability, particularly the mountain barometer to get out 

 of repair. The difficulty also of arriving at a correct knowledge 

 of the change of pressure; or condition of the atmospheric column 



