Niagara Falls 

 1827-28 correct position of the instrument, however windy the station 



Hall , 



may be. 



The mercury stood, at two stations on the outside, at 29.68. 

 The instrument was then carried behind the Falls and placed 

 near the Termination Rock, as an impassable angle of the cliff 

 is called, which lies at the distance of 153 feet from the 

 entrance, measuring from the Canadian or western extremity of 

 the Great Horse Shoe Fall. It now stood at about 29.72. 

 The thermometer in both cases being at 70. of Fahrenheit. The 

 inner station was probably ten or twelve feet lower than the 

 external one; and it will be easily understood, that in such a 

 situation, with a torrent of water pouring over the instrument 

 and the observer, and hard squalls or gusts of wind threatening 

 to whisk the whole party into the abyss, there could be no great 

 nicety of readings. I observed, that within the Fall, the mercury 

 vibrated in the tube about four hundredths of an inch, and was 

 never perfectly steady; the highest and lowest points were there- 

 fore observed by the eye, and the mean recorded. During the 

 external observations there was only a slight tremor visible on 

 the surface of the column. In order to prevent mistakes, I 

 repeated the experiment at another spot, about 120 feet within 

 the entrance, when the mercury stood at about 29.74. though 

 still vibrating several hundredths of an inch. Upon the whole, 

 then, considering that the inner stations were lower than the 

 external one, the small difference between the external and the 

 internal readings may be ascribed to errors in observation, and not 

 to any difference in the degree of elasticity in the air without 

 and within the sheet of falling water. 



Though I was only half an hour behind the Fall, I came 

 out much exhausted, partly with the bodily exertion of main- 

 taining a secure footing while exposed to such buffeting and 

 drenching, and partly, I should suppose, from the interest belong- 

 ing to this scene, which certainly exceeds any thing I ever wit- 

 nessed before. All parts of Niagara, indeed, are on a scale 

 which baffles every attempt of the imagination to paint, and it 



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