58 THE ATMOSPHERE. 



The fourth is so accurately divided as to exhibit the 

 minutest difference in elevation ; and is used for mea- 

 suring the height of mountains. 



Among these the marine barometer presents the most 

 interesting beauties. Its use, however, is not so com- 

 mon as its merits deserve. To those who wander over 

 trackless seas, and along unknown coasts, the ability to 

 discover a threatened change would be invaluable. 



Several romantic stories are connected with the his- 

 tory of this instrument ; and all who have experienced 

 its benefits, have snme incident to relate illustrating its 

 value. Arnott states that he f was one of a numerous 

 crew, who probably owed their preservation to its almost 

 miraculous warning. It was in a southern latitude. 

 The sun had just set with placid appearance, closing a 

 beautiful afternoon, and the usual mirth of the evening 

 watch was proceeding, when the captain's order came 

 to prepare with all haste for a storm. As yet, the old- 

 est sailors had not perceived even a threatening in the 

 sky, and were surprised at the extent and hurry of the 

 preparations. But the required measures were not 

 completed, when a more awful hurricane burst upon them 

 than the most experienced had ever braved. Nothing 

 could withstand it: the sails, already furled, and closely 

 bound to the yards, were riven away in tatters: even 

 the bare yards and masts were in great part disabled ; 

 and at one time the whole rigging had nearly fallen 

 by the board. Such, for a few hours, was the mingled 

 roar of the hurricane above, of the waves around, and 

 of the incessant peals of thunder, that no human voice 

 could be heard ; and amidst the general consternation, 

 even the trumpet sounded in vain. 



' In that awful night, but for the little tube of mercury 

 which had given the warning, by having fallen with 

 great rapidity, neither the strength of the noble ship, 

 nor the skill and energies of the commander, could have 

 saved one man to tell the tale.' 



The barometer is also used for determining the height 

 of mountains. It was the experiment of Pascal with 

 this instrument, that satisfactorily proved the difference 



