Improvement of the Barometer. 103 



inventive genius, combined an untiring zeal for knowledge. He trav- 

 elled extensively, and it was during his passage over the Alps, where 

 from the blue color of the heavens, an idea occurred to him of con- 

 structing an instrument, with degrees and altitudes marked to each of 

 the blue shades, which should correspond to those in the heavens."" 

 And, continued this sage philosopher, " Saussure is dead, and those 

 only who have been at great heights, and retain a recollection of the 

 color, are capable of making a cyanometer." 



With the information I derived from him and my subsequent ex- 

 perience of these colors, I constructed such an instrument ; and after 

 repeated trials, comparing it with the barometer, at various altitudes, 

 I found it could not be relied on for accuracy. 



Many men who have devoted their attention to the subject, I be- 

 lieve, are convinced that both the cold and darkness increase as we re- 

 cede from the earth ; and I have no hesitation in saying, that beyond 

 the earth's atmosphere, it is as much darker than night as any thing 

 we can conceive ; and although this darkness may increase in reg- 

 ular progression from the earth, still from causes before related, I do 

 not believe that any instrument can be found, as a substitute for the 

 barometer, in measuring high altitudes. 



At my fifth ascent with a balloon, from New York, in May, 1833, 

 I was compelled, in consequence of a high wind which prevailed, to 

 unmoor without any philosophical instruments, except the cyanome- 

 ter, which I had fortunately placed in my pocket book. From caus- 

 es which were stated in the public journals, the balloon was uncon- 

 trollable for some minutes, (a part of which time, it was ascending 

 with nearly the rapidity of an arrow,) although immediately on leav- 

 ing the earth, I opened the valve, which is near the top, and through 

 which the gas would soon have escaped, but for the rapid upward 

 motion, which caused so much resistance or pressure from the atmos- 

 phere, as to retard the escape of the gas, until thirty or forty min- 

 utes, when the aerostat was poised in air, and I had reached a great- 

 er altitude than I have before or since attained. Here for the last 

 time, I tried the cyanometer, which for any utility, I might as well 

 have left below with the barometer. The heavens were many 

 shades darker than the blue tints to which I had affixed an approxi- 

 mate degree and altitude on my cyanometer, and so uncertain is 

 sight, that when I had selected a corresponding shade on the cyan- 

 ometer, in one instant the heavens would appear too light and the 

 next moment too dark. I resolved then to abandon all further ex- 



