ON NINE BALLOON ASCENTS IN 1863 AND 1864. 303 



Table X. 



In the experiments of every year there seems to be no certain difference in 

 the determinations of the temperature of the dew-point by Daniell's and 

 Regnault's hygrometers, and this temperature, determined by the use of the 

 dry- and wet-bulb thermometers, seems to be very closely approximate ia- 

 deed to the results obtained by either of these instruments, as can be seen 

 by the following comparison of results as found from aU the simultaneous 

 determinations of the temperature of the dew-point by Daniell's hygrometer 

 and the dry- and wet-bulb thermometers (free). 



The temperature of the dew-point by the dry- and wet-bulb (free) Exps. 

 up to 1000 feet was 0-1 lower than by Daniell's hygrometer, from 21. 



FromlOOO to 2000 feet was 0-1 lower than by 

 2000 to 3000 feet was 0-1 lower than by 

 3000 to 4000 feet was the same as by 

 4000 to 5000 feet was 0-4 lower than by 

 5000 to 6000 feet was 0-6 lower than by 

 6000 to 7000 feet was 0-2 lower than by 

 7000 to 8000 feet was the same as by 

 8000 to 9000 feet was 1-5 higher than by 

 9000 to 10,000 feet was 1-2 higher than by 

 10,000 to 11,000 feet was 0-3 higher than by 

 11,000 to 12,000 feet was 5-6 lower than by 

 12,000 to 13,000 feet was 0-3 higher than by 

 13,000 to 14,000 feet was 0-8 lower than by 

 14,000 to 15,000 feet was 1-0 lower than by 



from 40. 

 from 54. 

 from 60, 

 from 33, 

 from 33 

 from 34 

 from 8 

 from 

 from 

 from 

 from 

 from 

 from 

 from 



2. 

 2. 

 1. 

 3. 

 5. 

 7. 

 2. 



The number of experiments made up to the height of 7000 feet varying 

 from 21 to 60 ia each 1000 feet, as taken in the last 3 years, is sufficient to 



