304 ' SCIENTIFIC RECORD FOR 1834 



10,000 parts of air, wliicb is somewhat smaller than has been found for 

 France and the summits of mountains in France, so that they conclude 

 that the general mean value of the carbonic acid in the whole atmos- 

 phere is somewhat smaller than had hitherto been assumed from obser- 

 vations in Europe. [Z. 0. G. M., xviii, p. 473.) 



165. Miintz and Aubin have studied the observations made by the 

 French International Expedition to Cape Horn with reference to the 

 quantity of carbonic gas in the air. They desired to test the theory of 

 Schlossing, according to which there should be less CO2 in the southern 

 hemisphere because of its absorption by the cold ocean water. The re- 

 sults of the observations which were made by Dr. Hyades have con- 

 vinced Miintz and Aubin that the mean value 2.56 in 10,000 for the 

 southern hemisphere, as compared with 2.84 for the northern hemisphere, 

 confirms Schlossing's theory. They also find that the mean of the meas- 

 ures taken at night-time is slightly less than the average for the day- 

 time, which agrees with the theory requiring the colder waters to absorb 

 more of the gas. This view is confirmed by grouping the measurements 

 according to the observed temperature, from which they find the aver- 

 age 2.5.30 parts of CO^j for temperatures lower than 5°, and 2..")98 for 

 temperatures above 5°. {Z. O. G. M., xix, p. 462.) 



166. A. Woeikof remarks upon some desultory observations of Pro- 

 fessor Tyndall that these do not demonstrate the transparency of 

 dry air to radiant heat; on the other hand, his exposed thermome- 

 ters over the snow must have fallen into a lower temperature, because 

 the snow itself possesses a great radiating power, and is, moreover, a 

 poor conductor. That aqueous vapor must exert some influence on the 

 absorption of radiation will be admitted by all; the opponents of Pro- 

 fessor Tyndall for these many years past have simply affirmed that its 

 influence is by no means so large as Tyndall claims. {Z. 0. G. j1/., 

 XVIII, p. 275.) 



167. A. Woeikof also shows that Tvndall's views are inconsistent with 

 well-established meteorological facts in dry climates. {Nature, xxvii, 

 p. 400.) 



168. J. ]\I. Pernter comments on Professor Tyndall's recent renewal 

 of his conviction as to the extreme efficacy of aqueous vapor in absorb- 

 ing radiant heat, and makes the following ijoints: 



1. Langley's measurements and Abney's demonstration that the vapor 

 in the atmosphere does not exert upon the dark heat rays the absorbing 

 power that Tyndall thinks, that on the contrary the bright part of the 

 spectrum experiences the greatest absorption. Abney's, Festing's, and 

 Becquerel's photographs of the solar spectrum give the direct demon- 

 stration that it is fluid and not gaseous water that exert a sensible 

 absorption on the ultra-red. 



2. Tyndall's idea that the aqueous vapor prevents loss of heat by 

 radiation from the earth's surface is completely answered by other 

 explanations of the same phenomena. 



3. With reference to the elegant experiment of Tyndall's with the 



