Page:On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground.pdf/16

described, those in ordinary type are interpolated from them with the help of Pouillet's exponential formula. The table has two headings, one which runs horizontally and represents the quantity of aqueous vapour (${\text{W}}$), and another that runs vertically and represents the quantity of carbonic acid (${\text{K}}$) in the atmosphere.

Table III. – The Transparency of a given Atmosphere for Heat from a body of 15° C.

H2O→ ↓CO2.	0.3.	0.5.	1.0.	1.5.	2.0.	3.0.	4.0.	6.0.	10.0.
01.0	037.20	035.00	030.70	026.90	023.90	019.30	016.00	010.70	008.90
01.2	034.70	032.70	028.60	025.10	022.20	017.80	014.70	009.70	008.00
01.5	031.50	029.60	025.90	022.60	019.90	015.90	013.00	008.40	006.90
02.0	027.00	025.30	021.90	019.10	016.70	013.10	010.50	006.60	005.30
02.5	023.50	022.00	019.00	016.60	014.40	011.00	08.70	005.30	004.20
03.0	020.10	018.80	016.30	014.20	012.30	009.30	007.40	004.20	003.30
04.0	015.80	014.70	012.70	010.80	009.30	007.10	005.60	003.10	002.00
06.0	010.90	010.20	008.70	007.30	006.30	004.80	003.70	001.90	000.93
10.0	006.60	006.10	005.20	004.30	003.50	002.40	001.80	001.00	000.26
20.0	002.90	002.50	002.20	001.80	001.50	001.00	000.75	000.39	000.07
40.0	000.88	000.81	000.67	000.56	000.46	000.32	000.24	000.12	000.02

Quite different from this dark heat is the behaviour of the heat from the sun on passing through new parts of the earth's atmosphere, The first parts of the atmosphere exert without doubt a selective absorption of some ultra-red rays, but as soon as these are extinguished the heat seems not to diminish as it traverses new quantities of the gases under discussion, This can easily be shown fer aqueous vapour with the help of Langley's actinometric observations from Mountain Camp and Lone Pine in Colorado^[1]. These observations were executed at Lone Pine from the 18th of August to the 6th of September 1882 at 7^h 15^m and 7^h 45^m a.m., at 11^h 45^m a.m., and 12^h 15^m p.m., and at 4^h 15^m and 4^h 45^m p.m. At Mountain Camp the observations were carried out from the 22nd to the 25th of August at the same times of the day, except that only one observation was performed in the morning (at 8^h 0^m). I have divided these observations into two groups for each station according to the humidity of the air. In the following little table are quoted, first the place of observation, and after this under ${\text{D}}$ the mean date of the observations (August 1882), under ${\text{W}}$ the quantity of water, under ${\text{I}}$ the radiation observed by means of the actinometer, under ${\text{I}}_{1}$, the second observation of the same quantity.

1. Langley, 'Researches on Solar Heat,' pp. 94, 98, and 177.