which causes the Stellar Radiations. 217 



diffusion is annihilated, and the same original amount of heat 

 is reproduced. By a thermometer in the receiver of an air- 

 pump the loss of heat by expansion is seen clearly enough ; 

 but in the sinking of an oil-well recently in North-western 

 Pennsylvania it was manifest on a magnificent scale. Instead 

 of striking a reservoir of oil, the auger entered an accumula- 

 tion of gas (a hydrocarbon) ; and as this gas expanded on 

 issuing with amazing force from the orifice of the well, its own 

 heat was converted into repulsion, and it absorbed the heat 

 from the surrounding atmosphere and from the ground. The 

 watery vapour in the gas and in the air fell down as snow, and 

 the ground all around was frozen : it was like the freezing of 

 carbonic acid by its own expansion. 



From the well-ascertained fact that a gaseous diffusion ab- 

 sorbs 144° F. of heat by every increase of its original volume, 

 which heat is converted into the form of repulsion, and is called 

 latent heat, we are enabled to calculate the amount of latent 

 heat in all the higher strata of our atmosphere. A volume of 

 air rising three and a half miles (more accurately 3'43 miles) 

 becomes two volumes, and contains 144° of latent heat ; on 

 rising double that distance (6*86 miles) it becomes 4 volumes ; 

 therefore 3 new. volumes are added, and it contains 432° of 

 latent heat ; at 1029 miles it becomes 8 volumes, and 7 new 

 volumes are added, and therefore it contains 1008° of latent 

 heat ; and so on upward, according to the following Table (p. 

 218), which (with other columns here omitted) was constructed 

 by Mr. Benjamin V. Marsh, merchant and, like Benjamin Frank- 

 lin, an amateur of science in Philadelphia. It first appeared 

 in the ( American Journal of Science,' July 1853. His paper 

 on many accounts is valuable ; and the subject is further car- 

 ried out in my own paper on Meteors in the Proceedings of 

 the American Association for the Advancement of Science for 

 1871. 



The appearance of meteors is a proof that our atmosphere 

 extends upwards more than 200 miles, and that its loftier 

 regions are wonderfully charged with latent heat. In my 

 paper on Meteors I gave two instances, one in Europe and the 

 other in America, where meteors travelled more than a thou- 

 sand miles through the air from 40 to 100 miles high, and 

 continued vividly bright through the whole distance until they 

 passed from view. Last year another passed in the same in- 

 candescent manner a thousand continuous miles over the 

 United States. I also gave other instances of vertical descents, 

 when invariably the light of the meteors went out before reach- 

 ing the ground. They prove that in these cases the very bright 

 light comes, not from the meteor itself, but from the air in its 



