PROFESSOR OLMSTED'S OBJECTIONS. 451 



into the air below the line of perpetual congelation, to have 

 condensed vapor less than one seventh of its weight. This 

 will easily be perceived by comparing the relative latent 

 heats of vapor and of water, and this, too, even if it re- 

 ceived no heat from the warm air into which it fell. But 

 even if the original nucleus were of the temperature of the 

 interplanetary spaces, 57 or 58 below zero, it would not 

 increase one fifth in size by condensing on itself the vapor, 

 before it would be entirely melted by the disengaged latent 

 caloric. 



Professor Olmsted concludes his essay by saying that the 

 momentum of a hail stone would be one hundred times 

 greater if it did not, at every stage of its progress down to 

 the very ground, receive new accessions of watery vapor, 

 which, being matter at rest, is to be put in motion by the 

 falling body, and consequently its speed is continally re- 

 tarded. But he must now perceive, from what has already 

 been said, that the velocity of descent will not be dimin- 

 ished one fifth, even when the stone has condensed upon 

 itself vapor enough to melt it. 



Before I take leave of this extension of Hutton's theory, 

 I must notice another remark of Professor Olmsted, which, 

 if correct, would of itself prove fatal to the theory which I 

 have advanced. He says : " We have certain evidence 

 from the concourse of opposite winds, and from the density 

 and consequent blackness of the clouds, that a great con- 

 densation takes place in the region of the storm." Now, 

 it appears to me that it would be much easier to account 

 for the concourse of winds, by supposing a rarefaction in 

 the region of the storm, just as a rarefaction in a chimney 

 is the cause of the air in the room moving towards the fire- 

 place. This, to my mind, is an elementary principle ; and 

 no authority, however great, could have the least influence 

 in changing my view of it. From the following extracts, 

 however, it would appear that Professor Olmsted has the 



