54° SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



the assumption of neutral equilibrium for the result will hold good 

 also when stable equilibrium exists initially in each chamber. 

 The equation of energy is now to be applied in the form 



dK+ (R) = (Q)-d(P +1) 



where (Q) replaces the latent heat of condensation. The mass 2 

 cools by expansion less than dry air, wherefore it contributes a 

 smaller portion to the —d(P + I). The difference is exactly made 

 up by the added heat (Q). It follows that the latent heat of con- 

 densation contributes nothing to the energy of the storm. The 

 available kinetic energy remains unchanged, if in the initial stage 

 we substitute dry air of the same temperature for the fictitious gas. 

 We must replace the moisture-saturated air with dry air of equal 

 density, wherefore the latter having the same pressure must have 

 a somewhat higher temperature. 



§(7) The diagram, fig. 1, is not intended to give a complete idea 

 of the phenomena in boe-en; it only contains that which we con- 

 sider as the condition for the origin of the storm. 



The length of the chamber must be measured by hundreds of 

 kilometers but the altitude by very few kilometers. It is indif- 

 ferent whether the separating surface (or screen) is initially vertical 

 or inclined, if only the wedge-shaped volume is small relative to 

 that of the whole chamber If the [inclined] boundary surface be 

 so laid that the colder mass of air 1 extends as a sharp wedge toward 

 the ground, we have everywhere steady distribution of pressure. 

 For an angle of io° between the boundary surface and the horizon 

 and for a chamber of 3000 meters altitude the length of the wedge 

 is 17 kilometers; the diminution of pressure at the ground extends 

 over this distance. If the boundary advances at the rate of 85 kilo- 

 meters per hour, then in 12 minutes the barometer at any place 

 will rise by the amount that corresponds to the difference in the 

 weights of unit columns of cold and warm air. If the length of 

 the chamber were 500 kilometers, the result would not be notably 

 different but the computation would be more troublesome. Even 

 an inclination of i° for the boundary surface with a distribution 

 of the fall of pressure over a distance of 170 kilometers would allow 

 of the existence of a great amount of available kinetic energy. 



I have as yet no definite idea as to how a condition involving the 

 presence of a great store of potential energy arises without the 

 immediate occurrence of an unloading or diminution of the poten- 

 tial by virtue of some movement of the air; in the present memoir 



