23d January, A. D. 1896. 



ESSAY 



BY 



Dr. THOMAS C. MENDENHALL, Worcester, Mass. 

 Theme: — What We Don't Know About the Weather. 



Meteorology is the oldest of the sciences. Weather phenomena 

 were noted by the ancients, as correct predictions were of advantage 

 to them in hunting and fishing. 



The study of the weather antedates the science of astronomy, which 

 is popularly thought to be the oldest of the sciences. Weather calcu- 

 lation is the most imperfect of the sciences, if indeed it can be con- 

 sidered a science at all. This is due to the difllculties of the prob- 

 lems confronting those who deal with the study. There are but few 

 principles underlying the subject. 



The earth's core is in an intensely heated condition. For example 

 we will compare the earth to a globe eight inches in diameter, one 

 inch corresponding to each one thousand miles of the earth's thick- 

 ness. If we should penetrate fifty miles into the earth's surface we 

 should find it in a heated condition or in a fused state. This would 

 mean one-twentieth of an inch of our globe's thickness. Notwith- 

 standing the great mass of heated matter within the earth we receive 

 practically no heat from this source. This is due to the fact that the 

 earth is such a poor conductor of heat. Solar heat is what we have to 

 deal with in our weather phenomena. 



Mars, the nearest of our planet neighbors, probably has no atmos- 

 phere, and the inhabitants have to content themselves with some 

 other topic of conversation than the weather. 



The air on the surface of the earth is commonly said to extend 

 forty-five or fifty miles into space. In fact it extends much farther, 

 but in a greatly rarefied condition. The fact of its existence at such 

 a distance is proved by meteors, which acquire an intense heat by 



