102 THE POPULAR SCIENCE MONTHLY. 



without hardly knowing what is the matter with them, who 

 would be all the better for trying whether their discomforts 

 spring from too high and rich a diet or from the inability to pro- 

 cure any but inferior meat, or fish. In the first case they would 

 soon feel their tired digestions rested and their irritated nerves 

 calming down, while in the latter they would find out that it is 

 easy to get a healthier and an equally satisfying meal for half the 

 cost of what they were in the habit of spending before. 



Though these motives are not perhaps the highest which 

 ought to lead us to a result, they are those which exercise a most 

 general influence. The small number who change their mode of 

 life from principle only know how far above bodily health the 

 blessings are which grow out of the sacrifice. Before the eyes of 

 everybody the lines of the Latin poet must conjure up a delight- 

 ful and attractive picture : 



" Forbear, O mortals, to taint your bodies with forbidden food ; 

 Corn have we ; the boughs bend under a load of fruit ; 

 Onr vines abound in swelling grapes; our fields with wholesome herbs, 

 "Whereof those of a cruder kind may be softened and mellowed by fire. 

 Nor is milk denied us, nor hofiey smelling of the fragrant thyme ; 

 Earth is lavish of her riches, and teems with kindly stores. 

 Providing without slaughter or bloodshed for all manner of delights." 



ORIGIN OF THE MISSISSIPPI VALLEY RAINFALL. 



By J. IIAERIS PATTON, Ph. D. 



IT has been assumed that the evaporation off the Gulf of Mexico 

 furnishes the most part of the rainfall of the great valley. 

 Says an authority, when speaking of that of the whole country, 

 " By far the greater portion comes from the gulf and spreads over 

 the central and eastern part of the Mississippi Valley, and even 

 much of the Atlantic slope." Let us examine the data on which 

 this statement is based. The area of the Mississippi Valley is 

 estimated at 1,244,000 square miles, and the annual average rain- 

 fall on its surface is forty-two inches that is, if the rain water 

 did not penetrate the earth, run ofi", or evaporate, at the end of 

 the year the depth would be three feet and a half. 



The area of the Gulf of Mexico is estimated to be one fourth 

 that of the valley. It is easily shown by mathematical calculation 

 that it would require an annual evaporation off this area of four- 

 teen feet to furnish the required rainfall, even if all the water thus 

 raised into the atmosphere were utilized. Again, the area of the 

 gulf is swept by the extreme right flank of the trade winds. 

 These winds must carry toward the west a large portion of the 



