1893.] ESSAYS. 115 



the air, — no acids were formed underneath which could attack the sur- 

 face of the rock below. Freezing moreover did not affect it. So at 

 Southbridge with this difference, that crevices here and there ad- 

 mitted the acidulated waters and, as soon as the rock was sufficiently 

 porous to admit any considerable amount, that portion underneath 

 went to powder. But on the other hand, at the south end of Wood- 

 land Street, where there were several feet of glacial deposit, strong 

 trees grew, died and were buried. The roots decayed under the soil, 

 the acids resulting devoured the clay and mica, and the quartz grains 

 became as isolated and lonely as estranged friends that never greet one 

 another. 



This is the way, too, in which chiefly the bouldei's and pebbles under 

 the surface are disintegrating and adding to the soil. If we dig them 

 out and pile them in heaps or in lines of wall, they will last next to 

 forever ; if we keep them buried deeply enough and keep something 

 growing over them, they will add to our soil and in many cases im- 

 prove the quality. I have not alluded directly to the soil as enriched 

 by organic matter. This is so well understood that I have not 

 thought it worth while to spend time upon it. But what the glaciers 

 have done for us roughly on a grand scale in some regions, we need 

 to do more in our gardens and meadows — that is we must for the 

 best results mix our soils, put lime on clay, and clay on sand, and 

 sand on the cold bogs. Coal ashes, for example, are of little imme- 

 diate value, but if mixed with clayey or gravelly soils in the propor- 

 tion of not over an eighth part, are sure to bring forth fruit in old 

 age if not earlier, and are, for fruit trees and grape-vines, specially 

 valuable fertilizers. Hypothesis and experiment are valuable in hor- 

 ticulture, but the basis after all must be what nature, God's work, 

 furnishes for us, and the processes initiated in her laboratory are 

 worthy of careful study, and are sometimes the only methods by 

 which we may profitably wrest from her bosom sustenance for man 

 and beast. 



