198 BERTHA'S VISIT TO HER 



bers of apple-trees in this country, that it was 

 feared the making of cyder would be quite at an 

 end, if some mode of banishing those insects was 

 not discovered. Spirit of turpentine, or smearing 

 the branches with oil, were found to be useful 

 remedies : but Sir Joseph Banks has succeeded 

 completely by the more simple process of taking 

 off all the rugged old bark, and then scrubbing 

 the trunk and branches with a hard brush. My 

 uncle has found this insect infesting two of his 

 apple-trees ; so he will try each of those methods 

 as a fair experiment. 



2lst. Caroline and I took advantage of a 

 walk with my uncle this morning, to remind him 

 of his promise to teach us something of geology. 



" Are you prepared," said he, " to learn the 

 general classification ? Though uninteresting 

 till you know more, it is the necessary foundation 

 to any knowledge of that science." 



" Oh yes, we are anxious to learn it, or any 

 thing that you will be so good as to teach us." 



' c Very well," said my uncle ; " we will begin 

 at once. In examining the surface of the earth, 

 a person would at first imagine that the confused 

 variety of mineral substances he saw, was the 

 result of mere chance ; but if in different places 

 he should find the same substances constantly 

 linked together if, for instance, in traversing the 

 different coal districts, he were to find sand, clay, 



