ON THE CAUSE OF RINGSHAKE IN TREES. 195 



have a share. How do you think so ? Because you observe a 

 considerable quantity of surface water here, and our pits are 

 covered in the bottom with it already ; and in this case severe 

 frosts, if of long continuance, may have penetrated to the very 

 centre of the tree, and if a strong gale of wind should have 

 occurred at the same time, I have no doubt the wind acting 

 upon it caused the shakes we now see at the butt end. Then 

 you do not attribute the result so much to the soil as to the wet 

 state of the ground, a severe frost, and high winds ? Ko, I do 

 not ; and from the appearance of the tree, I fancy it has had a 

 few heavy limbs on it, which would catch a considerable force 

 of the wind, producing a bad twist upon the stem, and this 

 occurring when the tree was very rigid, was the cause, without 

 doubt. ISTow, then, suppose we search for more ringshaken 

 trees, and see if your argument holds good in every case. I do 

 not mean to assert that it does so, because, I believe, ringshake 

 is not produced in every case from the same cause. Here is 

 one, then, growing upon bare, rocky soil, with not more than 

 three inches of light mossy loam on the top of the rock ; being 

 on the top of this knoll, water could have little, if any, effect 

 here. The rock seems very smooth on some parts of it, but 

 must have some crevices in which the roots have got a hold, 

 otherwise the tree would have been blown down. There must 

 be some crevices, as you say. Here is a large root firmly fixed 

 to the rock, and there is the same on the opposite or west side 

 — the roots are mostly small on the north and south sides. The 

 top and the roots of the trees have both to be taken into 

 account here ; why so ? Because you can easily perceive that 

 heavy limbs have been growing upon this tree ; the stem, though 

 pretty long, is not very thick for its age, and the heavy limbs 

 being acted upon by the wind, would cause a severe stress upon 

 these main roots growing on the east and west sides of the root, 

 and you see quite plainly that the largest splits in the trunk 

 are direct across the stem — or north and south in the stool ; 

 this is the place where the action of the wind would rest most 

 severely. Why do you think so ? Because the rock is much 

 sloped, and the roots on the north and south sides having very 

 little hold of it, the resistive stress of the wind would fall to be 

 borne by the principal ones on the east and west sides ; conse- 

 quently, the returning action of the tree would have the ten- 

 dency to produce this large split in the centre of the trunk. This 

 action or stress is borne by a ship at sea in time of storm in a 

 similar manner, only in the case of a ship the stress is caused 

 by the waves underneath it, instead of the wind around the 

 tree. In what way does the stress rest upon a ship at sea 

 in stormy weather ? You are aware that the space between 

 crest and crest of the waves is generally about 60 feet, and 



