#82. NORFOLK. 347 



ajid, perhaps, what every year occurs in a 130, 

 greater or fmaller degree, a Michaelmas run 

 of the bark, with a Michaelmas Ihoot. 



This procefs of nature might be illuftratcd in, 

 the following manner. 



Suppofe four elailic vcffcls to be connected 

 in regular ferks, with narrow communications 

 between them j each channel of communication 

 being furnifhed with an claitic valve, requiring 

 a degree of force to open it ; but, being over- 

 come by fuperipr preflure, its clafticity weak- 

 ening, until entirely fpent. 



Suppofe this feries of elaftic veflels ftretched 

 flat upon a table (rcprefcnting the trcej, and 

 covered with a board (rcprefcnting its bark;. 

 This would refemblethe winter flate of the tree, 

 when the bark and the wood are in their nearefl 

 degree of contact. 



Suppofe further, a regular ftream of water 

 to be injected into the firft vellel. As the water 

 continued to flow, the veflel would fwell ; the 

 board be lifted by flow degrees from the table ; 

 and in this ftate reprefent, fufficiently, the 

 fpring run of the bark. 



The veflel being filled to the flretch, the firft 

 valve would begin to yield ; the buds of the 

 tree would burft, the leaves expand, and the 

 firing Jhoot be protruded. 



But 



