Royal Society. 



Explanation of the Construction of Tables T. and If. 



To render the preceding tables easv to be understood by 

 persons not . ;d fo calculations, I will state the" pro- 



cess (if the operation* in the firswline of Table II. 



The height of the tree at 12 years of age is supposed to 

 be IS feet to the top of its leading shoot, aud £4 inches hv. 

 circumference at the ground consequently, at half the height, 

 the circumference is 12 inches,— - one-fourth' of this, being 

 three inches, is called the girt. The girt being squared and 

 multiplied into the height, gives one foot one inch and six 

 parts for its contents. At J 3. years old the tree will be ig\ 

 feet high, 26 inches in circumference at the grcund 3 and 

 13 inches at half the height ; .one-fourth of 13 gives 3| inches 

 for the girt. This squared and multiplied into the height, 

 gives one foot five inches and one part for the contents. 

 Deduct from this the contents of the tree at 12 years of age, 

 and there remains three inches and seven parts, which isjhe 

 increase in the 13th year. Then reduce the contents of the 

 tree when 12 years old, and the increase in the 13th year, 

 each into parts, dividing the former by the latter, and the 

 quotient will be 3*76; by this number divide 100, and the 

 quotient is 26-5, which is the rate per cent, of increase made 

 hi the thirteenth year; consequently whatever the tree might 

 be worth when 12 years old,' it will, at the end of the 13th 

 year, be improved in value after the rate of 26/. 105. per 

 cent., or in other words, that will be the interest it will- 

 have paid that year for the money the tree was worth the 

 preceding year. 



At every succeeding period, both in this Table and Table I., 

 the like process is gone through. 



[To be continued.] 



LIX. Proceedings of Learned Societies. 



ROYAL SOCIJiTV. XML* 



April 13. — Earl of Morton in the chair. A paper by the 

 Rev. Mr. M° Gregor, on native arseniate of copper, was 

 Tead. The existence of this substance in nature has long 

 been hejd problematical, and its discovery in amine between 



50 and 



