DOM 



Ex. Let the bell be a paraboloid, whose equation is #s 4 c *. 

 Here M = 2 c JT Is & m 2 c ' x x *- 

 /. x s -f (14 a -f A) x 8 = 14 * 

 from which equation x may be found. 



DOMINICAL Letter to find. 



RULE. Divide the centuries by 4, and take twice what remains from 

 , then add the remainder to the odd years above the even centuries, and 

 their fourth. Divide their sum by 7, and the remainder .taken from 7 

 will leave the number answering to the letter required. 



Thus to find the letter for 1820. 



The centuries 18 divided by 4 leave 2, the double of which taken from 

 6 leaves 2, to which add the odd years 26 and their fourth part 6, their 

 sum 34 divided by 7 leaves 6, which taken from 7 leaves 1, answering to 

 A the first letter of the alphabet. 



If it be leap year, the above rule gives the Dominical letter from the 

 end of February to the end of the year ; the letter immediately succeed- 

 ing will be the Dominical letter for the beginning of the year, from Janu- 

 ary to the end of February. 



Knowing the Dominical letter, we may, by the help of the following 

 Table, find the day of the week answering to any given day of the month, 

 and conversely. 



TABLE, 



