DAY 



CYCLOID, principal properties of. 



1. Circ. arc E G G C. 



2. Tangent at C is parallel to the 

 chord EG. 



3. Cyduidal ar<- E C - 2 chord 



4. Area of cycloid 3 times area of the generating circle. 



.1. Solid generated by the revolution of the cycloid about its base A U : 

 it-' circumscribing cylinder :: 5 : 8. 



(\ Centre of gravity of the whole cycloid = - of the axis from the 

 vertex. 



7. Had. curv. at E = 2 D E. 



8. Equations to the cycloid ; put a diameter E D ; jc and y the co- 

 ordinates E K, K C ; x = arc E C ; z> - arc E G j then 



d x a* x~ " dx. 



and ij #'-}- Va x x*. 

 For the oscillation of a body in a cycloid, see Pendulum, 



D 



DAMS. See Fluids. 



DATES. See Chronology. 



DAY of the week to find. See Dominical Letter* 



DAYS, length and increase of, c. 



TABLE, 



Shewing^ ti-ith sufficient accuracy for common purposes, thf length and 

 increase of the days in this country, at different seasons of the year, to- 

 get her with the beginning and end of twilight. 



