▁of ▁ ƒ ( t 0 ,   θ ) ▁is ▁called ▁a ▁generating ▁circle ▁of ▁the ▁circular ▁surface . ▁ ▁Circ ular ▁surfaces ▁are ▁an ▁analog ue ▁of ▁ruled ▁surfaces . ▁In ▁the ▁case ▁of ▁circular ▁surfaces ▁the ▁gener ators ▁are ▁circles ; ▁called ▁the ▁generating ▁circles . ▁In ▁the ▁case ▁of ▁ruled ▁surface ▁the ▁gener ators ▁are ▁straight ▁lines ; ▁called ▁r ul ings . ▁ ▁References ▁▁ ▁Category : Sur faces <0x0A> </s> ▁Win fr id ▁Old field ▁Bur rows ▁D D ▁( 9 ▁November ▁ 1 8 5 8 ▁– ▁ 1 3 ▁February ▁ 1 9 2 9 ) ▁was ▁the ▁Bishop ▁of ▁Tru ro ▁and ▁later ▁Ch ich ester ▁in ▁the ▁first ▁third ▁of ▁the ▁ 2 0 th ▁century . ▁ ▁Born ▁into ▁an ▁ecc les iast ical ▁family , ▁Bur rows ▁was ▁educated ▁at ▁E ton ▁and ▁Cor pus ▁Christ i ▁College , ▁Oxford ▁and ▁ord ained ▁in ▁ 1 8 8 8 . ▁App oint ed ▁a ▁T utor ▁at ▁Christ ▁Church , ▁Oxford ▁in ▁ 1 8 8 3 ▁he ▁was ▁later ▁Princi pal ▁of ▁the ▁Le eds ▁C ler gy ▁School ▁and ▁afterwards ▁Vic ar ▁of ▁Holy ▁Tr inity ▁in ▁the ▁same ▁city . ▁He ▁was ▁vic ar ▁of ▁St ▁August ine ' s ▁Church , ▁Ed gb ast on ▁from ▁ 1 9 0 3 ▁to ▁ 1 9 1 2 ▁and ▁was ▁named ▁Arch de acon ▁of ▁B irmingham ▁in ▁ 1 9 0 4 . ▁In ▁ 1 9