It is demonstrated that high-$Q$ ($Q～{10}^8$) bottle microresonators can be fabricated by using a ${\mathrm{CO}}_2$ laser to heat a vertical single-mode fiber with a small weight attached to its lower end. A tunable continuous-wave laser is used to excite whispering-gallery modes in a bottle microresonator through a fiber taper, and a ringing phenomenon is observed. The observed ringing phenomenon is well explained through the numerical solution of a dynamic equation. In addition, an explicit function is given to describe the light field in the resonator, and the theoretical transmission based on the function also agrees very well with the experimental ringing phenomenon.