how does the bobble hat helped evan escape from the prison? and who was the person whom stephendropped at the main gate after the examination was over?and at last how evans managed to escape under the governor's nos?please expets explain?

The bobble hat helped Evans to hide his cropped hair. Since all his scissors and blades had been taken away by Jackson, the officer, he was left with only one last blade which he used to crop his hair, the blade which Jackson was unaware of. This made Evans look like McLierry, the parson who had to conduct his exam. Exposing his hair would have ruined the plan as Jackson had keen observation and would have sensed that Evans was planning another escape.

The person who Stephen had dropped at the Prison gate was Evans' friend who was disguised as McLierry. This person should not be confused with Evans as at this time, Evans was in the prison cell, bathed in pig's blood and disguised as McLierry.

To know how Evans escaped from under the nose of the General, we must go back to the time when the General received a call for the requirement of a Police Car and two personnel for some case. Now, we come at the end. When Evans got arrested in the Hotel, he was put into the same Police Car which had been called above and the two persons inside were actually Evans' friends including the one who had disguised McLierry. After leaving the Hotel, they drove off and freed Evans. Thus, Evans successfully escaped from under the nose of the General