There was a time when "abjuration of the realm" was considered a complete expiation for crime however heinous; but as the outer world became more civilised, and foreign parts more accessible, voluntary expatriation ceased to be the recognised alternative to punishment. The first result of the introduction of railways in this country (as far as the relation of crime to police is concerned) was to benefit the fraternity of thieves whose trade is essentially one that thrives best under nomadic conditions; subsequently, with the development of modern conveniences for travel, the police were again placed at a disadvantage, this time by the facility with which criminals, who are generally able to obtain at least a few hours' start, could find a safe refuge from their pursuers in some haven oversea--the modern equivalent for the mediæval sanctuary. There has ever been, and always will be, a ding-dong contest between the lawbreaker and the policeman, wherein the fortunes of the day favour first one side and then the other; for if the advantage that attaches to the opening gambit belongs to the criminal, his adversary is soon ready with an answer. The telegraph[248] beats the steamship, and the international system of police which now mutually provides for the surrender of fugitive offenders has restored the balance. The first extradition treaty in which Great Britain was interested was concluded with the United States of America in 1842, and the Extradition Acts of 1870 and 1873 now regulate the conduct of the English Government in its dealings with foreign powers in all that concerns this important department of police.[249] In 1879, a reform long agitated for was inaugurated by the tardy appointment of a Public Prosecutor, who became responsible that the cause of justice is not injured through the non-prosecution of persons guilty of serious offences. The intervention of the Director of Public Prosecutions is seldom deemed necessary, but circumstances occasionally arise in which lack of funds, local sympathy with the criminal, or an attempt to compound a felony, may demand his active interference.[250] The "Prosecution of Offences Act"[251] directs that Chief Officers of Police shall notify to the Director, that is to say to the Solicitor for the Treasury, such particulars of certain specified crimes committed within their districts as are described in the regulations[252] issued for the guidance of all concerned. CHAPTER XVIII DETECTIVE POLICE AND THE RIGHT OF PUBLIC MEETING