The object of section 172 in providing for the maintenance of a diary of his proceedings by the police officer making an investigation under Chapter XII has been admirably stated by Edge, C.J. in Queen Empress vs Mannu(1) in the following words: 156 "The early stages of the investigation which follows on the commission of a crime must necessarily in the vast majority of cases be left to the police, and until the honesty, the capacity, the discretion and the judgment of the police can be thoroughly trusted, it is necessary, for the protection of the public against criminals, for the vindication of the law and for the protection of those who are charged with having committed a criminal offence that the Magistrate or Judge before whom the case is for investigation or for trial should have the means of ascertaining what was the information, true, false, or misleading which was obtained from day to day by the police officer who was investigating the case and what such police officer acted.