(3) of section 23 of the Income tax Act and observed as follows: "The rules laid down in that decision were these: (1 ) While proceeding under sub section (3) of section 23 of the Income tax Act, the Income tax Officer is not bound to rely on such evidence produced by the assessee as he considers to be false; (2) if he proposes to make an estimate in disregard of the evidence, oral or documentary, led by the assessee, he should in fairness disclose to the assessee the material on which he is going to found that estimate; (3) he is not however debarred from relying on private sources of informa tion, which sources he may not disclose to the assessee at all; and (4) in case he proposes to use against the assessee the result of any private inquiries made by him, he must commu nicate to the assessee the substance of the information so proposed to be utilised to such an extent as to put the assessee in possession of full particulars of the case he is expected to meet and should further give him ample opportunity to meet it, if possible.