Summary assessment powers to protect revenue allow immediate tax assessment and deem the person in charge liable when taxpayer is unascertainable. The proper officer, with prior approval of a senior commissioner, may carry out a summary assessment and issue an order when evidence indicates a tax liability and delay would harm the interest of revenue; where the taxable person for goods is unascertainable, the person in charge of the goods is deemed the taxable person. The Additional/Joint Commissioner may, on application or on review, withdraw an erroneous summary order and require assessment to follow regular procedural provisions.