Estimate of appropriation -- Internal Revenue Service. Letter from the Secretary of the Treasury, transmitting an estimate of appropriation in the sum of $4,583,000 required for the Internal Revenue Service for the remaining nine months of the fiscal year 1918, and a request for authority to use the estimated unexpended balance of the appropriation "salaries and expenses of agents and subordinate officers of internal revenue, 1918," for the employment of deputy collectors and inspectors as provided in the Act of September -- , 1917.