I recd. yesterday yours of the 5th. Having full confidence in the judgment of Mr. Hassler, I take for granted that the scite chosen by him for an Observatory is well adapted to it. In comparing it however with others, it is necessary to attend to the difference in the degree of fitness, and in the cost of ground and of conveniency to the public. Mr. Munroe Superintendant of the City will furnish to the Secretary of the Treasury, or in his absence to the Attorny General, his ideas with respect to both, and I request the favor of you to communicate with the one or the other as the case may be, on the subject, and to obtain from Mr. Hassler his opinion as to any other scite next in fitness to that already selected, which Mr. Munroe will also take into his estimate and observations. When the scite shall have been finally decided on, I shall avail myself of your readiness to include the erection of the Observatory among the objects committed to your superintendance. In the mean time be so obliging as to send me the estimated expence of the building. Accept my respects