THE NATIONAL SURVEYS.

The Secretary of War sent to Congress today a long letter from General Humphreys, chief engineer, reviewing in a caustic manner the late report of the National Academy of Sciences, of which he was himself a member, upon the subject of the national surveys. He calls attention to the fact that, of the committee of the Academy appointed to consider the subject, only one member had ever had any experience in kind of the surveys it recommends, while there were a number of members of the army well qualified from long experience for dealing intelligently with the subject. He criticises the vagueness of the report of the Academy, and the fact that very general terms are used where Congress desired something definite, and intimates that the report shows a want of accurate knowledge of the subject under consideration. He explains that the chief purpose of the survey proposed is to determine whether the curvature of earth is regular along parallels of latitude; and that while this problem was undertaken abroad, it required only joining systems of triangles of the several nations by short lines to make the whole useful to the end. Here it would require much costly work. As to the cost of the plan, he presents computations made by General Comstock, for many years in charge of the lake surveys, and from the results obtained after performing three thousand miles of triangulation of the same accurate character now proposed for the whole country. These calculations were made over three years ago, and so not with reference to the late report of the Academy. These show that for what General Comstock terms a rough topographical survey, based on points determined by primary triangulation, the cost would be for the whole country, excluding Alaska, one hundred fifty-six million dollars, and for a thorough geodetic, topographical and cadastral survey, which is what the Academy now recommends, the cost would reach four hundred and twenty million dollars.