northern hemisphere, the attainment of which would be highly interesting and important.
4thly. That a correct knowledge of the courses of these lines, especially where they approach their respective poles, is to be regarded as a first and, indeed, indispensable preliminary step to the construction of a rigorous and complete theory of terrestrial magnetism.
"5thly. That during the progress of such an expedition, opportunities would of necessity occur (and should be expressly sought) to observe the transitory fluctuations of the magnetic elements in simultaneous conjunction with observations at the fixed stations and in Europe, and so to furnish data for the investigation of these changes in localities very unlikely to be revisited for any purposes, except those connected with scientific inquiries.
"Your Committee, in making this Report, think it unnecessary to go into any minute details relative to the instruments or other matériel required for the proposed operations, still less into those of the conduct of the operations themselves. Should such be required from them, it will then be time to enter further into these and other points, when the Committee will most readily devote themselves to the fullest consideration of the subject.
"J. F. W. Herschel,
"Chairman of the Joint Physical and
"Meteorological Committee."
