XX. An account of the magnetical experiments made on the western coast of Africa,1830-1, by Commander Edward Belcher, of H. M. S. Ætna. Communicated by the Rev. George Fisher, through Captain Beaufort, R.N. F. R. S

I have the honour of communicating the results of some experiments made on the western coast of Africa, by Commander Edward Belcher, of His Majesty’s ship Ætna, for the purpose of determining the relative horizontal intensities of the magnetic force, on the different parts of the coasts he has been lately surveying. The experiments were made with four needles, constructed for the purpose, on nearly the same plan as that adopted by Professor Hansteen, and made by Mr. Dollond. They were nearly cylindrical, and furnished with a move-able collar or suspension stirrup, for the purpose of adjusting them horizontally, and were respectively four, three and a half, three, and two and a half inches in length.