- [Footnote: miles), from the coast of the Pacific on the east of Panama.
On the Pacific side the isthmus is almost equally indented by the deep Golfo de San Miguel, into which the Rio Tuyra falls, with its tributary river the Chuchunque (Chuchunaque). This last-named stream in the upper part of its course approaches within 16 English geographical miles of the Atlantic side of the isthmus to the west of Cape Tiburon. For more than twenty years I have had inquiries made from me on the subject of the problem of the Isthmus of Panama, by associations desirous of employing considerable pecuniary means: but the simple advice which I have given has never been followed. Every scientifically educated engineer knows that between the tropics, (even without corresponding observations), good barometric measurements (the horary variations being taken into account) afford results which are well assured to less than from 70 to 90 French or 75 to 96 English feet. It would besides be easy to establish for a few months on the two shores two fixed corresponding barometric stations, and to compare repeatedly the portable instruments employed in preliminary levelling, with each other and with those at the fixed stations. Let that part be particularly examined where, near the continent of South America, the separating mountain ridge sinks into hills. Seeing the importance of the subject to the great commerce of the world, the research ought not, as hitherto, to be restricted to a limited field. A great and comprehensive work, which shall include the whole eastern part of the Isthmus,—and which will be equally useful for every possible kind of operation or construction,—for canal, or for]*
