Sir: I am very much to blame for having so long de-layed an answer to the agreeable and interesting despatchthat you have been kind enough to forward me, by thehands of Mr. Augustus Peterman, so estimable by hischaracter as well as by the solidity of his geographicallabors. Dr. Cullen cannot doubt the high importancethat I would attach to the merit of his courageous anduseful investigations in the eastern part of the Isthmusof Panama; knowing my position and my antediluvianage, he will receive with indulgence, even so late, the ex-pression of my lively gratitude. After having labored invain, during half a century, to prove the possibility of anoceanic canal, and to point out the Gulf of San Migueland Cupica as the points most worthy of attention; afterhaving regretted, almost with bitterness, in the last edi-tion of my “Aspects of Nature,” that the employment ofthe means which the present state of our knowledge af-fords for obtaining precise measurements has been solong delayed, I ought, more than any one else, to be sat-isfied to see at last my hopes for so noble an enterpriserevived. By your publications, sir, and by that of Mr.Gisborne, will be originated the great work of changingan important part of the commerce of nations, and ofrendering more accessible the rich countries of EasternAsia and the Indian Archipelago. The undertaking is byno means above the intellectual and material power whichcivilized nations have attained to. The work should beone to last forever; it should not commence with a canalwith locks, like the magnificent Caledonian canal; it mustbe a really oceanic canal, without a lock, a free passagefrom sea to sea, across which the course of the naviga-tion will be modified, but not interrupted, by the differ-ence in height and non-coincidence of the tides.