Sir—I am very much to blame for havingso long delayed an answer to the agreeable andinteresting despatch that you have been kindenough to forward me, by the hands of Mr.Augustus Peterman, so estimable by his cha-racter, as well as by the solidny of his geo-graphical labours. Dr. Cullen cannot doubtthe high importance that I would attach to themerit of his courageous and useful investiga-tions in the eastern part of the Isthmus ofPanama: knowing my position and the ante-diluvian age, he will receive with indulgence,even so late, the expression of my lively gra-titude. After having laboured in vain, duringhalf a century, to prove the possibility of anoceanic canal, and to point out the Gulf of SanMiguel and Cupica as the points most worthyof attention; after having regretted, almostwith bitterness, in the last edition of my“Aspects of Nature,” that the employment ofthe means which the present state of ourknowledge affords for obtaining precisemeasurements has been so long delayed: Iought, more than any one else, to be satisfiedto see, at last, my hopes for so noble an enter-prise revived. By your publications, sir, andby that of Mr. Gisborne, will be originated thegreat work of changing an important part of thecommerce of nations, and of rendering more ac-cessible the rich countries of Eastern Asia andthe Indian Archipelago. The undertaking isby no means above the intellectual and materialpower which civilised nations have attained to.The work should be one to last for ever; itshould not commence with a canal with locks,like the magnificent Caledonian Canal; itmust be a really oceanic canal, without locks;a free passage from sea to sea, across whichthe speed of the navigation will be modified,but not interrupted by the difference in heightand non-comeidence of the tides.—Receive, Ipray you, air, the expression of my highestcunsideration. Yours, &c., &c.