356 ANNUAL OF SCIENTIFIC DISCOVERY. 



Carolina, the difficulties seemed to accumulate ; the wide bays, sepa- 

 rated from the ocean by a narrow strip of land, disappear ; but, never- 

 theless, a scheme of triangles has been found perfectly practicable, and 

 a part of them have actually been traced upon the surface of the ground 

 itself. The triangulation and topography of Charleston Harbor are 

 finished, and the astronomical determinations made. 



" We have not materials for computing the date when this section 

 will be finished, but we can give a very fair estimate of it from what 

 we know by the reconnoissance, and limit the time for the land opera- 

 tions to two or three years. I have not supposed that we could under- 

 take more than six sections out of the eight unfinished on the Atlantic 

 and Gulf of Mexico. When any one was entirely finished, I could 

 take up a new section. Last year, by the wise liberality of Congress, 

 an additional appropriation was given for the Florida coast, which has 

 enabled me to begin another section. This is that important part of the 

 coast embracing what is called the Florida Reef and Keys, consisting 

 of the dangerous reef and of the chain of islands running westward 

 from Key Biscayne, and ending in the Tortugas. The reconnoissance 

 of this chain of islands has been nearly completed. 



" In section seventh, the reconnoissance has been made from Mobile 

 Bay towards the east, to include Pensacola Bay, connecting the work 

 with the base line measured on Dauphin Island in Alabama. 



" Section eighth is an interesting one, including as it does the high- 

 way betw r een two most important points in the Southern country, 

 Mobile and New Orleans. It includes the coast of Alabama, Mississip- 

 pi, and part of Louisiana. Here the progress of the work has been 

 very considerable. It was commenced in 1845, by a reconnoissance, 

 and followed up, the next year, by triangulation, the measurement 

 of a base, and the astronomical observations connecting the stations. 

 Now we have completed the triangulation from Mobile as far as Lake 

 Borgne, east of New Orleans. Another year we shall finish the tri- 

 angulation to New Orleans. The topography has kept pace with 

 the triangulation s ; and the hydrography, also, has very nearly 

 kept pace with them. Here we have not been without our reward, 

 any more than in the other sections, in usefulness, as the authorities 

 of Mobile have testified. The bar of Mobile Bay is actually deepen- 

 ing, and vessels can now carry twenty-one feet of water over it into 

 the bay. As a result of this discovery, the British steamers now 

 come into Mobile Bay, and have even found more water than we had 

 marked, by coming in at a time when the wind had heaped up the 

 water in the' bay. 



" Section ninth, including Texas, has been generally examined from 

 one end to the other, and more particularly near Galveston. The pri- 

 mary triangulations have been commenced in the neighborhood of 

 Galveston, and the secondary triangulation is nearly or quite complet- 

 ed in Galveston and Anahuac Bays. The topography will be com- 

 menced in the autumn, and the hydrography will at once follow upon 

 that. The astronomical observations necessary have been made. 

 What progress the Oregon and California sections may show, we can 



