LETTER FROM DR. BACHE. 481 



navigation, of the use to be made of it in 

 placing our signals, of the use as a foundation 

 for light-houses, and of many other questions 

 practically important and of high scientific 

 interest. I would place- a vessel at your dis- 

 posal during the time you were on the reef, 

 say six weeks. 



The changes at or near Cape Florida, from 

 the Atlantic coast and its silicious sand, to 

 the Florida coast and its coral sand, must be 

 curious. You will be free to move from one 

 end of the reef to the other, which will be, say 

 one hundred and fifty miles. Motion to east- 

 ward would be slow in the windy season, 

 though favored by the Gulf Stream as the 

 winds are " trade." Whatever collections you 

 might make would be your own. I would 

 only ask for the survey such information and 

 such specimens as would be valuable to its 

 operations, especially to its hydrography, and 

 some report on these matters. As this will, 

 if your time and engagements permit, lead to 

 a business arrangement, I must, though reluc- 

 tantly, enter into that. I will put aside six 

 hundred dollars for the two months, leaving 

 you to pay your own expenses; or, if you 

 prefer it, will pay all expenses of travel, in- 

 cluding subsistence, to and from Key West, 



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