MEMOIRS 



AMERICAN ACADEMY. ^'e'rvX 



, BOTANICAL 

 OAVOBN 



I. 



Astronomical, Magneticul, and Meteorological Observations, made at Panama, Neiv Grenada. 



Br W. H. EMORY, 



BREVET MAJOR CORPS TOPOGRAPHICAL ENGINEERS, CHIEF ASTRONOMER AND SURVEYOR OP THE MEXICAN BOUNDARY COMMISSION. 



{^Communicated by W. C. Bond, Director of Harvard Observatory, Aug. 8lh, 1849.) 



The subjoined extracts from a letter addressed to Mr. Bond by Major Emory suffi- 

 ciently describe the instruments used in making the following observations, as well as 

 the mode of conducting them. The letter is dated Panama, May 8th, 1849. 



" Being detained here in our progress to San Diego with some of the instruments in- 

 tended for the survey of the boundary between the United States and Mexico, I have 

 occupied myself and assistants with making a short series of observations for latitude, 

 longitude, magnetic dip, declination, and intensity ; and with a series of meteorological 

 observations with the barometer, maximum and minimum thermometers, Daniell's hy- 

 grometer and the wet-bulb thermometer, and with a few observations for solar radiation 

 with the black-bulb thermometer. 



" The observations for latitude were made with a zenith telescope, with a focal 

 length of forty-two inches. The results are not as good as those obtained by me on the 

 Northeastern Boundary with the same instrument, owing to a slight derangement in its 

 parts from long service. The results may no doubt be improved by a more accurate de- 

 termination of the declinations of the stars used. 



" The computations were made by myself and Professor James Nooney, one of my 

 assistants. 



VOL. V. NEW SERIES. 1 



