ECLIPSE OF THE SUN, NEAR OLMOS, PERU. 7 



Capt. Fitzroy, R. N., places Fort San Antonio at Valparaiso in 71° 41' 15", and 

 as there is no important difference of meridians between his station there and 

 Mouatt's observatory, if the result from the 235 corresponding moon culminations 

 and occultations observed at Santiago is to be depended upon,^ Capt. Fitzroy's 

 longitude of Valparaiso is 3' 40" too great. His longitude of other points on the 

 west coast of America, being derived from chronometric differences, if his chrono- 

 meters had accumulated an unknown error of 14^67^ before arriving at Valparaiso, 

 all his determinations of places north of that city will probably be affected to at 

 least an equal amount. 



Correcting the longitude of Olmos given on Arrowsmith's map for the probable 

 error of 3' 40", and applying the distance of our station east of the town — 42" to 

 the result, we have for a preliminary longitude 80° 0' 8" W, 



Bringing forward to the morning of the eclipse the errors of the chronometers by 

 the rates given me at leaving New York, the results are : — 



Longitude by Arnold N". 6220 . . . . 79° 17' 36".6 



" Barraud N°. yf ^ . . . . 79° 27' 20". 1 



Mean 79° 22' 28".4 



From Payta to the station, these instruments were carried, during the day, in 

 inside pockets of my vest, and were necessarily jolted by the motion of the mule. 

 At night they were placed in the travelling bag which constituted my pillow. 

 There is no doubt that their rates were changed ; for the mean daily rate of Arnold 

 N°. 6220 was — 7'.85 between the morning observations of the 5th and those on 

 the afternoon of the 8th, against a daily losing rate of 1".8 with which it left New 

 York, and that of Barraud N°. y| ^ was — 6'.57 daily against — 3^5 daily. 



Using the preliminary longitude, and assuming as correct the tabular places given 

 in the American Ephemeris for 1858, Mr. F. G. Hesse, Assistant U. S. Astrono- 

 mical Expedition, has computed the following longitude whilst these pages have 

 been in preparation : — 



West 79° 42' 53".4 



THE ECLIPSE. 



The telescope specially completed and most courteously lent for the occasion 

 by Mr. Henry Fitz, of New York, is an achromatic, having an object-glass of 4i 

 inches clear aperture with a focal length of 5 feet 4 inches. It is supported upon 



' to observations of moon culminations subsequently made at the Santiago observatory, and computed 

 by Dr. Moesta, give for its longitude i^ 42" 32'.3'r. Still less I 



° Capt. Fitzroy says of his chain of chronometric differences round the globe : " It ought to be clearly 

 stated, however, that the sum of all the parts which form the chain amounts to more than 24 hours, 

 therefore error must exist somewhere ; but what has principally caused the error, or where it may be said 

 to e.xist, I am unable to determine. The whole chain exceeds 24 hours by about thirty-three seconds of 

 time." — Narrative of the Surveying Voyages of His Majesty's Ships Adventure and Beagle, Appendix 

 to volume II. page 345. London, 1839. 



