A correspondent of the N. Y. Tribune, writingfrom San Francisco, gives au oocount of the Caroline [sland observaáon of the solar eclipse, as gathered !rom members of the party. We make a few exlracts from his letter: The-party, numbering oight, including two observers sent out, by tbc rojal society of Englaad, left Callao, Peru, on the 8th of March, Caroline i.sland their destination, was reached on April 20, and proved to bc a chain of gmall coral islands encircliag a lagoon. These islands are not barren, but produce on excellent growlh of v'egetation. including a largo number of coconnut and other trees. A small deposit of guano is found, and together with cocoamits is made an article of export, by the lirm oí Houlder Brothers, of London. who lease this and other Pacific Islands f rom the ïnglish government. At the lime of the visil of the astronómica] expedltion, sevcn persons werc living on the island; four men, onc of whom was accompanied by hls wtfe and two children. These had been brought from Tahiti two months beforc by the agent of Houlder Brothers to take care of the young cocoamit trees and the property left on the island. The lattcr ïncfuded seyeral substantial frame housea and a quantity of tools, stores, etc. The houses fur nished acceptable accommodations to the visitors who thus found unexpeotod luxuries in their camp life. The American party was inercased to twelve by tho addition of four officers from the" Hartford, Messrs. Qualtrough, Dixon, Fletcher and l)oylo, who were assisted b)' teu members of the crew. The two weeks preceding the date of the eclipse wero spent in mo uiting thö inBtruments and in other preparations, in making observations for time and laütiide, and noting the meteorological eonditions of the island. Messrs. Preston and Brown also carried out the nst.ruc'iuns of the United States Coast Survey by making pendulum observations to determine tne forcé of grait at this island. The wcather dunngtbis fortnight was in general pleasant, but characterized bv l'ying cumlus cloudsi with occasional showers. There was i one rainy d'ay, thorainfall amounting in eight hours to uearly five inehes, while tlie total rainfall during tlu stay on the island was eight inehes. The wind was uniformly from the nnrth or cast, but never from a point south of east, thougli th island is in the región oí the southeast trades. On tho morning of the eclipso the weather was very unfavorable, but before the all-important event occurred, the clouds cleared away, and the entire period of totality was favorable for the observers. All four contacts were observed, and the vexed question of interniercurial planeta has at last been definitely settled, no such planets being discovered. Photographs were obtaincd by tlie Frenchmen of the sky in the vicinity of the eclipsed sun. The speetroscope observations give interesting results. especially those of Dr. Ilastings, who used a G0 prism attached to a C.l-inch equatorial. The special feature of the apparatus, however, was two total rellecting prisma placed in front of the Ut, by which the spectrum from two opposite sides of the limb could be brought into juxtaposition and examined simultaneoualy. This was used to observe the appearance of the 1,474 coronal line on the eastern and western limbs of the sun and to note tho changos as the eclipse progressed The extensión of the coronal Unes was found to vary greatly on the eastern and western limb. But as the eclipso advanced this inequauty vanished, and tho lines became equal in higlit and brightnoss. Dr. Hastíngs regards tli3 observation as conclusivo prooi that the outcr corona is mainly a nhenomenon of tion, since this change was many time greater than any due to Uie moon's motion alone. The chromosphere was unusually quieBcent and tlic prominences few. The corona was bright and was charaeterized by liire well deiined streamers, which were aketched by Dr. Dixon. The azimuthsj of the shadow fringes at the beginning and end of totality were obtained and their distances estimated. The meteorological observations made byMr. Uptonshowed a well marked rise in barometric pressure amounting to 0.02 inches, a rise in luunidity of 5 per cent. ; a fall in terupcrature to that of night, and absolute steadineso in both the direction and velocity of the wind. Tho radialion observations shovved that the receipt of heat by the earth i'rom nny som-ce was ahnost wliolly ehecke:!. The nibmbers of tho expodilion remalned on the island for several days after the eclipse, when they left for Hanolulu, where they arrived May 80. At this port several of tho observers remaineCI in order to proceed to the island of Maui and there make pendnlum obserratioos, as instrueted by the United States ('oast Snrvey. The other menibers of the expedition lelt on June ! in the steamer Zealandia, which reached San Francisco on the llth inst. The observers are pleascd witli the resulta of their observations, and will submit the full report of their work lo tlis Committee of the National Aeademy at au early day.