June 29, 1883.] 



SCIENCE. 



595 



servations. After the completion of the land- 

 ing, the men-of-war steamed away to Tahiti, 

 leaving selected members of their companies 

 to assist in the work. The American party 

 was favored with the help of Messrs. Qual- 

 trough, Dixon, Fletcher, and Doyle, officers of 

 the Hartford, and of ten seamen. 



The two weeks preceding the eclipse were 

 occupied in mounting the instruments and in 

 other preparations. Pendulum observations 

 during this time were made bj' Messrs. Preston 

 and Brown, under instructions from the U. S. 

 coast and geodetic survey-. The weather was 

 in general pleasant ; though there was one 

 severe rain-storm, and nearly everj' day there 

 were flying clouds with slight showers, as is 

 not unusual in the region of the trade-winds. 

 The wind was usually strong, and blew stead- 

 ily from a direction varying from north to east, 

 but never south of east, though the island is 

 in the heart of the south-east trade region. 

 Eight inches of rain fell during the seventeen 

 days which the part}- spent on the island, more 

 than Jialf of this in one storm on May 4. 



The weather on the morning of Maj' 6 was 

 cloudy and threatening ; but after several 

 showei'S the skj^ cleared shortly before the 

 time of first contact, and remained clear the 

 remainder of the day, with rapidly moving 

 clouds. One of these partially concealed the 

 corona for about twent}^ seconds in the first 

 minute of totalitj^, and the sun was whollj- in 

 a cloud soon after the close of totality ; but the 

 observations were not interfered with, though 

 there was at all times haze in the atmosphere. 

 Your readers have already' been informed of the 

 nature of the observations planned. All these 

 were carried out successfully, with results which 

 will be given in full detail in the official report 

 of the expedition. A summary of these results 

 can, however, be given at the present time. 

 Professor Holden swept for intra-Mercurial 

 planets, but discovered none. Spectroscopic 

 observations were made by Dr. Hastings and 

 Messrs. Rockwell, Brown, and Upton, with 

 interesting results. Dr. Hastings had devised 

 a spectroscope hy which the spectra of two 

 opposite sides of the sun were brought into 

 juxtaposition, and could be examined simul- 

 taneouslj'. This instrument, which was at- 

 tached to a 6^-inch equatorial, was used 

 especiall}' to note the changes in the appear- 

 ance of the 1474 line on the preceding and 

 following limbs of the sun as the eclipse pro- 

 gressed. At the beginning of totalit}- the 

 1474 line extended to a height of about 12' 

 on the eastern limb of the sun, while on the 

 western limb it was faint, and not more than 



4' in height. As the echpse progressed, the 

 lines changed relatively, becoming sensibly 

 equal at mid-eclipse, and the conditions at the 

 close of totality being the reverse of those at 

 the beginning. This change was many times 

 greater than anj- change due to the moon's 

 motion, and is regarded bj^ Dr. Hastings as 

 conclusive proof that the outer corona is main- 

 I3' due to difli'action. The dark D lines were 

 seen in the corona, and the bright hydrogen 

 and magnesium lines bj^ several observers. 

 The relative height and brightness of the coro- 

 nal rings seen in an integrating spectroscope 

 were estimated. 



The duration of totality was five minutes 

 twenty-five seconds. The corona was bright, 

 and characterized bj' five well-defined stream- 

 ers, a careful sketch of which was made b}- Dr. 

 Dixon. The azimuths of the shadow-fringes 

 at the beginning and end of totality were 

 obtained, and tlieir distances from each other 

 estimated. The meteorological observations 

 made by Mr. Upton showed a slight but well- 

 defined rise in barometric pressure, a rise in 

 humidity, and a fall in temperature. The tem- 

 perature reached the values given at night, 

 while the radiation thermometers indicated that 

 the receipt of heat bj' the earth was almost 

 wholly checked. The direction and velocity 

 of the wind were unchanged during the time of 

 the eclipse. 



The photographs obtained bj' Messrs. Law- 

 rance and Woods, the English members of the 

 party, who were assisted by Mr. Qualtrough 

 of the Hartford, include a series of negatives 

 of the corona to its outer limits, and also of 

 the coronal spectrum. The latter contains a 

 few bright lines, but not as many as were ob- 

 tained bj' the same observers in Egypt a year 

 ago. The phenomenon of reversal of the 

 Frauenhofer lines was also successfully photo- 

 graphed . 



The French astronomers obtained manj- pho- 

 tographic negatives of the corona, and of the 

 sky in the vicinitj- of the sun, to aid in the 

 search for Vulcan. M. Palisa searched for 

 intra-Mercurial planets without success. M. 

 Janssen saw dark*lines in the coronal spectrum, 

 and M. Tacchini a faint spectrum resembling 

 that of comets in one of the coronal streamers. 

 M. Trouvelot made a sketch of the corona, 

 and devoted also a portion of the time to the 

 search for intra-Mercurial planets. 



The Hartford returned to Caroline Island 

 on the 8th of May, and on the 9th sailed for 

 Honolulu, which was reached on the 30th; a 

 stop of four days having been made at Hilo, 

 Hawaii, to allow a visit to the volcano of 



