106 



REPORT OF THE SECRETARY. 



The greatest extension obtained exceeds tliree diameters from the moon's limb. 

 Here the streamers fade away into tlie background of sky, as if overpowered by 

 skylight rather than as here ending. 



5. TJie combination of four wide-field cameras. — These cameras were all in a measure 

 successful, though not in equal measure, for one of the long-focus and one of the 

 short-focus negatives was better than its mate, the former being on a better plate 

 and in better focus, while the short-focus camera with screen showed unaccountable 

 effects of motion not found in any others. 



Comparing the long-focus with the shoil-focus negatives, the former were far supe- 

 rior both as corona pictures and as showing faint stars. One of the 11-foot focus 

 negatives has probal)ly the best general view of the corona secured by the expedi- 

 tion. (See Elate XVII. ) On this plate the corona is seen as a whole. It hardly shows 

 the full extent of the corona, which, as seen by the naked eye, extended to nearly 

 three solar diameters, but it exhibits most clearly the curves on either side of the 

 solar streamers, although perhaps not showing quite as great extension as that 

 obtained with the 6-inch photograiihic telescope. 



As regards faint stars and new objects, the better of the two 11-foot focus negatives 

 covering the region west of the sun shows 114 stars, the faintest being of the 8.4 

 magnitude as given in Argelander's Durchnnisterung, a result which, considering the 

 amount of diffused light during the eclipse and the milkiness of the sky, is almost 

 surprising. Six uncharted objects were found upon this plate, which ajjpeared star- 

 like and may conceivably Vje intra-mercurial planets, though nothing is to be under- 

 stood as here predicated of them until a later and careful examination of the plates. 



This photograph was unsuited for purposes of direct reproduction for the reason 

 that the fainter stars required the best of conditions for seeing even on the original 

 and would inevitably have been lost. It was nevertheless thought interesting to give 

 an accurate map showing all the stars and suspects f(jund, and this is done in Plate 

 XVIII. The general reader will perhaps gain a better idea of the value of photog- 

 raphy as an aid to investigation when he sees in this map, oTjtained in eighty-two 

 seconds exposure, in a brighter than moonlit sky, not only the corona and the planet 

 Mercury just beyond its rays, but more stars near the Pleiades than he can see with 

 the unaided eye in the darkest night. Astronomers are invited to compare this map 

 with the Durchmusterung charts, to see both the strong and the weak points o^ 

 the plate. It will be recognized that the outer portions of the map show fainter 

 stars than the middle part, and thus it is indicated that advantage in focus would 

 have come if the plate had been slightly concave. 



The negative covering the region east of the sun was much less satisfactory, and 

 showed but 13 stars, the faintest being of the 6.3 magnitude. Two uncharted objects 

 were found, but of their starlike character there is less certainty than in the case of 

 four of the six discovered on the western plate. 



The positions of these objects as interpolated on the Durchmusterung charts for 

 the epoch 1855 and their approximate position for 1900 are as follows: 



EPOCH 1855. 



