762 



SCmNGE. 



[N. S. Vol. XI. No. S81. 



torial 114-inch focal length, two 6-inch Dall- 

 meyer lenses of 40-inch focus, one of them 

 provided with a color screen and a special 

 Voigtlander lens of special construction of 

 4-inches aperture and 8-inches focal length, 

 also provided with a color screen. The spec- 

 troscopic work, under the direction of Pro- 

 fessor Ames, will embrace observations of 

 the reversing layer and corona with a con- 

 cave grating of 10-foot i-adius and rulings 

 6x3.5 inches, 15,000 to the inch, and a plane 

 grating with rulings of the same dimensions 

 used in connection with a quartz objective 

 of 3.5 inches aperture and 60 inches focal 

 length. A prismatic camera with a very 

 transparent prism of 6 inches length and 

 5.5 inches on the face, and an object-glass 

 of 4 inches aperture and 6 inches focal 

 length, will also be used at this station by 

 some of the observatory force, as yet unas- 

 signed. Dr. Dorsey will make observations 

 on the polarization of the corona with an 

 apparatus designed by himself, while Pro- 

 fessor E. R. Wood, of the University of 

 Wisconsin, in co-operation with other ob- 

 servers along the eclipse line, with an in- 

 strument designed by himself, will measure 

 the velocity, distance apart and direction 

 of the shadow bands. 



The second station on the central line 

 will be at Barnesville, Ga., under the im- 

 mediate supervision of Professor M. Upde- 

 graff, assisted by five of the regular staff 

 of the observatory. The operations at this 

 station will be similar to those at the last 

 in regai-d to latitude and longitude, and the 

 observations of the corona visually and 

 with the telescope. The photographic work 

 will embrace photographs of the corona 

 with the 40-foot photoheliograph lens, a 

 6-inch visual lens of 96 inches focus pro- 

 vided with a color screen, and a 6-inch 

 Brashear photographic telescope of SO 

 inches focus under the charge of Mr. C. A. 

 Post of New York, to whom the instrument 

 belongs. Additional photographs on smaller 



scale will betaken with a 6-inch Dallmeyer, 

 33 inches focus, a 4-inch Dallmeyer, 17 

 inches focus, and a 3.5-inch Dallmeyer, 9.5 

 inches focus, provided with a color screen. 

 The only spectroscopic work at this station 

 will be photographs of the reversing layer 

 and the corona with a slitless spectroscope, 

 under the charge of Professor H. C. Lord 

 of Columbus, Ohio, by whom it was de- 

 signed and constructed. 



The station at the northern limit near 

 GrilEn, Ga., will be for the study of the 

 reversing layer and the corona, and will 

 embrace observations with powerful grat- 

 ings both flat and concave. Professor Crew 

 and Dr. Tatnall of the Northwestern Uni- 

 versity will observe with a concave grating 

 of 10-feet radius ; Professor Humphreys of 

 the University of Virginia, assisted by Mr. 

 Dinwiddle of the same institution, will ob- 

 serve with a concave grating of 21.5 feet 

 radius ; while the grating objective will be 

 used by Mr. L. E. Jewell of the Johns 

 Hopkins University and Dr. Mitchell of 

 Columbia University, New York. This 

 instrument is identical to the one in use at 

 Pinehurst. The two flat gratings and the 

 concave grating at Pinehurst have peculiar 

 and unusual qualities for the special line 

 of investigation for which they will be used. 

 The size of the ruled space on these grat- 

 ings, and the peculiarities of the ruling) 

 which throws all the light into the first 

 order spectrum, gives a brilliancy to the 

 spectrum which could not be attained by 

 any practicable combination of prisms. 



It happens that a large number of parties 

 will congregate at Wadesboro, N. C, a 

 situation which the weather observations 

 for the past three years rather surprisingly 

 singled out as likely to be favorable in its 

 meteorological conditions. It is neverthe- 

 less unfortunate that these parties are not 

 more widely scattered along the path of 

 totality, so that fickle weather conditions 

 should not affect all alike. 



