January 27, 1898] 



NATURE 



295 



factory all round." Mr. Bacon appears to have taken a 

 successful series of photographs with the cinematograph. 



Other information received via New York indicates 

 that the spectroscopic work of Prof. Campbell was also 

 successful. 



With such perfect weather, and the numerous powerful 

 instruments utilised, the results of this eclipse expedition 

 will form a unique record. A short account of some of the 

 larger instruments should, therefore, be of interest. 



For photographing the corona the Astronomer Royal 

 was provided with a telescope having an object-glass of 

 eight inches diameter, presented to the Royal Observ- 

 atory some years ago by Sir Henry Thompson. This 

 instrument gave an image of the sun's disc three inches 

 in diameter on a large-sized photographic plate ; the 

 plates employed were such as would be most likely to 

 show the delicate detail of the cloud-like structure close 

 to the sun's limb. 



Besides the photographs of the corona, Mr. Christie's 



ways. By drawing out the spectrum into a band of twice 

 the length the accuracy of measurement will be greatly 

 increased. Further, remembering that the sky was 

 slightly hazy in 1893, when eight coronal rings were 

 photographed, and that the use of a still greater dis- 

 persion, by spreading out the continuous spectrum of 

 the corona, will increase the chances of registering the 

 fainter coronal rings, it is not too much to hope that 

 the photographs taken during the eclipse will add 

 much to our knowledge of the chemical nature of the 

 corona. 



A 9-inch prismatic camera, in charge of Dr. W. 

 J. S. Lockyer, although of larger aperture than the 

 6-inch prismatic camera, had only one prism of 45^^, 

 giving a slightly greater dispersion than the 6-inch 

 with one prism. 



Each of these prismatic cameras was used in con- 

 junction with a siderostat, and pointed to the reflecting 

 mirror in such a way that the arcs of the chromospheric 



Fig I. — Prisms of the 6-inch Prismatic Camera. 



Fig. 2. — 9-in. Prismatic Camera in position for the Eclipse. 



photographs of the sun and moon, before and after 

 totality, will, no doubt, be of much value to the theory of 

 the lunar motion. 



Another large telescope for photographing the corona 

 was Dr. Copeland's 40-foot coronagraph, fixed up on 

 trestles and directed to the sun, the required movement 

 during totality being secured by a correct motion of the 

 plate. The diameter of the sun's image given by this 

 telescope is 4 inches. 



For spectroscopic observations, the prismatic cameras 

 with Sir Norman Lockyei^'s party were the most powerful. 

 Never before during an eclipse have spectroscopes with 

 so large dispersion and aperture been used. The 6-inch 

 prismatic camera used by Mr. Fowler had two large 

 prisms of 45°, instead of the one prism with which the 

 results of 1893 were obtained, the dispersion being thus 

 nearly doubled (Fig. i). This added power will tell in many 



NO. 1474. VOL. 57] 



spectrum at the beginning and end of totality were at 

 right angles to the dispersion. The accompanying illus- 

 tration (Fig. 2) shows the 9-inch prismatic camera in this 

 position. 



Besides the prismatic cameras the eclipse camp at 

 Viziadurg was equipped with other instruments for 

 making a complete set of observations, and by the help 

 of the officers, petty officers, and men from H.M.S. 

 Melpomene, the whole of the instruments, including the 

 coronagraph, with coelostat, integrating spectroscope, and 

 other spectroscopes for visual work, have been used. 

 Having previously been trained for all kinds of observ- 

 ations, these efficient volunteers have also made disc 

 observations and drawings of the corona, and observed 

 the effects of the eclipse on temperature, wind, landscape, 

 and other natural phenomena. 



The great interest taken in the eclipse in India 



