October 29, 1914] 



NATURE 



2Xi 



and solar comparison spectra, for the accurate 

 determination of the wave-lengths. 



The expedition was fortunate in having an 



Fig. I. — Corona, 2-4 scc, llford Process Plate. 



unobscured view of the eclipse during- the whole 

 period of totality, there being much_ cloud in the 

 sky at the time, and the returning- crescent being 

 hidden immediately afterwards. In the town of 

 Minsk, three miles away, practically nothing 

 was seen of totality. Thus the whole 

 programme of obser\-ations was carried 

 through. 



To the eye, the corona appeared bright 

 and of a steely-blue whiteness, and during 

 totality the darkness was not very intense. 

 Regulus could be seen shining through the 

 corona, and Mercury and Venus were also 

 visible. The corona was of the intermediate 

 type, with four streamers, and resembling 

 somewhat the 1898 corona. A sheet was 

 spread for the observation of shadow bands, 

 but none were observed. The temperature 

 readings taken during- the eclipse show that 

 the shade temperature fell 5*5° F., but the 

 humidity was not affected. 



With the coronagraph seven photographs 

 were taken, with exposures varying- from 2 

 to 25 sees., on llford Process, Empress, and 

 Special Rapid plates. These show a large 

 prominence on the limb of the sun near the 

 point of second contact, about one-twentieth 

 of the sun's diameter in height. In the 

 neighbourhood of this prominence the corona 

 shows some interesting detail in the form of 

 coronal arches. There was also a smaller 

 prominence on the other limb of the sun. The 

 shape and structure of the present corona is in- 

 teresting as compared with the records of past 

 coronas, inasmuch as it is of a type which has not 

 been previously studied, viz., that belonging to 

 NO. 2348, VOL. 94] 



the sun when near minimum, but with an increas- 

 ing spot-activity. Fig. i shows the corona, near 

 the commencement of totality, photographed on a 

 Process plate with an exposure of 2 seconds, 

 and developed with pyro-soda. Fig. 2 shows 

 it near the end of totality, the exposure being 

 5 seconds on an Empress plate, developed 

 with methol-quinol. 



With each of the telescopes with the colour 

 filters four exf)Osures were made, of 25, 40, 

 40, and 25 sees, respectively, the refracting 

 edges of the prisms being vertical for the 

 first two and horizontal for the second two 

 exposures. For the purpose of changing 

 from one position to the other, the telescojies 

 had been mounted so that their axes could 

 move upon the surface of a right circular 

 cone the axis of which was in the direction 

 of the beam reflected from the coelostat. 

 The presence of coronium in the corona 

 should be indicated on the photographs by 

 a sharp ring superposed upon a fainter back- 

 ground due to the dispersed continuous light. 

 The photographs taken enable us to assert 

 that any results obtained without the use of 

 prisms would have been of no value and 

 liable to misinterpretation. Beyond that 

 their evidence is negative. No trace of 

 coronium light is apparent, and, in the 

 absence of other evidence, it must be con- 

 cluded that coronium as indicated by the green 

 line was almost entirely absent from the present 

 corona. 



The photographs taken with the spectrograph 



Fig. 2. — Coroo^ 112-117 sec, I'ford Empress PIa;e. 



are good, though not quite so successful as had 

 been hoped for. More cannot be said about these 

 until they have been carefuUv measured. 



'H. S. Jones. 

 C. R. Davidsox. 



