262 LAMPLAND— THE LOWELL OBSERVATORY 



prominence — cloudy and flocculent — with indications of 

 confused and overlapping arches. 



351°. 5 Prominence near the north pole. 



225° Pronounced rifts in the corona occur near these points, 



and the latter inclined, near limb, 20° or more southward with 



270° the radius. 



35° Four narrow and well-defined dark rays in brilliant coronal 



to matter, inclined a few degrees, northward, with the radius 



40° where rays start from the limb, but with gentle bending 



southward towards the equator with increasing distance 



from the limb. A number of broader and more diffuse 



dark lanes and streaks occur in different parts of the corona. 



Any detailed description of the appearance, distribution and 

 directions of the coronal rays for different regions will not be given 

 here. The variability and irregularity of their inclinations with 

 respect to the limb of the sun suggests the maximum type of corona, 

 though in some other respects characteristic features of the inter- 

 mediate type are present, as for example the general shape of the 

 corona as a whole is roughly triangular. 



In the Lowell Observatory photographs all of the prominences 

 except the one near the north pole are surrounded by arches or 

 envelopes or of disturbed coronal matter. Above some of the 

 prominences there are series of hoods or arches the forms of the 

 inner or lower ones being generally some oval curve, while the outer 

 or higher ones have forms resembling the pointed or ogival arch. 



One striking feature of these photographs is the disturbance of 

 the coronal streamers at and in the vicinity of the sun's poles. In 

 that respect the corona of 1918 resembles earlier ones observed near 

 sun-spot maxima, though as previously remarked it exhibits other 

 features characteristic of intermediate types. In the present photo- 

 graphs it would be difficult to estimate the position of the poles of 

 the sun from the appearance of the streamers. 



That there is an intimate relation between the prominences and 

 the surrounding coronal structure has at different times been ex- 



