244 CARNEGIE INSTITUTION OF WASHINGTON. 



The photographs of Jupiter show numerous differences in light of the 

 different colors. On the infra-red images there is less darkening of the 

 disk toward the planet's limb and the cloud belts are very inconspicu- 

 ous. Moreover, the upper dark polar cap shades off gradually, while 

 on the violet and ultra-violet photographs the boundary is sharply 

 defined. The latter also show a doubling of the bright belt above the 

 equatorial zone which is not seen on the other negatives. 



The photographs of Saturn are of special interest. The infra-red 

 image shows the ball of the planet nearly devoid of markings, with only 

 traces of the belts visible. These are distinct on the yellow image, 

 which presents the usual visual appearance of the planet. On the violet 

 photograph, however, a very broad dark belt surrounds the planet's 

 equator, covering the region which is brightest in yellow light, and in 

 addition a dark polar cap of considerable size makes its appearance. 

 These dark regions appear also on the ultra-violet image with slight 

 modifications. They may be due either to the presence of a ring of 

 dust forming an extension of the crape ring down to the ball of the 

 planet or to the existence in the planet's atmosphere of some material 

 or gas capable of absorbing violet and ultra-violet light. The latter is 

 perhaps the more probable. 



Photometric measures of the density of the plates between the ball 

 and the ring, made by Mr. Babcock, indicate a greater density for the 

 ultra-violet than for the yellow image. 



DIRECT PHOTOGRAPHY. 



The following photographs of spiral nebulae were made during the 

 year by Mr. Ritchey at the Newtonian focus of the 60-inch reflector: 



X. G. C. 224 Exposure 9^ 10^ N. G. C. 4736 Exposvire 2'' O" 



2403 8 5857\ „ - 



2683 5 5859/ 



3627 1 0946 10 



Mr. Pease has obtained the following negatives at the same focus 

 of the reflector: 



N. G. C. 2371-2 Gaseous nelmla. 



2392 Planetary nebula. 



4594 Spiral nebula almost edge-on. 



5544—5 Two overlapping nebulce, one edge-on, the other in plan. 



6070 Spiral nebula in plan. 



6309 Gaseous nebula. 



6555 Spiral in plan in Milky Way. 



6703 rjaseou.s nebular .spot. 



A plate of Nova Lacerta', on which the North Polar Sequence was 

 superimposed, gave for the Nova a photogi*apliic magnitude of about 

 13.5. 



