i8o THE POPULAR SCIENCE MONTHLY. 



that are consumed in a few hours. Oxygen is absorbed more rapidly 

 than it is set free. We shall also have to give up the prevalent idea 

 that a little verdure can improve the atmosphere of a room. The ad- 

 vantage of plants, as Dr. Pettenkofer remarks, is rather in their moral 

 than in their physical influence. Public gardens are also desirable be- 

 cause they enliven the view. Even on hygienic grounds, we should 

 be careful not to underestimate the importance of whatever acts upon 

 the mind. AVe have endeavored, in this and a former essay,* to study 

 clothing and the habitation, with particular reference to their relations 

 with the atmosphere ; but, even as thus limited, the subject has proved 

 to be a very complex one, and in our progress we have struck upon more 

 than one question that is still imperfectly elucidated. It may, however, 

 not have been without use to attract attention to these questions, which 

 demand new investigations. Hygienic societies are multiplying ; de- 

 partments of hygiene have been created in numerous cities ; and the 

 hygienic conferences which have been held at Paris, Turin, and Ge- 

 neva, attest the growing interest that attaches to the development of 

 a science all of whose conquests redound to our physical and moral 

 profit. Every facility should be given for widening its scope and ex- 

 tending its sphere of action. Diseases that might have been avoided 

 constitute the heaviest taxes that can be laid upon a city. Translated 

 for the Popular Science Monthly from the Revue cles Deux Mondes. 



< 



A BELT OF SUN-SPOTS. 



By GAEEETT P. SEEVISS. 



EVERYBODY who watched the sun with a telescope last summer 

 must have wondered at the great belt of spots lying across the 

 southern part of the disk during the last half of July. Several of the 

 spots and groups were of extraordinary size, and their arrangement 

 was very singular. When the belt extended completely across the 

 sun, there was visible at one time almost every characteristic form that 

 sun-spots present. There was the yawning black chasm with sharply 

 defined yet ragged edges, vast enough to swallow up the whole earth, 

 with room to spare, and surrounded by a regular penumbral border as 

 evenly shaded as an artist could have made it ; there was the double 

 or triple spot whose black centers, though widely separated from one 

 another, were tangled, as it were, in one twisted and torn veil of 

 penumbra, or connected by long, shadowy bands ; there was the mon- 

 strous spot of grotesque form surrounded by a crowd of smaller spots 

 of even more fantastic shape, and enveloped in a broad, irregular pe- 

 numbra as bizarre and wonderful as the mighty sun-chasms inclosed 



* " Popular Science Monthly " for October, 1883, p. 787. 



