286 THE POPULAR SCIENCE MONTHLY. 



nerve-centres. "We should see that a piece of news, a disaster, an 

 impending trouble or difficulty, causes a man to lay awake at night, 

 and we should know that he lies awake because his brain circulation, 

 either through the .whole or in parts of his cerebral hemispheres, 

 is higher than admits of sleep. There is an extrication of force 

 going on in the shape of thought, there is a flow of blood going to 

 the excited part. We cannot see all this, however, but we can and 

 do see how emotion causes the face to flush and the pulse to quicken, 

 how those who lie awake suffer from heat of head and suffusion of 

 eyes, how emotion increases the lachrymal secretion, the lacteal, 

 and others. And when we say that emotion does these things, we 

 merely mean that something or other has stimulated the brain into 

 producing these phenomena, and that along with the stimulus the 

 feeling of grief or shame or anger coexists. 



If all this be true, it may perchance throw some light upon many 

 of the phenomena of disordered mind and brain : it may help us \o 

 understand why, with almost the same delusion, e. g., that the news- 

 papers are writing about him, one man will be exultant, another 

 angry, another depressed ; it may explain why the same man is at 

 one time maniacal, at another melancholic. Lack of force may 

 account for the wretched feeling of the hypochondriac and the 

 hysterical, for the mental pain which many feel when they are 

 below par : and a proneness to part with force, to convert it into 

 action, may be the condition of the centres of those who are excitable 

 and impulsive, a condition analogous to that brought about in certain 

 centres by such drugs as strychnia, by such diseases as epilepsy and 

 'convulsions, or evidenced by such an affection as stammering. Fort- 

 nightly Heview. 



-- 



A GIANT PLANET. 



By EICHAED A. PEOGTOE, F. E. A. 8. 



WE propose to give a brief sketch of what is known respecting the 

 noble planet Jupiter. He is the giant of the solar system, him- 

 self the primary of a scheme of orbs whose movements resemble in 

 regularity the motions of the planets round the sun. Much has been 

 discovered during the last few years nay, even during the last few 

 months to render such a sketch interesting. 



We must, in the first place, dispossess ourselves of the notion, not 

 uncommonly entertained, that Jupiter is one of a family of orbs, nearly 

 equal in dignity and importance, and comprising the Earth and Venus, 

 Mars and Mercury, among its members. This idea still prevails, be- 



