232 Chronicles of Science. [April, 



should exert the largest influence on the sun (assuming planetary 

 attractions to be the true disturbing agent) are Jupiter, Yenus, 

 Saturn, and the Earth. Estimated according to their attractive 

 effects merely, these planets should exert influences represented by 

 the numbers 70, 9, 7, and 5 respectively. But as the influence 

 exerted by Yenus depends on the distance of the planet from the 

 sun's equator, a large orbital inclination to this plane appears to be 

 an important element of disturbing influence ; so that the other 

 three planets whose inclination to the sun's equator is about twice 

 as great as that of Yenus, should exhibit a disturbing power pro- 

 portionately strengthened. Mercury, on the other hand, whose 

 influence Mr. Dunkin considers should be nearly as great as that of 

 Yenus, travels nearly in the plane of the sun's equator; and 

 further, the smallness of Mercury's mass is far from being " compen- 

 sated by diminished distance." 



The observers promise to give early attention to the influence 

 of Jupiter, which should exhibit a period of six years, since the 

 planet's sidereal period is about twelve years. In a later paper 

 they exhibit the close agreement between the observations made 

 at Kew, and those effected by M. Schwabe, at Dessau, during the 

 year 1866. 



The Astronomer Royal calls the attention of observers to the 

 opportunity which will be afforded them in the present year of 

 observing Jupiter without satellites. The phenomenon is very rare, 

 having only been observed twice, one of the observations being that 

 of Mr. W. E. Dawes. On August 21, Jupiter will be without 

 satellites for one hour and three-quarters ; and if the weather be 

 favourable, all the four disappearances and the four reappearances 

 may be observed in this country. They occur in the following 

 order : — at 8h. 14m., G.M.T. (soon after sunset), the third satel- 

 lite will enter on Jupiter's face; at 9h. 9m. the second satellite 

 will be eclipsed in Jupiter's shadow; at 9h. 28m. the fourth; 

 and at lOh. 4m. the first satellite will enter on Jupiter's face. All 

 the four satellites will then be invisible. At llh. 49m. the third 

 satellite will pass from Jupiter's face; at 12h. 13m. the second 

 satellite will reappear from behind the body of Jupiter; at 12h. 

 23m. the first, and at 13h. 54m. the fourth satellite will pass off the 

 disk. 



In a letter to Mr. Stone, Major Tennant, E. A., calls the attention 

 of astronomers to the total eclipse of August 17, 1868. This will 

 be visible in India ; and the certainty (almost) that east of the 

 Ghauts the weather will be fine, renders it the more desirable that 

 such of our observers as may be in India at the time should take 

 part in an observation of so much interest. " Probably," says Major 

 Tennant, " the Council will not think that it would be too much to 

 ask that the Government should, by organizing an observing party 



