310 Anniversary Meeting. [Nov. 30, 



When we consider how much water falls on Europe and Asia 

 during a month or two of rainy season, and how many weeks or 

 months must pass before it gets to the sea, and where it has been in 

 the interval, and what has become of the air from which it fell, we 

 need not wonder that the distance of the earth's axis of equilibrium 

 of centrifugal force from the instantaneous axis of rotation should 

 often vary* by 5 or 10 metres in the course of a few weeks or 

 months. We can scarcely expect, indeed, that the variation found 

 by the International Geodetic Union during the year beginning 

 June, 1891, should recur periodically for even as much as one or two 

 or three times of the seeming period of 385 days. 



One of the most important scientific events of the past year has 

 been Barnard's discovery, on the 9th of September, of a new satellite 

 to Jupiter. On account of the extreme faintness of the object, it 

 has not been observed anywhere except at the Lick Observatory in 

 California. There, at an elevation of 4500 ft., wibh an atmosphere 

 of great purity, and with a superb refractor of 36" aperture, they 

 have advantages not obtainable elsewhere. The new satellite is 

 about 112,000 miles distant from Jupiter, and its periodic time is 

 about 11 h. 50 m. Mr. Barnard concludes a short statement of his 

 discovery with the following sentences : " It will thus be seen that 

 this new satellite makes two revolutions in one day, and that its 

 periodic time about the planet is less than two hours longer than the 

 axial rotation of Jupiter. Excepting the inner satellite of Mars, it is 

 the most rapidly revolving satellite known. When sufficient obser- 

 vations have been obtained, it will afford a new and independent 

 determination of the mass of Jupiter. Of course, from what I have 

 said in reference to the difficulty of seeing the new satellite, it will 

 be apparent that the most powerful telescopes of the world only will 

 show it" (dated Mount Hamilton, September 21, 1892). 



Sir Robert Ball, in calling my attention to it, remarks that " it is 

 by far the most striking addition to the solar system since the dis- 

 covery of the satellites to Mars in 1877." To all of us it is most 

 interesting that during this year, when we are all sympathising 

 with the University of Padua in its celebration of the third cen- 

 tenary of its acquisition of Galileo as a Professor, we have first 

 gained the knowledge of a fifth satellite in addition to the four 

 discovered by Galileo. 



The President then presented the Medals awarded by the Society 

 as follows : 



See ' Brit. Assoc. Reports,' 1876, Address to Section A, pp. 10,11. 



