for the year 1878. xvii 



The transit of Mercury across the sun's disc in May last 

 was a noteworthy event, and its later phases were success- 

 fully observed at the Observatory, but no new points of 

 interest in connection with this phenomenon were noted. 

 The opposition of Mars on the 6th September last year 

 occurred when that planet was unusually near to the earth, 

 and a remarkably good opportunity presented itself of again 

 determining the solar parallax. In conjunction with Euro- 

 pean and American observatories, we undei-took a series of 

 observations for parallax in declination, and succeeded in 

 securing a fine set of measures, extending from 21st July to 

 22nd October, the results of which will probably be known 

 by the end of the year. 



Encke's comet again returned to perihelion on July 26th. 

 Last mail I received a particular request from Professor 

 Asten, of Pulkowa, that we should endeavour as it came 

 south to obtain as late observations of it as possible. It is 

 now too near the sun to be seen, but we hope to pick it up 

 in a few days. This comet was first observed in 1786, and 

 since that year it has made 28 consecutive revolutions round 

 the sun with remarkable regularity ; in only 20 of these, 

 however, has it been observed. In 1822 it was seen only at 

 the Observatory of Paramatta. Great interest is attached 

 to the observation of this comet, owing to the fact that each 

 succeeding revolution is made in less time than the last, thus 

 showing that the comet is diminishing its mean distance 

 from the sun. This would appear to indicate that it 

 experiences resistance in its course, which, if continued, will 

 ultimately cause it to fall into the sun. At the present time 

 its revolution round the sun is accomplished in a period 

 which is more than two days less than at the time of its 

 discovery in 1786. 



Some important additions to the Literature of botanical 

 science have been made during the past year. Our fellow- 

 member, Baron von Mueller, the Government botanist, has 



a2 



