1867.] Astronomy. 89 



filling in from Professor Phillips' map, our astronomical readers 

 will be enabled to obtain views of the planet at successive 

 intervals of two (Martial) hours. Such views would suffice 

 for comparison with any telescopic views taken near the time 

 of southing,* or with views taken at any hour, if due regard be 

 paid to the varying slope of the planet's axis. Towards the end of 

 February the planet (now become much smaller) will appear per- 

 ceptibly gibbous ; his maximum stage of gibbosity, attained early 

 in April, and his apparent disc at that time are exhibited in 



Fi S- 2 : 



Owing, apparently, to a change of authorities, the apparent 



diameter assigned to the planet in the ' Nautical Almanac ' is larger 



for January 10, 1867, than for December 1st, 1864. Observers, 



however, must not expect to find the planet larger ; in fact, he will 



be more than 9,000,000 miles farther from the earth on January 



10th, than when in opposition in 1864. 



Two more minor planets, the 90th and 91st, have been disco- 

 vered : the first by Dr. Luther, of Bilk, near Diisseldorf, on October 

 1st ; the second at the Marseilles observatory. 



On the 6 th of March there will be an annular eclipse of the 

 sun, visible throughout England as a partial eclipse. It will begin 

 at Greenwich at 8h. 17m. a.m.,. and reach its greatest phase at 

 9h. 32m. a.m., and end at lOh. 52m. a.m. About seven-tenths of 

 the sun's diameter will be obscured at the time of the greatest 

 phase. 



We call the special attention of our readers to the obscuration 

 of the Lunar Crater Linne (on the Mare Serenitatis) observed by 

 Herr Schmidt at Athens. The epoch at which the crater again 

 becomes visible should be carefully noted. This is the same crater 

 that Schroter saw transformed into a dark spot on November 5th, 

 1788. 



Proceedings of the Koyal Astronomical Society. 



Professor Kaiser, of Leyden, in a letter to the Astronomer- 

 Eoyal, discusses the qualities of the latter 's double image micro- 

 meter. He expresses a favourable opinion on the instrument, but 

 in one respect astronomers will be disappointed. It has long been 

 known that measurements effected by the best observers with the 

 wire -micrometer present considerable discrepancies. Now, if it had 

 resulted from Professor Kaiser's experiments that the instrument 

 was in fault in such cases, there would have been a prospect of 

 remedying the evil. It appears, however, that the same observer 



* The horizontal line through the centre represents the true path of the 

 planet ; at the moment of " southing " the slope of the axis will be a few degrees 

 less than iu Fig. J, since the planet's motion in opposition will be carrying him 

 slightly northwards. 



