1909] on Recent Results of Astronomical Research. 567 



in fact, the attention of the whole astronomical world — Morehouse's 

 comet— the comet which appeared last autumn, and which, although 

 it has long ceased to be visible in these latitudes, is still being 

 followed with great interest by observers in the southern hemisphere. 

 I daresay I am speaking to some here who will remember the great 

 comet of 1858 ; others will remember the comets of 1862, 1874 or 

 1882. I feel rather at a disadvantage in speaking of comets to you ; 

 comets nowadays are not what they used to be, and compared with 

 these glorious wanderers, the little comet of which I have to speak 

 made a very poor show. It will, I fear, be necessary to make out a 

 very strong case if you are to be persuaded that this little object, 

 which was hardly more than glimpsed with the naked eye by 

 practised observers, and was generally considered very disappointing 

 as seen with the telescope, is worth the attention that has been 

 devoted to it. 



Before proceeding further let me introduce the comet under 

 consideration. Here it is as it appeared on September 30 last year. 

 [Two photographs were thrown in succession on the screen.] But 

 I think no one could undertake to recognise it again from its 

 photograph. Here is the same comet a day latei*^ Everything is 

 altered completely ; you cannot point to a feature in the tail on this 

 photograph and say that it corresponds to a certain feature on the 

 previous photograph, and that one has changed into the other ; you 

 cannot say that this is the tail of the previous day modified. As far 

 as can be judged the tail is an entirely new one, and if these two 

 photographs were all the data available we might, it is true, learn 

 something of the mode in which the activity breaks out and dies 

 away from day to day, but it would not be possible to trace the 

 motions of the particles of the tail, and the most hopeful line of 

 research by which something may be understood of the nature of the 

 comet's tail would be closed. Now that is what has generally 

 happened in the case of the former comets, at any rate, since it has 

 been possible to apply powerful telescopes and the best photographic 

 methods to the study. Most comets, and the same applies to planets 

 and satellites, are well placed for observation for, say, three hours at 

 a time, but, the rest of the night, are too close to the horizon to be 

 satisfactorily photographed. But this comet for a month or so 

 after its discovery chanced to be in the neighbourhood of the North 

 Pole, so that it simply circled in a small path round the Pole during 

 the twent*y-four hours, and the whole night long from dusk to dawn 

 it was in a favourable position for being photographed. That is the 

 first factor which rendered this comet an important one — its 

 exceptional position. An observatory in a high latitude like ours is 

 generally at a great disadvantage compared with one at the equator ; 

 we, for instance, never have an opportunity of seeing Mars under 

 really good conditions ; but for once high latitude was useful. 



It was very soon realised that here was an unusual opportunity 

 Vol. XIX. (No. 103) 2 v 



