for the year 1879. xvii 



undefined and somewhat nebulous spot, and conveyed to 

 me the idea of something in process of formation or change. 

 At the last meeting of the Royal Astronomical Society, 

 Mr. Neison, one of our best selenographers, described and 

 gave drawings of what he saw in March and April ; and 

 another well-known observer, Mr. Green, also furnished 

 drawings, which agreed with Mr. Neison's. The well-known 

 Melbourne photograph, taken with our great reflector, was 

 again used as a referee, so we must suppose it is still the 

 best photograph of the moon extant. The position of this 

 new spot with regard to Hyginus will be shown in the 

 course of the evening ; and Mr. Neison says about it — speak- 

 ing of the drawings made by Mr. Green and himself — " The 

 two drawings agree perfectly. There is no doubt, therefore, 

 that there now exists in this region a large conspicuous 

 object where no such object existed before; for it is so large 

 that it could not have existed and have been overlooked 

 by previous observers when they drew the much less 

 conspicuous objects on all sides of it." 



I told you last year of Professor Draper's discovery of the 

 existence of oxygen in the sun. He has continued his 

 researches, and has, I think, established the fact beyond all 

 doubt by most exhaustive experiments and observations. 

 Another element must now, therefore, be added to the list 

 already revealed to us by the spectroscope. This gas has 

 not yet been found to exist in our luminary in the two 

 stages of temperature in which hydrogen can be observed, 

 showing bright lines in the chromosphere, and dark in the 

 photosphere, for Professor Draper has found it only in the 

 bright line stage, indicating a temperature of far higher 

 intensity than that in which the vapours of the most of the 

 other substances in the sun appear to exist. 



The sun has been passing through the period of minimum 

 sun spots, a period which appears to recur every 10 or 11 

 years. Out of 169 photographs obtained with the helio- 

 graph, at our Observatory, 20 show the presence of sun 

 spots, but represent only 7 occasions on which a different 



