Dr. Phillips on the Physical Aspect of the Moon. 557 



He lias lately preferred to use for his eye-draughts a fine achromatic 

 by Cooke, of York, — the same instrument which has been turned with 

 such unexpected results to a scrutiny of the solar spots. 



Professor Smyth of Edinburgh, and Professor Challis of Cambridge, 

 made examinations and preliminary sketches of the Mare Crisium, 

 Plato, and other interesting objects ; the former artist employing oil- 

 colours in his scene-painting. 



(b) By Photography. 



9. Meantime a new and beautiful art was making itself auxiliary to 

 the delineation of the moon, — first by the silver plate of Daguerre, 

 afterwards by the increasingly sensitive collodion surface. The great 

 achromatic of Cambridge, U.S., under the hands of Bond and 

 Whiffle, gave results of much promise ; at first the light-pictures 

 were of the full moon, 2 inches diameter on daguerreotype plates * ; 

 afterwards we saw larger representations of the crescent moon, with 

 stronger lights and shadows on the ridges and in the hollows, several 

 inches across (1851-53). 



10. While observing with the great reflector at Birr, every one was 

 struck with the probability that almost instantaneous pictures could be 

 obtained of the moon, stars, and planets, by the amazing quantity of 

 light brought to the focus of that magnificent instrument. Some 

 trials had indeed been made in 1852 by the distinguished constructor 

 and Mr. Woods ; but I am not aware of the results of later experiments 

 with the great reflector. In 1853 I gave much attention to the use of 

 collodion, and employed an apparatus attached to my achromatic 

 (of 1 1 feet focus and 6 inches diameter), by which at first pictures 

 of 1*2 inch diameter, and finally others from 2 to 3 inches were ob- 

 tained, in times gradually reduced from 5' to 30" and less. I still 

 possess many of these pictures ; the best, however, was destroyed in 

 attempting to print from it. 



11. Somewhat earlier than these trials of mine were the first 

 efforts of Mr. De la Rue, of which I was not aware. These efforts 

 have from year to year been rewarded with still increasing success, 

 till we have had from his skilful hands maps of the full moon of posi- 

 tive value, and stereographic pictures of admirable beauty. These 

 researches are still in progress, with every prospect of reaching a point 

 from which eye-draughts may be started on a fresh basis for a systema- 

 tic scrutiny of all parts of the moon, and the construction of maps on 

 the scale of -g'yth of an inch to a mile on the middle part of the moon's 

 face (or as the moon would appear under a power of 1000). 



12. Experiments rewarded by considerable success were completed 

 by the Liverpool Photographic Society in 1854 ; and several of their 

 valuable drawings of the moon, magnified to a large scale, were exhi- 

 bited at the Meeting of the British Association in Liverpool, along 

 with one of mine similarly handled. 



II. Proposal of a Method for further Progress. 



13. By the labours, for the most part uncombined, of the last ten 

 years, we have not achieved much beyond laying the foundation for 



* Kosmos, iii. 2. 362. 



