Sepiembee 16, 1898.] 



SCIENCE. 



343 



cially in the faithful delineation of the sur- 

 face features of the sun and the moon, for 

 these two objects, at least, were bright 

 enough to register themselves with the 

 sluggish materials then in use. It is spe- 

 cially gratifying to Americans that the first 

 efforts to utilize the new discovei-y for the 

 benefit of astronomy were made in this 

 countrj^, and that Americans have alwaj's 

 been prominently identified with the pro- 

 cess from its very earliest conception. 



Within less than one year from the 

 announcement of Daguerre's discovery, in 

 March of 1840, Dr. John W. Draper, of 

 l^ew York City, had succeeded in getting 

 pictures of the moon which, though not 

 very good, foreshadowed the possibilities of 

 lunar photography. Five years later the 

 Harvard College Observatory may be said 

 to have commenced its remarkable career 

 of astronomical photography, when Bond, 

 with the aid of Messrs. Whipple and Black, 

 of Boston, succeeded in getting still better 

 pictures of the moon with the 15- inch re- 

 fractor. ■ These pictures, on daguerreotype 

 plates, seem to have been fairly good, and 

 to have shown much detail, though the 

 telescope was wholly uncorrected for the 

 photographic rays. They attracted a very 

 great interest in the subject, especially in 

 England, but the difficulties encountered 

 led to failures generally, except in the case 

 of De La Rue, Dancer and one or two 

 others. To Dancer is doubtless due the 

 earliest success in lunar photography. Ex- 

 cellent photographs, it is said, were made 

 by him as early as February, 1850. In 

 1858 De La Rue, using a 13-inch metal 

 speculum, without clockwork, and guiding 

 by following a lunar crater seen through 

 the plate, made the most important of the 

 early efforts at lunar photography. From 

 this time De La Rue made the best pictures 

 of the moon until the subject was taken up 

 again in America in 1860 by Dr. Henry 

 Draper, son of the illustrious John W. 



Draper. Like De La Rue, Dr. Draper con-, 

 structed his own telescope, a 15J-inch re- 

 flector. With this instrument he secured 

 excellent photographs of the moon, superior 

 to any previously made, and capable of 

 considerable enlargement. These pictures 

 were the best taken until Lewis M. Ruther- 

 furd began his remarkable work about 1865. 

 Rutherfurd's work marked the most impor- 

 tant step until then made in astronomical 

 photography. From this time on he pro- 

 duced such admirable photographs of the 

 moon that they have not been excelled until 

 within the past few j'ears. These were 

 made with a refractor of 11-inches aperture 

 which had been constructed under his im- 

 mediate supervision. It was the first 

 telescope corrected specially for the photo- 

 graphic rays. Some excellent lunar photo- 

 graphs, in the meantime, had been made 

 with the great four-foot refiector of the 

 Melbourne Observatory. 



The completion of the Lick Observatory 

 in 1888 marked another decided advance 

 in the photography of the moon. The 

 great focal length of the magnificent in- 

 strument gave an unenlarged image of the 

 moon about six inches in diameter, which 

 in itself was a great advantage. 



The admirable lunar photographs made 

 by MM. Loewy and Puiseux, with the equa- 

 torial coude at Paris, in the past few years 

 have excelled anything yet made in this 

 direction. 



But what is shown by the best lunar 

 photographs has not yet approached that 

 which can be seen with a good telescope of 

 very moderate size. The minute details 

 are at present beyond the reach of photog- 

 raphy, but its accurate location of the less 

 difficult features is of the highest value. 

 The greatest interest in any observation of 

 the moon would be in any changes that might 

 take place on its surface. It has long ago 

 been shown that no changes on a large scale 

 have occurred in recent times. It is, there- 



