328 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK in. 



constellations in the images thus obtained ; but a clear eye, without 

 glasses, could see more in the sky than could be shown by photo- 

 graphy. We congratulate ourselves on the new method of study 

 possessed in a very complete manner by several observatories, among 

 which we will mention the observatory of Wilna; but we neither 

 anticipate, by its intervention, any enlargement in the sphere of 

 action of practical astronomy, nor an overthrow of the art of taking 

 observations, such as resulted from the invention of astronomical 

 telescopes." 



Plate XIII., which represents two identical portions of the moon, 

 will enable us to testify to the correctness of Midler's judgment : 

 one is a facsimile of the selenographical map drawn by the illustrious 

 astronomer; the other is the enlarged reproduction of a fine lunar 

 photograph taken by Mr. Warren de la Eue. In the latter the relief of 

 the surface is admirably realised by the contrast of the lights and 

 shadows ; but one cannot distinguish a host of topographical details 

 of great interest which the astronomer, aided by powerful instru- 

 ments, has accurately delineated, and which convert his beautiful map 

 of the moon into a valuable monument for future selenographical 

 researches. 



Although there is still something to be said for the accuracy of 

 the position taken up by Msedler, the importance of photography in 

 astronomical work is being more and more acknowledged as the 

 processes are developed, and for such observations as require 

 daily registration, such as photographs of the solar surface, it is 

 already invaluable. 



