president's address — SECTION A. 73 



believed to be the first taken in England, and were of such excel- 

 lence that they would bear examination with a compound micro- 

 scope with a Sin. objective. 



Professor Bond^ had not been content with his successful photo- 

 graphs of the moon. He wished to see what could be done with the 

 stars; and, on July 17th, 185o, Mr. Whipple, under his direction, 

 placed a daguerreotyj)e plate in the focus of the great refractor and 

 obtained the first known stellar photograph — a picture of Alpha 

 Lyrae. The time it took is not given, but it is stated' that no 

 image of the pole star could be obtained, no matter how long the 

 •exposure was continued, but an elongated image of the double star 

 Castor was obtained before the experiments were given up. At 

 first it seems strange that a picture of the moon could be taken with 

 comparative ease, while bright stars, which we know are capable of 

 recording themselves in less than one-tenth of the time reqiiired for 

 the moon, required a much longer exposure, and in some cases 

 would not do it at all ; but it is obvious that the reason of this is to 

 "be found in the imjjerfection of the clockwork, which, instead of 

 keeping the star image fixed on one spot on the jjlate, c tuses it to 

 wander about that point until the light was too diffused to produce 

 the desired effect. 



In 1858** Dr. Luther, of Konigsberg, showed Mr. De La Rue the 

 daguerreotype of the total eclipse of 1 851 , which had been taken by 

 Dr. Busch with the Konigsberg heliometer. Considering the state 

 of photography at that time the successful i-esult was remarkable, 

 Avhen due allowance is made for the uncertainty then existing as to 

 the brilliance of the prominences. Towards the end of 1852 Mr. 

 De La Rue" took some photographs with the then new collodion 

 process on glass. He used his 13in. metallic reflector without clock- 

 work, and naturally met with considerable difficulty, although the 

 time of exposure, ten to thirty seconds, was very short for those 

 days. The work required two persons, and was very tiring, owing 

 to the number of failures. Motion was at first given to the telescope 

 I)}' means of the tangent screw, and then better results were ob- 

 tained by putting the sensitive plate in a slide and moving it to 

 follow the moon's apparent motion. This was done by hand, and 

 the amount of motion was determined by looking at a crater through 

 the transparent collodion film, and keeping it bisected by cross 

 wires attached to the back of the plate. Rough as these con- 

 trivances seem when measured by modern apj^liances, Mr. De La 

 Rue succeeded in making some excellent photographs, but, owing 

 to the ditf'culties, he came to the conclusion to discontinue the work 

 until he should get clockwork to move the reflector. 



These photographs were exhibited at a meeting of the Royal 

 Astronomical Society in 1853 ; they were ly-oin. in diameter, and 

 "were considered very good indeed. 



It appears'" that at this time (1853) the possibility of using 

 photography to delineate the surface of the moon became a burn- 



