ADVISORY COMMITTEE ON ASTRONOMY 11 5 



the discovery and accurate obser\''ation of comets has been prose- 

 cuted for a long time with much judgment, abiHty, and success. 



Some years ago substantial prizes v/ere offered for the discovery 

 of comets. In those days several enthusiastic amateurs were enlisted 

 in this work, with the result that the sky was constantly patrolled, 

 and astronomers had a reasonable assurance that no comet of any 

 consequence was likely to escape discovery. This is a matter of 

 importance, because it would be interesting to learn whether, as has 

 been suspected, more comets are seen at the times of greatest solar 

 activity, with the consequent inference that the envelopes of these 

 comets are excited by the magnetic condition of the Sun. 



Meteors. 



The interest in the observation of meteors suffers no diminution. 

 Of late years a systematic effort has beeti made to photograph some 

 of these objects in flight. These efforts have been attended with 

 partial success. By means of photography, 'an incalculable advance 

 in the exact astronomy of these bodies becomes possible, and this 

 method is deserving of encouragement. This work has been carried 

 on for several years at the Winchester Observatory of Yale Uni- 

 versity, 



Double Stars. 



Thirty years ago interest in the observation of double stars ap- 

 peared to be on the wane. The unsatisfactory nature of the orbital 

 computations which were made from time to time on the basis of 

 exceedingly minute quantities of slowly changing relations led to 

 something like a feeling of despair. Comparatively few binary 

 stars have a period of revolution less than one hundred years. Of 

 the vast majority the period of revolution is at present entirely con- 

 jectural. Revival of interest in this branch of astronomy was largely 

 due to an American amateur astronomer, Mr. S. W. Eurnham, who 

 began his labors with a small telescope. Graduating from this into 

 regular astronomical employment, with the use of large telescopes 

 Mr. Burnham added a large number of discoveries of new and inter- 

 esting double stars to the list of those already known. He made a 

 very large number of measurements upon these objects. New inter- 

 est was manifested by other observatories. The large telescopes of 

 the Lick Observatory, of the observatories of Cincinnati, Madison 

 (Wis.), and Washington, of the Northwestern University, and of 



