The Observatory has nearly completed its arrangements for observing the total eclipse of the sun on May 28. The object of this observation is to discover whether a body exists between Mercury and the sun. For the observation a photographic instrument has been constructed which will take pictures of stars of the eighth magnitude at the time of eclipse. Three weeks ago this instrument was sent to Washington, Georgia, the site selected for observing the eclipse, and it is now being mounted there. On Monday Professor Pickering will start South to complete the preparations. He will be accompanied by Mr. J. Rayner Edmands, who selected the site, and by Mr. Attwill, who will take the photographs. A few days before the eclipse and additional party from the Observatory will go to Washington to assist Professor Pickering in making the observations.