Lieutenant Commander Richard Byrd has informed the Union that unexpected circumstances will make it impossible for him to speak in Cambridge this evening as was planned. The moving pictures of aeronantical subjects will be run according to schedule and Lieutenant R. D. Thomas will speak in his place.

The cause of the aviator's withdrawal came in the form of a dispatch notifying him of his appointment as commander of the Wilkins Expedition which will try to reach the North Pole next summer. It has not yet been announced what part aeroplanes will play in the expedition but the placing in charge of an experienced aviator makes it appear probable that the attempt will again be made to fly to the Pole. Preparations for the trip are already being started in Washington and it is to supervise the preliminary organization of personnel and equipment that Lieutenant Commander Byrd has been called away. He has agreed to come to the Union some time next fall to tell the story of the summer's expedition.

Lieutenant Thomas, a friend of Lieutenant Commander Byrd, and a big figure in the aviation world will speak in place of the expedition leader during the screening of the aviation pictures. In 1924 Lieutenant Thomas was awarded the Boston Army and Navy Trophy for safe flying. He recently 'established a world record in the annals of flying by spending 700 hours in the air without a single accident of any kind. President Coolidge presented him the Schiff Memorial Trophy, a prize awarded annually to the outstanding flyer of the United States Navy who spends the greatest amount of time in the air without accident.