Within a year aerial navigation has emerged from the realm of theory and speculation as a practical, though still undeveloped, commercial and war-time asset of marvelous possibilities. As recently as a year ago, when Mr. H. H. Clayton of the Blue Hill Observatory spoke in the Union on "Aerial Navigation," the names of the Wright brothers were the only ones generally known in connection with the subject; today dozens of men with several types of machines are solving in two continents the problems of man's flight. The conquest of the air by balloon and aeroplane will be in this age what the mastery of land and water by steam was in the last generation.

This evening an opportunity will be given to members of the Union to hear about man's triumph over the air from Professor Rotch, whose work in establishing and maintaining the Blue Hill Observatory has contributed much to our knowledge of atmospheric conditions. He is an authority on the subject whose lecture will be instructive and entertaining.