R. M. Petrie To Speak On Stars The first meeting of the Astronomical Society this season will be held on Thursday at Victoria College and will de addressed by R. M. Petrie, M.A., who o is spending the summer at the Dominion Astrophysical Observatory. Mr. Petrie has spent the last three years studying at the University, of Michigan, where he has distingushed scholastic record. The subject of the meeting will be "Astronomical Instruments," and the lecturer will explain the principle of the powerful but intricate apparatus used by astronomers in studying the stars. Instruments described by Mr. Petrie the powerful reflecting and refracting telescopes, of which the Victoria reflector 1s one of the finest, as well as apparatus, such as the spectroscope, interferometer and photometer. During the last few years many very intricate and delicate devices have perfected for the purpose of measuring the light and heat of the stars. These include a radiometer with waves made from flies' wings, the phothe cell, the The bolometer principles and the involved in the use of these devices will be explained by the speaker who will illustrate his remarks by lantern slides. After the lecture an opportunity will be given for members of the audience to view the moon and the planet Saturn through a four-inch telescope. The meeting is open to the public. I