PLASKETT TELLS SECRETS OF SKY Lecturer to Astronomical Society Talks of Mysteries of Nebulae Strange secrets of the stars and facts about "nebulae," formed queer the foundation of an interesting adwhich H. H. Plaskett of the dress Dominion Astrophysical Observatory, delivered before the Royal Astronomical Society branch of this city last night at College. After a brief survey of 'historical work on nebulae, the lecturer plunged into the known facts of the nearer mysteries of these heavenly bodies, many thousands dis of which known to science. The lecturer told some interesting facts concerning these nebulae. For instance, 570,000 cubic miles of the Orion nebula would weigh just one ounce! Slides from recently-taken Mount Wilson photograps showed the three principal types, the bright diffuse nebulae, the dark diffuse nebulae and the planetary nebulae, which were most numerous in the heavens. The lecturer proceeded to disclose the empirical relations between the temperatures of the stars associated with these different types of nebulae, and the kind of light the nebulae themselves emitted. The second the lecture dealt with the Zanstra and Eddington theories, concerning, these facts. He associated star excited the nebulae to give forth its light, and various terrestrial analogles were cited.