L E C T U R E A T K E I O U N I V E R S I T Y 8 5 7 difficult to find cases in which the actual difference could be subjected to observation. As yet, only the following have been found: 1. The distortion of the oval orbits of planets round the sun (confirmed in the case of the planet Mercury) 2. The deviation of light-rays in a gravitational field (confirmed by the Solar Eclipse ex- peditions of 1919 and 1922) and 3. The shifting of spectral lines toward the red end of the spectrum in the case of light coming to us from stars of appreciable mass (not yet confirmed). Concluding, the lecturer touched the age long riddle: Is the universe finite or infinite? The number of stars is finite. To this conclusion Dr. Einstein is led by a series of observa- tions and calculations. Our universe is finite, that is, our world, the world where every body has the three dimensions, length, height, and depth, and time added, but there may be other worlds of other dimensions. The finiteness of our world will be dealt with in Dr. Einstein’s next lecture on the 24th.