On the possibility of determining Hubble's parameter and the masses of galaxies from the gravitational lens effect

The gravitational lens effect i applied to a supernova lying far behind and close to the line of sight through a distant galaxy. The light from the supernova may follow two different patbs to the observer, and the difference At in the time of light travel for these two paths can amount to a couple of months or more, and may be measurable. It is shown that Hubble's parameter and the mass of the galaxy can be expressed by At, the red-shifts of the supernova and the galaxy, the luminosities of the supernova "images" and the angle between them. The possibility of observing the phenomenon is discussed.