Recent Progress in Boundary Value Problems on Lipschitz Domains

The invention is an improvement in the construction of a penetrable target screen comprised of an adjacent series of narrow parallel strips of tape so mounted as to permit target images to be projected thereon and the passage therebetween of an object propelled at the target. The improved screen is comprised of a relatively small number of individually mounted broad tape sections, which sections are slit providing a multitude of adjacent narrow parallel strips supported by common end portions between which a projectile may pass. Stiffening pins are located in cylindrical pockets at the ends of the broad tape sections. Tension springs connect the stiffening pins to a supporting frame. The broad tape sections slightly overlap each other and bear against strips of low friction material provided on two parallel spaced apart upright supporting members.