The Calculation of Axisymmetric Duct Geometries for Incompressible Flow with Hagen-Poiseuille flow and Modelling Body Forces

A sight-facilitating apparatus is provided capable of providing magnifications of about 4X to 8X in an aesthetically pleasing manner. An elongated casing has a light entry at one portion thereof and a light exit at an opposite portion thereof. A prismatic telescopic lens system including an objective, an ocular, and the like is mounted within the casing so that light entering the casing throught the light entry passes through the lens system and exits the light exit, with provision for adjusting the focus of the lens system. The objective is mounted within the casing so that the majority of the focal length thereof extends parallel to the direction of elongation of the casing, the light from the first optical element of the lens system being directed along the direction of elongation of the casing. The casing is preferably mounted on top of or incorporated into an eyeglass frame, between the ear pieces, so that the direction of elongation of the casing extends substantially horizontally between the wearer's eyes, with the light exit adjacent a wearer's eye. The wearer may look through the eyeglass lenses and then by tilting his/her eyes with respect to his/her head an angle of about 10 DEG , look through the light exit.