Page:The sidereal messenger of Galileo Galilei.pdf/35

 method of measuring distances remains for inquiry, and this we shall accomplish by the following contrivance:—



For the sake of being more easily understood, I will suppose a tube. Let be the eye of the observer; then, when there are no lenses in the tube rays from the eye to the object  would be drawn in the straight lines, , but when the lenses have been inserted, let the rays go in the bent lines , ,—for they are contracted, and those which originally, when unaffected by the lenses, were directed to the object , will