3§7

Appendix II.

before proceeded to M) be now refractedinto HP, and the Ray A V will at K berefracted into K Z; draw the Line IL andit will intersect the Ray H P in X, and XZwill be the image of the Object B f. Allthis we have demonstrated in the OpticalLecture.

Let this Image be viewed by the Eye-Glass U S, whose focal Distance T Z orT P may be such that the Ray H P may benow a second Time refracted at U intoU Qj parallel to MO or L P draw T X,which will also be parallel to U Q ^ thenWill the Image Z X, or rather the Part ofthe Object B f, be seen under the AngleT QJJ equal to M O P, as at first.

Now it is evident, that were the GlassU S alone by itself, the Indistinctness ofVision would be inversely as T Q^, for thatWould then be the focal Distance of theGlass; but now this Glass TU, in Com-position with the other Lens H I, Ihewsthe same Image under the same Angle andAperture with the focal Distance T P ; theIndistinctness of Vision therefore now willbe inversely as T P, or in other Words,the Distinctness of Vision in the first Cafeby a single Glass will be to the Distinct-ness of she Glasses in Composition as Tto T P, or the Image will appear so muchCc 2 distincter