Manchester Memoirs, Vol. lix ( 1 9 1 5 ), No. \%. 33 



Sheet 48. 



(20J" X 1 6 1".) This has four diagrams : — 



(1) The concentration of a parallel beam by a 



double convex lens to its principal focus. 



(2) The method of use of a double convex lens as 



a magnifying glass. 



(3) The formation of an inverted magnified real 



image by a double convex lens. 



(4) The formation of an image by a double concave 



lens. 



Sheet 49. 



(2i"xi7".) The upper diagram explains the com- 

 pound microscope. Three convex lenses are used to 

 produce a magnification of an insect. The lower diagram 

 relates to the solar microscope. Sunlight is reflected by 

 a mirror and concentrated by a large convex lens on an 

 insect. With the aid of a small convex lens of short focal 

 length an enlarged image of the insect is produced. 



Sheet 50. 



(2i|"x i7\".) This has five diagrams, explaining the 

 optical principles of: — 



(1) The Gregorian reflecting telescope. 



(2) The common refracting telescope with erecting 



lenses. 



(3) The refracting astronomical telescope with four 



lenses. 



(4) A telescope with two convex lenses. 



(5) The opera glass. 



Sheets 51 and 52. 



The first is a small diagram (10" X 8") showing how 

 an inverted image is produced on the retina of the 

 eye. The other sheet (21" x 17") shows the previous 



