130 THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE 



magnification from 41 to 143 diameters. Instead of the usual bi- 

 convex eye-lens, two plano-convex lenses were applied with their 

 convex surfaces in contact, by which he claimed to obtain a much 

 flatter field. Mr. Mayall found in the Museo Copernicano at Rome 

 a microscope answering so closely to this description that he does 

 not hesitate to refer its origin to Divini. He made the sketch of 



it given in fig. 95. 

 But the optical con- 

 struction had been 

 tampered with and 

 could not be esti- 

 mated. 



Cherubin d'Orleai is 

 published, in 1671, a 

 treatise containing a 

 design for a micro- 

 scope, of which fig. 

 96 is an illustration. 

 The scrolls were of 

 ebony, firmly at- 

 tached to the base 

 and to the collar 

 encircling the fixed 

 central portion of the 

 body-tube. An ex- 

 terior sliding tulte 

 carried the eye-piece 

 above on the fixed 

 tube, and a similar 

 sliding tube carried 

 the object-lens below. 

 these sliding tul x -s 

 serving to focus the 

 image and regulate 

 (within certainlimits) 

 the magnification. 

 He also suggested a 

 screw arrangement 

 to be applied beneath 

 the stage for focus- 

 sing. He devised, or 

 recommended, seve- 

 ral combinations of 

 lenses for the optical 

 part of the micro- 

 scope, and refers to combinations of three or four separate lenses, 

 by which objects could be seen erect, which he considered ' much to 

 be preferred.' 



He also invented a binocular form of microscope and published 

 it in his work, ' La Vision Parfaite,' in 1677. It consisted of two 

 compound microscopes joined together in one setting, so as to be 



FIG. 96. Cherubin d'Orleans' compound microscope 



(1671). 



