ON THE APPARENT FIGURE OF STARS. ]Q3 



crystallines of a man of forty had their vertical diameter 10m. 

 [3-934/.]. and their horizontal diameter g'6m. \^'777l^. The 

 yellow crystalline of an old man had a vertical diameter of 

 9'25m [3-639/.], a"d a horizontal diameter of 875m. 

 [3-44'/]. The second crystalline was not measured, because 

 it appeared to have had its shape altered. 



The two crystallines of an ox had a vertical diameter of Those of the 

 ig-iz-^m. [7-5341.], and a horizontal diameter of \Q-75va.°^^^^^'^^^^' 

 [7'377l-]- That of a sheep had a vertical diameter of 17'35 m. 

 [6-8261.], and a horizontal diameter of 1 7 m. [6 6881.]. 



These observations, made by Dr. Chaussier, Mr. Ribes, and 



myself, prove, that in the human crystalline the vertical axis 



is longer than the horizontal ; and, consequently, that the two The surfaces 



surfaces, the anterior and posterior, are generated by different ^°^^^^ °' """ 

 r ' e> J lerent curves, 



curves, among which those that are vertical have a greater 

 radius of curvature than those that are horizontal. 



The curve of several of these crystallines appeared to us a and apparent- 

 little irregular. The diameter measured in various directions y,'" "*' 



gular. 

 seemed to be different from those an ellipsis should have had j 



but the differences were not considerable enough to be deter- 

 mined accurately with the compasses which we used for measur- 

 ing the diameters; 



vSince the curve formed by the planes of the anterior and The crystal- 

 posterior segments of the crystalline is not a circle, it follows, ,''"^ conse- 

 that their surfaces are not spherical j and hence, that the rays produce rays: 

 of light passing through them must have as many different 

 foci, as we can conceive osculatory radii to have been em- 

 ployed in generating their surfaces. Thus the crystalline alone, 

 from the irregularity of its surfaces, is capable of producing 

 wholly, or in part, those irradiations, which are perceived on 

 looking at very remote lights. 



The surface of the cornea too, appearing not to be an exact but the cornea 



segment of a sphere, must contribute to the production of new *^°°^"''"'" '" 

 ^ . , . . ,. . rr-, , . the phaenome- 



foci, whence arise new irradiations, Ihus every thmg appa- non. 



rently concurs to refer the production of the irradiations per- 

 ceived from remote luminous objects seen under a very small 

 angle to the combined actions of the crystalline and cornea, that 

 is, to the nature of their curved surfaces. 



From the facts here recited it follows : 



1. That the figure of luminous objects within the sphere of General con- 

 distinct vision is perfectly distinguishable. 2. That clusiom. 



