BIBLIOGKAPIIY OF IIERSCHKL's WKITINGS. o91 



Herschel, W.: Syxoi>sis of tiik Winnxos or— Contiimod. 

 A. D. Vol. 1>. 



1807 U7 180 Expcrimcr.U for inrcsti<]aiiu<i the Cause of the coloured concentric Rings, 

 discorcrcd hj) Sir Isaac Newtox, between two Object-glasses laid upon 

 one another. By William IIekschel, LL D., Y. R. S. Read Feb- 

 ruary 5, 1807. 

 180-181 Introduction. 



182-185 I. Of different inctliod-i to make one net of concentric rings visible. 

 185-186 II. Of seeing Eings by Iransmission. 



187-188 III. Of Shadoics. When two or more sets of rings arc to bo ex- 

 amined they may be distinguished by casting the shadow of a potiited 

 penknift^ upon one set or another. 

 188-193 IV. Of (wo sets of Eings. 

 193-194 V. Of three sets of Eings. 



195 VI. Of four sets of Eings. 

 195-198 VII. Of the Size of the Eings. 



196 VIII. Of Contact. 



197 IX. Of Measuring Eings. 

 197-198 X. Of the Number of Eings. 



198-199 XI. Of the Effect of Pressure on the Colour of the Eings. 

 199-200 XII. Of diluting and concentrating the Colours. When the rings 

 grow wider by using a lens of larger radius, they ai'e said to be di- 

 luted. 

 201 XIII. Of the order of the Colours. 



201-202 XIV. Of the alternate Colour and Size of the Eings belonging to the 



primanj and dependent Sets. Certain of the dependent sets are rings 



by transmission as seen reflected at the back surface of the lower 



plate. 



202-203 XV. Of the sudden Change of the Size and Colour of the Rings in 



different Sets. This is brought about by letting the shadow of 



the knife-blade fall on one or the other set. 



204-20G XVI. Of the course of the Eaijs bg which different Sets of Eings are 



seen. 

 206-207 XVII. Why two connected Sets of Eings are of alternate Colours. 

 207-208 XVIII. Of the Cause of the sudden CJmnge of the Colours. 

 208-209 XIX. Of the Place ivhere the different Sets of Eings are to be seen. 

 209-210 XX. Of the Connection, between different Sets of Eings. 

 211-212 XXI. To account for the Appearance of several Sets of Eings with the 



same coloured Centers. 

 212-213 XXil. Of the reflecting Surfaces. 

 213-214 XXIII. Of the transmitting Surfaces. 

 214-218 XXIV. Of the Action of the first Surface. 

 218-221 XXV. Of the Action of the second Surface. 

 221-222 XXVI. Of the Action of the third Surface. 



222 XXVII. The Colour of the rejlecting and transmitting Surfaces is of 

 no consequence. 

 222-225 XXVIII. Of the Action of the fourth Surface. 



225 XXIX. Considerations that relate to the Cause of the formation of C07i- 



centric Eings. 



226 XXX. Concentric Eings cannot be formed by an allernale Reflection 

 and Transmission of the Eays of Light. 



<'One of the most simple methods of obtaining a set of concentric 

 rings is to lay a convex lens on a plain metalline mirror; but in this 

 case we can have no transmission of rays, and therefore we cannot 



