BIBLIOGKAPHY OF HERSCIIEL's WRITINGS. 595 



Herschel, W.: Synopsis of the Whitixgs of— Continued. 



A. D. Vol. P. 



1809 99 294-2ft3 LI. A Lens maij he looked upon as a Prism bent round in a circular' Form. 



299-302 LII. The critical separation of the Colours, which takes place at cer- 

 tain Angles of Incidence, is the primary cause of the Xewtonian col- 

 oured Rings between Object-glasses. 



300-301 A comparison of the similarities presented by the phenomena of 

 the rings and tliosc of the bows, modified by a reHecting i>late in 

 contact willi the etfective surface of the prism. 



302 LIII. lieniarks rclalinq to the Xewtonian alternate Fits of easy Reflection 

 and easy Transmission. 

 [Dated] Slough, near Windsor, December 9, 1808. 

 Plates XII, XIII, XIV. 



1810 100 149 Supplement to the First and Second Fart of the Paper of Experiments for 



Investigating the Cause of Coloured Concentric Rings between Object- 

 glasses, and other appearances of a similar nature. By William 

 Herschel, LL. D., F. R. S. Read March 1.5, 1810. 



149-150 A statement of the object of this supplement, and a discussion of 

 the distinctions between the red and blue bows. 



151-153 LIV. Supplemenial Considerations, which prove that there are tico 

 primary prismatic Botes, a blue one and a red one. 



154-157 LV. Illustration of the Dependence of the Streaks of both Roivs upon 

 the critical Separation. 



157-159 LVI. Illustration of the dependence of Rings, seen in a Prism, upon 

 the critical Separation. 



159-161 LVII. Ixcmarks on Colours supjyosed to be produced by thin Plates 

 or WeTlges of Air. 

 A repetition of the experiment of the 39th Article slightly modified. 

 Two slips of plain glass touching at one end were separated at the 

 other by a single fibre of silk. It is concluded that the phenome- 

 non of coloured streaks seen near the lino of contact is so well 

 accounted for by the 35th Article that it would not bo philosophi- 

 cal to ascribe them to plain surfaces. 



161-163 LVIII. Illustrating Remarks on the Intention of the lAth Figure, ex- 

 plained in the 48th Article of my Paper. 



164-166 LIX. Experiments on the multiplying Power of Surfaces, in contact, 

 which modify the form of prismatic Appearances. 



166-168 LX. Of the breadth of the Streaks compared to that of the Bows, and 

 the cause why they must take up a broader space than the Bows from 

 which they are derived. 



169-177 LXI. Of the Manner in tchich Rays that are Separated by critical re- 

 flection or Intromission come to the Eye. 

 Plates V, VI. 



1811 101 269 Astronomical Obserratims relating to the Construction of the Heavens, 



arranged for tlie purpose of a critical examination, the result of which ap- 

 pears to throw some new light on the Organization of the Celestial bodies. 

 By William Herschel, LL. D., F. R. S. Read Juno 20, 1811. 



332 "Synopsis of the Contents of this Paper." 



[The following analysis is by Herschel himself and has served as a 

 model to us. ] 



272 Diffused nebulosity exists in great abundance. 



275 Observations of more than one hundred and fifty square degrees of it. 



277 Its abundance exceeds all imagination. 



Nebulous matter consists of substances that give out light, which may 

 have many other properties. 



