BIBLIOGRAPHY OF IIERSCHEL's WRITINGS. G17 



Subject-Lndex. Pmi-OsopuiCAT, TuANSACTioss. Tear Pace 



Nebulous stars: ^^^,^2 ^^^^ 



777= 1814 2o5 



Nebulous strata : tlicir origiu 17^- 2:a 



Newtox: '""!!!! 1705 '^e 



Newton's riugs : iu general 1^07 1^0 



'• lf<m 259 



= IslO l-l'J 



Nucleus of a Comet : (lefinitiou IkOS 1-16 



Oheroii : discovered Jan. 11, 1787 (period V.U days) 171-7 126 



: its elemeuts 17^3 \ ^^^ 



I 377 



; is brighter than Titania 17fS3 ^57(3 



: is variable in brightness ISlo 356 



: revolves in 13'^ ll^^ 8™ 59' 1815 :{50 



Observations: are made to jihilosophize upon, and to communicate 1784 438 



: 1785 213 



: practical hints for observing. See Methods of observing. 



Olbers: 1^07 200 



Optical illusion in viewing the moon 1795 53 



Orion : the trapezium is not connected with the nebula 1791 77 



Pallas : observations 1802 213 



: its diameter is 147 miles. 



Parallactic motions : of stars in general 1805 233 



Parallax of the Sun, Stars, etc. : see Sun, Stars, etc. 



Perihelion passage of a Comet : its effect 1812 140 



: 1812 235 



Periodicity of Solar Spots: is connected with the price of wheat 1801 310 



Phases of Comet 1807, I 1808 156 



Photometry: Table of the transmission of terrestrial scattered light 



through various substances, etc 1800 528 



: 1800 533 



: 1800 534 



Photometry of Stars : methods 1806 208 



: See Catalogues of the Comparative Brightness, etc, 



Pigott: 179G 177 



Planetary Nebulas 1802 501 



Planets : all are probably self-luminous to some degree 1795 50 



: defined 1802 224 



: their evolution 1812 143 



Pores: in the Sun 1801 292 



Price of wheat : its connection with Sun spots 1801 310 



Probable errors : see Errors. 



Proper motions : of nebulae 1814 249 



Proper motion : of the sun, stars, etc. See Sun, Stars, etc. 



Proper motions of Stars : their cause 1806 225 



Radiant Heat: see Heat. 



Red Stars : see Stars. 



Reflecting telescopes : see Telescopes. 



RefrangibiUty of heat, etc. : see Heat. 



Resisting medium I'^l 1^'' 



: may stop some light l'^~ ^'^^ 



Resolution of the milky way, etc. : see Milky Way. 



