574 BIBLIOGRAPHY OF HERSCHEL's WRITINGS. 



Herschel, W.: Synopsis of the Writings of— CoDtiuued. 



.4.. D. Tol. P. 



they arc the same or different. By William Herschel, LL. D.,F. R. S. 

 Part II. Read Nov. (5, 1800. 

 "The next three articles of this paper will require, that while we 

 shew the similarity between light and heat, we should at the same 

 time point out some striking and substantial differences, which will 



1800 90 438 occur in onr experiments on the rays which occasion them, and on 

 which hereafter we may proceed to argue, when the question re- 

 served for the conclusion of this paper, whether light and heat be 

 occasioned by the same or different rays, comes to be discussed." 

 Art. IV. Different EefrangibiliUj of the Bays of Heat. 



439 Construction of a curve, from experiments before described, the ab- 



scissas of which represent the arrangement of colours in the pris- 

 matic spectrum, and the ordiuates the corresponding luminous in- 

 tensity. 



440 Construction of a curve which, in a similar manner, represents the 



distribution of heat in a j)rismatic spectrum. 

 ''A mere inspection of the two figures, which have been drawn as 

 lying on each other, will enable us now to see how very differently 



441 the prism disperses tbe heat-making rays, and those which occasion 

 illumination. * * * These rays neither agree in their mean 

 refrangibility nor in the situation of their maxima." 



441-442 21st Experiment. The sines of Befraction of the heat-makitig Bays are 

 in a Constant Batio to the sines of Incidence. Ten different refracting 

 angles of various media were used. 



443 22nd Experiment. Correction of the Different Befrangihility of Heat hy 



contrary Befraction in Different Mediums. An achromatic combina- 

 tion of two crown prisms and one flint deflected no heat outside the 

 visible spectrum. 



444 23rd Experiment. Li Burning-glasses the Focus of the Bays of Heat is 



Different from the Focus of the Bays of Light. 



445 Art. V. Transmission of Heai-maJcing Bays. 

 446-448 Description of apparatus for this investigation. 

 447 [Foot-note.] Theory of the sensibility of thermometers. 



449 Transmission of Solar Heat through Colourless Substances. 



24th Experiment. The transmission of rays by a piece of bluish- white 

 glass measured. 



450 Reference to Table 7 at the end of the paper, which gives the propor- 



tion of light transmitted by various substances, solid and liquid, 

 white and coloured. 



451 25th Experiment. Transmission through a piece of flint glass J inch 



thick. 



452-453 Experiments 26 to 30. Transmission through crown glass, coach 

 glass, Iceland crystal, and two varieties of talc. 



453 Transmission of Solar Heat through Glasses of the prismatic colours. 



453-456 Experiments 31 to 43. 



456 Transmission of Solar Heat through Liquids. 



457-458 Experiments 44 to 49. Transmission through well-water, sea- 

 water, spirits of wine, gin, and brandy. 



458 Transmission of Solar Heat through Scattering Substances. 



458-462 Experiments 50 to 62. Transmission through various pieces of 

 ground glass, an olive-coloured glass, calcined talc, white paper, 

 linen, white jiersian, and black muslin. 



462 Transmission of Terrestrial Flame-heat through various Substances. 



