50 



them 



wh 



observed th 



paper took the curvatui 



of 



a 



rainbow: from the upper edge proceeded shades of red-brown, 

 terminating in yellow, and from the lower edge shades of 



grey, terminating in bl 



as 



have shew 



d sketch 



Th 



IS 



observed und 



at (C) 



th 



e an- 



various light 



marked, that before sun-rise no red appeared in the b 



re- 



no violet 



same tints which 



th 





use 



always 



use for my foregrounds 



distances a cold 



grey, 



grey shades; but they were exactly the 



in shading and finishing my sketches. 



for iny 



warm brown 



or neutral tint 



colour 



afterwards 



and these two tints 



ver the whole with colour; and these two tints exactly coin 

 de wrth those shewn at (C), where a broad mass of white ap 



exactly 



peared betwixt them 

 that I could contract this white space 

 " e sun began to illumine the horizon 



th 



upper edge, and violet in the low 



By gently turning the prism 



j shewn at (B) 

 I perceived 



found 



as 



in th 



e 



by gently turning the prism a little more, I 



en the rainbow 



but no green appeared, till 



and yellow into contact, wl 



ue 



all its colour 



as represented at (A) 



I the 



t ,, .. r — *--«.:-VfV- itnencon 



I could avad myself of this discovery to facilitate th 



process of printing * n A ~a^ < 



brought the 

 was completed in 



sidered how 



of printing and colouring 



mechanical 



make a fac-simile of 

 explain by the 

 to represent th 



m y sketches 



annexed 



many thousand plates, 



hall endeavour 



to 



th 



e same 



before 



d after th 



two Landscapes, which 

 ene before and after 



to 



are 



natural process of colo 



ipposed 

 that is. 



I he t«d,ght scene is finked with th 



harmonizing wash thrown 



uring takes 



two neutral ti nts 



over the whol 



and 



e ; the other is also 



