PLATE XVI 



Coloured figures illustrating the appearance of the sea, executed by the 

 author during the survey. 



The blue washes in Figs. 5, 13 and 15 illustrate the appearance of the 

 open ocean in sunny conditions, the indigo, Figs. 12 and 14 when 

 overcast : these sketches were made at more than 30 miles from the coast 

 (see below). The green washes, Figs, i, 4, 9 and 10 may be looked upon 

 as normal for the in-shore water : Figs. 2, 3 and 8 as intermediate between 

 the blue and green. The reddish yellow Figs. 6, 7 and n found re- 

 spectively at Pisco, Callao and the Guaiiape Islands are abnormal 

 colorations (see pp. 221-2). 



The colours (Figs. 3, 4 and 14 excepted) represent transmitted light 

 and were obtained by looking down into the water under the overhang 

 of the ship's stern where interference from reflected light is mostly 

 eliminated. In Fig. 12 a swirl of air bubbles produced by the screw is 

 indicated. The importance of avoiding sky reflections is shown in Fig. 4 

 in which surface reflection was blue but the colour of the water in wave 

 shadows was green: compare also Figs. 2 and 12 with the corresponding 

 appearance of the sea surface in Figs. 3 and 14. 



A Table showing date, hour, position and nomenclature of the original 

 observations illustrated in Plate XVI is given in Appendix III. 



