228 /. D. Hague on the Guano Islands of the Pacific Ocean. 



In some parts of the deeper deposit a light scale or crust has 

 formed over the surface, which is generally very thin though 

 occasionally hard pieces are found varying from half an inch to 

 an inch in thickness. The thin scale is met with particularly 

 where there is, or has been, any moisture, and, after showers, 

 where pools of water have been standing for some time, such a 

 crust appears on drying. There seems to have been a similar 

 process in the formation of the thicker crust, for it is found only 

 occasionally in places of which the dampness and general appear- 

 ance indicate that water may have assisted at its formation. 



The thinner pieces are found not only on the surface, bat m 

 certain localities form strata at various depths, usually about 

 an inch apart, with intermediate layers of guano. These strata 

 seem to have been formed at intervals during the accumulation of 

 the guano deposit each one at some time having itself formed the 

 surface and now marking a period in its age. 



Each of the localities where these strata occur, although on 

 opposite sides of the deposit are at the edges and immediately 

 adjoining the marginal ridge already described and from their 

 proximity to the shore it seems possible that these may have been 

 subjected to occasional floods by high seas washing over the 

 crown of the beach. 



The following is an analysis of a thick and hard piece of crust 

 found on the surface : — 



Loss by ignition (water and little organic matter) ll-'?500 



Magnesia. . 



Phosphoric acid 

 Sulphuric acid, 



The small amount of magnesia and the excess of sulphuric 

 acid are points worthy of notice. 



This crust is formed on Baker's Island only to a limited extent, 

 but its existence there and character are interesting when com- 

 pared with the Jarvis Island deposits, the better part of which J 

 all crust and in which, as Johnson and Leibig have observed, 

 much of the phosphoric acid is combined as the neutral PD<5' 

 phate of lime. The same is true of this crust of Baker's Isiana- 



Before referring to the climate, birds etc. of this island, I ^^ 

 first give some description of Rowland's and Jarvis' Islands. 



Rowland's Island.— Ahont forty miles in a north northwest 

 direction from Baker's, is situated Rowland's Island in lat i>^ 

 north and 176° 32' west from Greenwich. It is about a mile and 

 a half long by a half mile wide, containing above the crownoi 

 the beach, an area of some 400 acres. The highest point is seven- 

 nT?>, V l^°T ^^" "^^^ ^^^ t«^ o^ twelve feet above the leve 

 ot the high tide. It trends N.N.W. and S S E. The ge^^ 



