CAPE OF GOOD HOPE. 467 



who are employed in the quarries to furnish stone for paving and 

 building. The stone is a schistus, and commonly known at the 

 Cape as blue flag. 



As we cleared the island, objects to seaward were seen refracted in 

 a manner that I had never before observed so distinctly. As before 

 stated, there was an upper and an under current in the atmosphere, 

 and these strata were of different temperature. The thermometer at 

 the masthead marking 73°, while that on the deck stood at no more 

 than 59°. A ship about three miles distant in the offing, was seen 

 vertically and horizontally ^refracted at the same time. Her courses 

 and topsails appeared ill-defined, shapeless, and quivering; her bow- 

 sprit and head-spars formed curves, while her jib and flying-jib were 

 drawn out into horizontal lines. Above, her topgallant-sails and 

 royals were seen perfectly well defined ; a distinct line of bluish haze 

 divided them from the lower sails, and could be traced to about sixty 

 degrees on each side, until it joined with the horizon. 



A signal made by this ship at the time, showed in faint colours, as 

 if flying from her peak and fore-topsail-yard 

 at the same time. The annexed wood-cut, 

 from a sketch made at the time, will give a 

 better idea of this appearance. 



The angle subtended between the line 

 of haze and the horizon, was twenty-five 

 minutes. 



The temperature of the water was often tried : it was found to stand 

 at about the same temperature as when we entered on soundings, 

 varying little from 64°. After running off about thirty miles from 

 the coast, the temperature of the air rose to the same point. 



On the 19th, Joseph Sylva (boy), died of phthisis. He had been 

 long lingering, and was apparently affected with the disease when 

 taken on board at Oahu, a few months previously. 



We now shaped our course for St. Helena, which I was desirous 

 of reaching at the earliest day, in order to intercept the two brigs, 

 and if a further supply of bread could be obtained there, to proceed 

 with them directly for the United States. 



Our passage to St. Helena was of the ordinary length, thirteen 

 days ; we had very light winds and a smooth sea, indicating that 

 a long calm had existed. Northerly currents generally prevailed, 

 though at times setting to the eastward and westward of that point. 

 On the 30th of April, in the latitude of 23° S., and longitude 



