302 PERNAMBUCO, BRAZIL. 



an workmen. On this coast the currents of the sea 

 tend to throw up in front of tlie land long spits and 

 bars of loose sand, and on one of these part of the 

 town of Pemambuco stands. In former times, a 

 long spit of this nature seems to have become con- 

 solidated by the percolation of calcareous matter, 

 and afterwards to have been gradually upheaved, 

 the outer and loose parts during this process having 

 been Avorn away by the action of the sea, and the 

 solid nucleus left as we now see it. Although night 

 and day the waves of the open Atlantic, turbid 

 with sediment, are driven against the steep outside 

 edges of this wall of stone, yet the oldest pilots 

 know of no tradition of any change in its appear- 

 ance. This durability is much the most curious 

 fact in its history : it is due to a tough layer, a few 

 inches thick, of calcareous matter, wholly formed 

 by the successive growth and death of the small 

 shells of Serpulae, together with some few barnacles 

 and nulliporae. These nuUiporaj, which are hard, 

 very simply-organized sea-plants, play an analogous 

 and important part in protecting the upper surfaces 

 of coral-reefs, behind and within the breakers, 

 where the true corals, during the outward growth 

 of the mass, become killed by exposure to the sun 

 and air. These insignificant organic beings, espe- 

 cially the Serpula?, have done good service to the 

 people of Pernambuco ; for without their protect- 

 ive aid the bar of sandstone would inevitably have 

 been long ago worn away, and without the bar 

 there would have been no harbour. 



On the 19th of August we finally left the shores 

 of Brazil. I thank God I shall never again visit a 

 slave-country. To this day, if I hear a distant 

 scream, it recalls with painful vividness my feel- 

 ings, when, passing a house near Pemambuco, I 

 heard the most pitiable moans, and could not but 



