The Mangrove Shields of the Savages 



The implements were crude but the 

 product was serviceable and artistic 



A scar left on a mangrove tree from 

 the tearing away of bark for a shield 



IN the days when the savages 

 of the New South Wales coast 

 fought with spears and boom- 

 erangs, a stout shield was an im- 

 portant part of the warrior's 

 equipment. White men, with 

 their firearms and their tools of 

 steel, had not yet arrived. The 

 Stone Age had not given place to 

 the Age of Iron. 



Nobody knows when the first 

 enterprising native discovered 

 that the gray mangrove tree could 

 be made to yield a shield of un- 

 rivaled toughness by a compara- 

 tively simple operation. This con- 

 sisted of cutting through the bark 

 of the trunk an oval groove, or 

 rabbet, two or three inches deep. 

 Into this groove were inserted a 

 number of wedges made from a 

 special kind of stone. By driving 

 these wedges in with a stone ham- 

 mer, a layer of wood was brought 

 away in a single piece; then a little trim- 

 ming and the attachment of a bit of 

 twisted vine sufficed to convert the piece 

 into a perfect shield. 



In the Port Macquarie district almost 

 every gray mangrove tree of suitable size 

 has been made to yield such a shield, and in 

 many cases two or more shields have been 

 taken from one trunk. The conspicuous 

 scars remain to tell the story of a vanished 

 art. Some of these scars are believed to be 



The perfect shield, 

 trimmed, polished 

 and provided with 

 a handle made of 

 twisted vine tendrils 



Driving the stone edges in around 

 the oval piece of bark marked off 



more than five hundred years old, 

 while some are relatively modern, 

 and were made with steel axes. 



The earliest English shields 

 were "bucklers" of lindenwood 

 and were made in much the 

 -ame manner as these mangrove 

 shields of the savages, except 

 that they were provided with 

 strong iron ribs and bosses. 



Throwing Heat Overboard 

 from Ocean Steamers 



O^ 



N all sea-going steamers, the 

 steam is condensed by sea- 

 water pumped through the surface 

 condensers. This circulating water 

 is then discharged overboard. In 

 the process of condensation, the 

 cooling water taken in at tempera- 

 tures varying from 32 degrees to 88 

 degrees Fahrenheit according to 

 climatic and other conditions, is raised to 

 •temperatures varying from 80 to 120 de- 

 grees and then discharged. This great loss 

 of heat is practically unavoidable. Even on 

 comparatively small steamers, hundreds of 

 tons of heated water are pumped overboard 

 daily. This constitutes one of the greatest 

 heat losses in the operation of steam ma- 

 chinery, although sometimes a portion of 

 the warm water is used for scrubbing decks 

 and for bath water on passenger ships. 



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