TUTTLE ENGINEERING NOTES ON HAWAII. 



137 



and richer soil and a less broken surface for development than does 

 the uplands. 



The small streams which form on the mountain tops are usually 

 dissipated in the porous formation before they reach the sea, and the 

 larger ones have cut gulches with very steep sides and with depths 

 ranging up to over 2 500 ft. While the uplands have the advantage 

 of increased rainfall, they lack the evenness of surface, the desirably 

 higher temperature for growing crops, the richness of soil, and the 

 facilities for transportation and shipment of the lowlands. 



If the surface were less porous, and stream flow were in surface 

 channels, irrigation could be readily and cheaply resorted to and the 

 conditions for agricultural development would be ideal. In most in- 

 stances the irrigation supplies are obtained from sub-surface sources 

 and from depths ranging up to 800 ft. below tide. 



Owing to lesser age it would naturally be expected that there 

 would be a decrease in richness of the soil in the islands toward the 

 south, and as a matter of fact there are large tracts of undecomposed 

 bare lava rock on Maui and Hawaii. 



The exports for the year ending June 30th, 1901, and their value, 

 were as follows: 



The valuable forests of sandal wood, which first opened up the 

 island trade, were almost wholly cut off early in the century. The 

 table shows that the wealth of the island lies entirely in its agricul- 

 tural resources, and that the culture of sugar cane is the most im- 

 portant industry. 



The Sugar Industry. There are 55 sugar plantations on the islands, 

 each having areas under cultivation ranging in size from 300 to 12 000 

 acres, and probably aggregating between 175 000 and 200 000 acres. 



