Description of the Carnegie 



161 



of the main boom. The distance from the forward end of the bowsprit to the 

 forward end of the load water-hne is 48 feet; from the forward end of the load water- 

 line to the foremast 35 feet; from the foremast to the mainmast 48 feet. The rigging 

 is of Russian hemp. Figure 8 shows the sail plan. (See also Plate 7, Figure 3, 

 Plate 8, Figure 1, Plate 15, Figure 1, and Plate 17, Figures 2 and 5.) 



It was decided to install auxiUary propulsion for use in entering or leaving ports 

 and to prevent interruptions in the observations b}^ maintaining desired headway 

 during calms. The necessity of providing auxiliary propulsion which would be 

 nearly non-magnetic in character made the selection of the type of the plant a 

 rather difficult matter. Steam was precluded on account of the necessarily high 

 magnetic nature of a steam plant. The only type of prime mover at the time 

 (1909) which could be economically built and maintained in reliable operation with 

 a minimum of non-magnetic metals in its construction appeared to be an internal- 

 combustion engine. (See PI. 8, Figs. 2-5.) 



Fig. 8. — Sail Plan of the Carnegie. 



Consideration of the available fuel for such a motor resulted in the elimination 

 of gasoline or oil, not only on account of cost, but also because they would be usually 

 unavailable in the zones to be covered by the Carnegie, as well as dangerous in the 

 quantities which would have to be stored for the lengthy voyages contemplated. 

 A careful investigation showed that a gas-producer for marine purposes could be 

 built which would generate from anthracite coal a suitable gas for use in internal- 

 combustion engines and that such a plant could be constructed almost entirely of 

 non-magnetic materials. The suction type of gas-producer was adopted, principally 

 because of its simplicity in construction and operation and on account of eliminating 

 as much as possible other auxiliary apparatus. 



