164 GOODYEAR ON GUM-ELASTIC. 



Still more buoyant by the addition of compartments. See plate 

 , %. 

 For further descriptions of a variety of portable boats and 

 portable life-boats, see Chapter 



BALLAST TANKS. 



It is suggested that an important improvement may be made 

 in the method of giving ballast to boats and vessels, by the use 

 of large tanks made of caoutchouc fabrics, to be placed in the 

 bottom of the vessel or boat. 



These bags may be so arranged with connecting hose, that 

 the water may be pumped in and out. At the same time the 

 fresh water of the vessel may be taken in these tanks, instead of 

 being taken in hogsheads, in which case it is apparent there 

 would be a great saving of room and labor. 



