SECTION X. 



OF STEAM NAVIGATION. 



593. ON the value of the application of steam to impel vessels, it has become 

 unnecessary to say more than that its employment is extending rapidly at almost 

 every place on the globe where the trade is considerable, and that its use is limited 

 only by its yet imperfect state. If we had intended to have confined our researches 

 to the mere application of an engine to a vessel already constructed, our labour 

 would have been short, and easily completed : but the construction of vessels is 

 a subject which is capable of improvement ; and while we think there is a power 

 in science to indicate the steps by which it may be improved, it is our duty to 

 submit it to the reader. 



The forms of vessels for stability, speed, capacity, and strength ; the kinds of 

 vessels for different purposes, the resistance, and modes of propulsion ; the nature 

 of the engines adapted for vessels, the strength of their parts, and the species of 

 fuel, and its management to obtain the best effect ; are all objects of importance, 

 and each of these we propose to consider. 



These inquiries are equally applicable to mercantile and to government pur- 

 poses, but there is yet another portion of the subject to which it would be desirable 

 to direct attention. 



In the case of war, steam boats will become a means of attack ; therefore it ought 

 to be considered how far they may become a means of defence, the power of 

 resisting being the best guard against a mode of attack, which will deprive us of 

 many of the advantages of our insular state. Hence, the construction of gun boats 

 for the defence of rivers, and of river navigation, and harbours, would be a proper 

 subject for inquiry, if our limits did not forbid it. 



OF THE FORMS OF VESSELS FOR STABILITY, SPEED, CAPACITY, AND STRENGTH. 



594. In considering the properties of a vessel, the orderly arrangement of our 

 subject requires that we should treat, First, Of stability, or the power a vessel 



