204 Mr. Atwood's Disquisition on 
retard the progress of naval architecture, by increasing the 
hazard of failure in attempting to supply its defects by expe- 
riment j for, when no satisfactory estimate can be formed 
from theory, of the effects likely to ensue from adopting any 
alteration of construction that may be proposed, doubts must 
necessarily arise respecting its success or failure, which can be 
resolved only by having recourse to actual trial : a species of 
experiment rarely undertaken under the impressions of uncer- 
tain success, when the objects of it are so costly, and otherwise 
of so much importance. To the imperfections of theory, may 
also be attributed that steady adherence to practical methods, 
rendered familiar by usage, which creates a disposition to re- 
ject, rather than to encourage, proposals of innovation in the 
construction of vessels : the defects or inconveniences which 
are known, and have become easily tolerable by use, or may 
perhaps be the less distinctly perceived for want of comparison 
with more perfect works of art, being deemed preferable to 
the adoption of projected improvements, attended by the dan- 
ger of introducing evils, the nature and extent of which cannot 
be fully known. These are amongst the difficulties and dis- 
advantages which have concurred in rendering the progress of 
improvement, in the art of constructing vessels, extremely slow, 
and have left many imperfections in this practical branch of 
science, which still remain to be remedied. In respect to the 
theory of vessels, it would be giving that term too narrowed 
a meaning, to consider it as derived solely from the laws of 
mechanics ; every notion or opinion which may be applied to 
explain satisfactorily the phenomena depending on a vessel's 
construction and qualities, so as to infer the consequences of 
given conditions, independently of actual trial, whether it ori~ 
