Dr. Young’s Remarks on the 
304 
that objections to the application of those arguments or experi- 
ments, which may occur at first sight, may be capable of being 
removed by a more minute investigation : and the importance 
of the subject requires, that no assistance, which can be afforded 
by the abstract sciences, should be withheld from the service 
of the public, even by those who have no professional motives 
for devoting themselves to it. 
2. Forces acting on a Ship. 
The first consideration that is necessary, for enabling us to 
judge of the propriety of any arrangement respecting the 
construction of a ship, is to determine the nature and magni- 
tude of the forces which are to be resisted ; and the second, to 
inquire in what manner the materials can be arranged, so as 
best to sustain the strains which these forces occasion. The 
principal forces, which act on a ship, are the weight of the 
whole fabric with its contents, the pressure of the water, the 
impulse of the wind, and the resistance of the ground or of a 
rock : and we must endeavour to ascertain the degree in 
which any of them have a tendency to bend the ship longitu- 
dinally or transversely, or to break through any part of her 
texture ; and to inquire into those causes, which are likely to 
promote or to obviate the decay of the substances employed. 
3. Causes of archings W eight. 
It is unnecessary to explain here the well known inequa- 
lity of the distribution of the weight and pressure, which causes 
almost all ships to have a tendency to arch or hog, that is, to 
become convex upwards, in the direction of their length. It 
is possible that there may be cases in which a strain of a very 
