334 Mr. Harvey's experimental inquiries relative to the 
plans of the upper, middle, and lower decks. The lines a. o', 
A! P, a! p', in fig. 1, are the intersections of the three longi- 
tudinal vertical planes with the surface of the upper deck. 
The first of these planes passes through the principal section 
of the ship ; and the other two are at the equal distances of 
6 feet from it, on the starboard and larboard sid.es of the 
vessel. This distance was selected, because after a careful 
examination of the situations of the principal attractive 
masses on the different decks, it seemed equally removed 
on the one hand from the action of the iron employed in 
constructing the sides of the vessel, and the guns (which 
on the middle deck were trained nearly parallel to the ports ) ; 
and on the other, from the shot arranged round the several 
hatchways, the iron staunchions, and the other masses of 
iron existing in the middle parts of the ship. 
The form of the vessel would not however admit of the 
extension of those planes, through the whole range of the 
lower deck; but at the stations were supposed to 
pass 5 feet on each side of the middle section, as far as the 
line of stations H w x'" hi" ; and from the points E'" e'", to the 
line of stations F" y'f", at the distance of 2 feet and a half. 
The vertical plane therefore which passed through the line 
a! o', produced the section fig. i , Plate XVIII. intersecting the 
middle deck in the line a" x" ; the lower deck in the line 
y" %" ; the iron ballast in 7 rQ; the shot locker in x'" £ <r ; and 
the middle course of iron tanks in r <r v <p- The starboard and 
larboard vertical planes which passed through A' P', alp', 
likewise intersected the middle deck in A" N", a" n " ; the 
lower deck in FT" N'", h'" n'" ; the iron ballast in ; and 
