distribution, &c. of the magnetic intensity in ships of war. 317 
in corresonding positions of the ship's head, as recorded in the 
following table. 
Variations of Intensity from Upper to Lower Deck. 
Direction of the 
Ship’s Head. 
Larboard 
Section. 
Middle 
Section. 
Starboard 
Section. 
Mean of the 
three Sections. 
North, 
4- 1.26 
— 0.8 9 
2.68 
O.76 
East, 
— 12.64 
4 1-79 
+ 13.47 
4 0.88 
North-west, 
4 7.79 
— 2.43 
— 10.32 
— 1.66 
The intensity of the larboard section, for example, will be 
found to have increased 1.26 from the upper to the lower 
deck, when her head was north ; to have undergone a dimi- 
nution amounting to 12.64 when it became east: and after- 
wards to have increased 7. 79 when the bow bore north-west. 
In the middle section likewise, a minute decrease of 0.89 was 
perceptible from the upper to the lower deck in her first 
situation ; a rather greater increase of 1.79 when her head 
was east ; and a diminution of 2.43 when it became north- 
west. So also in the starboard section, the magnetic influ- 
ence was found to decrease from the upper to the lower deck, 
when her head was north, by the small quantity 2.68 ; and on 
the contrary, to undergo a rapid increase of 13.47 when it 
became east ; and lastly, a considerable diminution, amount- 
ing to 10.32, when her head bore north-west. If the means 
of the intensities of the three sections be compared, with rela- 
tion to the two decks, it will be found that the magnetic 
influence suffered a small decrement of 0.76 from the upper 
to the lower deck, when the vessel's head was north ; but 
received an increment of 0.88, when her head became east ; 
