distribution, &c. of the magnetic intensity in ships of war. 329 
This anomaly is no doubt to be attributed to the partial em- 
ployment of iron in the inner circumference. 
The mean of all the intensities of the stations in the lesser 
circumference was 102.03, and of the greater 104.40. The 
starboard semi-circle also of the former gave a mean inten- 
sity of 101.37, and the larboard 101.69; — approaching 
nearly to equality with each other. The mean intensity of 
the starboard semi-circle of the exterior circumference, was 
105.46, and of the larboard 102.09. This excess of the in- 
tensity of the former semicircle above the latter, accords 
with the conclusions before deduced, relatively to the sec- 
tions of the same name. 
On removing the binnacle, and determining the intensity 
at the centre of the concentric circles, on the horizontal roof 
of the sky light on which the binnacle rested, the intensity 
was found to be 100.29, differing but little from the assumed 
terrestrial intensity ; and hence it may be inferred, by com- 
paring the last mentioned result, with the mean intensities of 
the stations in the two circumferences, that the intensity in- 
creases nearly in proportion to the radius, in a circular space 
surrounding the binnacle, and of which © is the centre. 
At twelve inches above the surface of the compass card, 
the intensity at A was found to be 96.01, and at A '93.59, 
At © also, immediately over the centre of the concentric cir- 
cles, and at an elevation three inches greater than that last 
alluded to, it was 96.85. The difference between the inten- 
sities at A, A' arose from the compasses ; that on the star- 
board side being heavy, and employed in cases when the 
ship is much disturbed by the sea; and that on the larboard, 
mdcccxxiv U u 
