130 Transactions. 
acknowledging. In this vessel the co-efficients are very small, A= —1° 17’, 
B= -—0° 31’, C= +3° 31, D= + 6° 50’, E= +0° 25’, and, assuming that 
any change is due only to the influence of hard iron, I find that the greatest 
difference in deviation due to change of magnetic latitude between Auckland 
and the Bluff amounts to only 2° 32’, or a fourth of a point nearly ; this 
occurs on the N.W. point, and in a run of five miles would place the vessel 
about one-fifth of a mile to westward of its true position. It must, 
however, be thoroughly understood that no soft iron should be so placed as to 
influence the compass of the steel vessel. The changes due to difference of 
magnetic latitude, and also to heeling error, have brought a great feeling of 
distrust as to the compensation of compass errors by magnets into the 
merchant navy. This arises partly from no warning as to the existence of 
such changes being certain to take place having been given to shipmasters, 
and partly from their not having been cautioned that compensation by 
magnets is not intended to eliminate all compass errors, but only to bring 
them within such limits as may render navigation more easy. Something 
may also be dus to erroneous compensation, and thus it has happened that 
after a vessel had got some distance upon her voyage the courses steered did 
not produce the desired effect, and the magnets have been considered the 
prime cause of the ship not being in the place to which the courses steered 
should have carried het. Compasses are, in the merchant navy, frequently 
placed with the most utter indifference as to the position and amount of the 
adjacent iron, and this will be found to be the case in both wood and iron- 
built ships ; compensation in such cases is useless, as from the influence of soft 
iron the deviations are continually changing in value. It is with a view to 
the correction of this indifference that the Board of Trade now require every 
candidate for examination as Master to answer certain questions as to the 
effect of iron on the compass-needle, with the hope that the result will be in 
time that masters of vessels will attend to the placing of the compasses in 
more effective positions, and I hope that in a few years the important 
effects due to deviation, heeling error, and change of magnetic Jatitude, will be 
so well understood that it will be a matter of some difficulty to obtain 
a captain for any vessel which has not at least one compass placed with due 
regard to the magnetic character of the ship. In small vessels it is a matter 
of great difficulty to place the compasses properly, but there can be very little 
in placing them so that they may be much more reliable than is often the case 
at present. 
