TRANSACTIONS OF THE SECTIONS. 
55 
On the Inefficient of the Aids of Science at present in connexion with tlie 
Compaws of Iron Ships . By J. T. Towson, Secretary to the Local 
Marine Board, Liverpool. , , 
In the name of the merchants and shipowners of Liverpool, he implored the 
attention of the Section to this important subject, in the hope and belief that the 
mfinbers should respond to that appeal, they would be able, before the next Meet- 
iic, to confer the benefit they smlgnt, not on their account alone, noi in consi er - 
t of the vast amount of property involved, but for the sake of the vast amount ot 
Idfiixn life which was continually being jeopardized aud lost. They- matte 
tvqaest in the belief that the compasses of iron vesse ls, if aided by all the appliances 
vhirh science at present afforded, and adjusted and managed by the most talented 
!’"!!viduals whom owners could engage, were still unworthy of confidence. 
Dr. Scoreshy had correctly arranged magnets in three classes, permanent, re- 
tmtiVe, aud inductive. The term “ retentive" ought, in his opiniou, to receive tne 
‘ Action of the Section. The Rev. Doctor had relieved him from a great amount ot 
wfficulty in expressing his opinions on ihe subject. He did not dissent from any- 
V* "*at he had said ; but he wished to point out what he believed to be another 
viircc nf error in connexion with compasses, deserving their serious consideration. 
He alluded to the change that took place in the inductive magnetism of a ship when 
7 over. In 1846, Mr. Walker, the Queen's Harbour-master at Plymouth, 
";’^ned the permission of the Admiralty to examine the compasses of the ‘Recruit 
■ D llE,p lingi and the result was. that the error from this canse was found to 
wiuunt tu nearly one-half the maximum error experienced when on an even beam. 
, ‘ be ' lev . ct * tbat many of the errors in compasses on board both wood and iron 
’r». which neither the mariner nor the compass-adjuster could account ,or > waa 
•;7 altnbnted to '* heeling." iu the only six cases in which he had been able to 
information of the heeling of iron slims, it had been shown that considerable 
li 0 / 3 nr > st n from this cause ; bat these, of course, were not sufficient to esta- 
g.i.v} '**>'?• He thought, however, that the disastrous loss of the ' layleur 
of *J 1 "’i 8,hl y ha ve arisen from this cause, All t.hc tables of deviation*of compasses 
whu, iL u h . R( ! lieeled bad the maximum amount of error, arising from heeling, 
Iht ism. l • P 8 head waa directed within two or three points of the magnetic pole , 
1 1 caw* t,le l >0 ‘ nt ol ' no-deviation when the ship’s beam was horizonta . 
*.h t JS'tS? ® 0rt J pole of the compass had been drawn towards tJic point to which 
“-it L heelcd ' Hesides collateral means adopted for correcting the compass, the 
kMn 6,„uT t r. Sln 1130 for that purpose : Cant. Johnson's system of swinging the 
•ml the d \? U allne the re8 ults, which was exclusively employed in the Ho >’ al 
wEV mer R °y al ' 8 method of compensating the compasses by means ot 
C«pt. J 0 L “ c , 1 w ? 8 alrnost exclusively resorted to in this port, i he obj 
*»y. Hill S J ,lan was > that the corrections were liable to be employed the wrong 
bad co"vin2T nce in the examination of about 2000 masters of merchant vessels 
Meucviu b . im of tbe soundness of that objection. There was ft 8 
tlia ^T l 00 t0 corae t0 a wr 0f»B concloaiou on the subject. Ihe manner 
1,1 ! Aviations indicated that the north end of the needle was drawn 
1 : "i, it m’. a<1 carne to the conclusion, that if lii.s compass had a westerly ' 
rr8J h ar,i iear P l a '^ 8e 1 Hu object bearing mirth to appear westerly, whereas 1 ‘ . 
lb? Huyal Navi’4' an ‘ 1 he hatl known the same mistake made onboard *bips in 
***. that th e •' niost. formidable objection to the Astronomer Roya y 
var )’ in I» et,C P° Ie » of the compensating magnets were liable to change o 
*'• H-established?’Theoretically, this appeared probable; but h 
bediL „ fact , to ’Unstrate it. The change of retentive magnetism, deviation 
***#» commoi , d J he . chau s e produced by going to the other hemisphere, were 
?*!* 5£il° t b ° th ^tems: Th B gr J t it evil, which in his opinion was.con- 
^nation. co,n P«Jaation, was that it concealed the amount, of orig 
v'^of hUr never ract witl > a captain who could tell him the origin 
;?«»•> of herlr pa8s if tllU3 corrected. In the case of the "layleur, the de 
.l M ’bero everl, ’’l 08 Cotn P a8a was 60°, of her compass before the jnuentnas - 
5? ; Jackal > n 9 T a , - R Caae in the Royal Navy ? Lieut. Pasco, when aPP. om . te * 
S i,0n ° f theAd 84 °.' WBS ^satisfied with a deviation of *25°, and' 
Dma“° d °ubt tV,?‘ ra ty to have the compass replaced, when it was reduced to 18 , 
if they kn mas * ers of merchant vessels on this point would be q y 
ew "what the real amount of original error was. 
