REPORT— 1854. 
162 
Dr. Scoresby said, the results of these principles establish the propositions for 
•which he has long contended, that the magnetism of all iron ships is changeable; 
and that the iron ships in which the least changes may be expected to occur are those 
which have been long in use ordinarily pursuing the same course, and those not 
making voyages further south than the Mediterranean. In such circumstances, an 
intelligent captain, by observing the changes that take place, may generall) 
confidence in his compasses. The suggestions which Dr. Scoresby made lor mo¬ 
nishing the danger arising from deviations are,—that a standard azimuth compass 
be placed on a pedestal on deck where a position of smallest deviation may be oun i 
that a compass be placed at the masthead for reference to correct errors; an 1 
care be taken on the selection of compasses to have ample directive force in <■ 
needle. _ 
On Steam-boiler Explosions. By John Sewell, Assoc. C.E. 
On the Origin of Wire Hope ; its Qualities and (Economy • 
By Andrew Smith, London. 
In the year 1848, the British Navy had in commission only 3/fl ships of 
clas9 ; at the present time there ore in commission more than double that ‘ 
The expense fpr hempen rope standing rigging for the above number <Hjmipa t c 
rope being at the rate of about £40 per ton) amounted to about .1114,‘ • . 
that time patent wire rope was .£'60 per ton; but in consequence ol wire ro P L )(ii . 
more than twice as strong for the same weight of hempen rope, the cos ^ 
standing rigging of the above number of ships, made of wire rope, 
about £80,000, thus showing a saving of about £'28,000 for one outfit ot c ^ 
Navy at that time ; but now hempen rope is about £'60 per ton, instead ot, , 
then, in 1848, £40 per ton. The Royal Navy is now supplied with wiie ro P® <■ 
rate of £'40 per ton. Now, as that supply is more than doubled in C( ’ n ^‘ 11 * 
the great increase of the Royal Navy, and as hempen rope is now about £» F b | e 
the same number of shifts would cost £228,060; and as there ia more tlinii 
the number of ships in commission at this time, ami us the price of hemp® j • 
has doubled also, and if there had been no wire rope, the Royal Navy „ 
cost the country for one outfit of standing rigging £914,640 now i ‘ 3< 
that as wire rope is only £40 per ton, instead of £60, us it was in the7“ 1(iillh - 
the saving now effected by the invention of wire rope, as applied t0 taU .. ioU > 
rigging of the Royal Navy, is about £457,320 for one outfit, without tax b 
account that it is much mure lasting or durable. Speaking from tbe “ ore 
experience, which is nearly twenty years, it may be taken us three tiro ^ 
durable ; in fact, unlike hemp, the 'older the wire is the stronger it !??“■*- rpp<( 
•hipa in the Royal Navy Lave, been fitted from fifteen to sixteen yeaisvvitft w- ^ 
and it is now as good as when first put over the masthead. Hempen rop ^ 
Royal Navy is fitted every three years, or every time that the ships are P , w j{j, 
mission ; iu the port of Liverpool a great number uf vessels have been . morC 
tins rope about fifteen years ; consequently if it is admitted to be three urn ^ 
lasting or durable than hempen rope, there would be a saving effected m . l0 
missione. or nine years, fur the standing rigging of the Royal Navy, amo ^ ^ 
the sum of £1,371,960. The uicrcliant service is using quite a* uiuc n ra j|\vay*' 
important manufacture as the Royal Navy; and its application for mines, 
submarine-telegraph cables, &c., is very great. There are at this time a ° e 
different establishments for producing this important and now staple manm ^ fiv> 
Great Britain ; and if the average produce at each establishment be ^50 
tons per day, they make 100 tons per day. If the average price be taxe 
per ton, this will amount to upwards of £1,500,000 sterling per annum- 
wire rope is now very extensively used for lightning conductors, and was nrs 
duced for the purpose by the author of this paper. 
