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On working steam expansively in marine engines
250
.Mechanics, Physics, and Chemistry.
the conversion of iron into steel, it will give .a greater. .p°wer of govern. ante to the operators, inasmuch as the apphcatmn ot the battery for a certain time will ensure a certain amount of carbon being taken up, absorbed, or concentrated and amalgamated with the iron; and thus, by increasing or diminishing the action of the battery, different qualities of steel will be produced, with a certainty, regularity, and efficiency which, hitherto, under the ordinary process of manufacture, has been the object wanting--the great desideratum sought after, as well as the end desired to be attained. The experiments were conducted at Sheffiehl, under the superintendence of Mr. Hunt, and in conjunction and conference with Messrs. Atkinson, of that place. If, on a more extended scale, the elec. tric process should be found practicable, we may yet have cast iron mortars, guns, and ordnance, at once carbonized into steel, and lowered in rigidity, toughness, and ductility, as well as in tensile properties, to any degree or amount of temper.
On WorMng Steam Expa~sively in .Marine Engines. By Mr. E. ALLEN.* (Continued from page 202,)
It is proposed now to consider the effect of increasing the size of the engines for expansive working, as regards the total weights carried ; and the following 'Fable XV. gives the relative increase of weight resuhing from an ordinary engine being increased in size from 1 to 1½, 2,.2~-, ~nd 3 times ; also the proportionate quantity of coal consumed ia a given time ; the saving in weight of coal balancing the increase in weight of engines, where the proportion of coal is large. The two last columns give the ratios of time, and the proportionate number of days the coal would last in the respective cases, if the gross weights carried were kept the same. The general resa|ts may be given as follows; that when the size of the engines is doubled, the gross weights of machinery and coal togelher are
and are
][uerea~e. Increased in Class I, from t.25 to 1'68 equal to 34 per cent. " in Class 2, from 2"00 to 2"21 equal to I 0 ] " " in Class 3, fl'om 2.50 to 2"56 equal to 2~ " Decrease. Decreased in Class 4, from 5"00 to 4"34 equal to 13 per cent. '+ in Class 5, fl'om S'00 to 6"47 equal to 19 "
A|so, when the size of the engines is increased to 3 times, the gross weightg of machinery and coal together are
and are
Increase. Increased in Class I, from 1.25 to .°.I4 equal to 71 per cent. " in Class 2, from 2"00 to '2'57 equal to 28~ " " in Class 3, from 2"50 to 2'85 equal to 14 " Decrease. Dee,cased in Class 4, from 5"00 to 4'28 equal to 14 per cent. " in Class 5, from 8"00 to 5.99 equal to 25 " " From the Load. Mechanics' Mag., Aug., 1855.
On Worki~g Sleam Expansively in J~larlneEngines.
251
TABL~ XV. Table showing the Proporlionate Weights of Machinery and Coal, and Joint Weights of same, when the size m" ~Torninal Horse-Power of Engines is varied (Indicated ttorse-p6wer supposed the same iu all eases' respectively), B.atios of Nomiual IIorse~ power
1
1
.?
River.
2} 3
I : Ratms of lllatlns of V,eight i ] Rat os of Wright of Ma- of Coal corres- ] ~Time the Coal ¢hinery ........ s- I pondillg to tR~tiosoI] woutdlast if l{g ponding to Iu- t Incr~ase~of 1 Total ] the~!gotal h cre~'~c of Nomi- Nominal Ilorse- Weights I Wts. be kupt Da: nat lIors(~-power, power. I | the same° 1"00
1"25 t'50 1"75 2"00
~
"25 "20 "t8 "16 "14
1'25 1"45 1"68 1"9t 2"14
1
• •
i. . . . .
2
Coasting a n d Uontine~ltM.
i
1.oo
10o
2 2,~
1"25 1"50 1"75
"8 l "71 "63
3
2"00
"57
. . . .
3
4
Ocean ( L o n g Voyages.) A u s tralian.
'92 "70 "39
7 4
2"57_ t
"00
0
[ 2,50 t 2.46 2,56 2.69 __2'85
1.00 1"03 .94 "80 .59
15 15~ 14 12
I I I I ]
5.00 4-49 4"34 4.27 4.28
1,00 1.15 1.~3 1.29 1,31
4O 46 49 51
8"00 6-92 6.47 6"16 5'99
1'00 1"19 1"30 1'41 1"50
l
1½ 2 ~,~ 3
1.00 1.25 1-50 1.75 2-00
1.50 1.21 1.06 .94: __'85__
1 1~ 2 2~ 3
t.00 1-25 1.50 1.75 ~.00
4.00 3"~24 2+8+ 2,52 2.28
1
Ocean (Short Voyages) ~nd Government.
-Woo 2'06 2"21 I 2"38 I
/
!Ocean (Voyages out and h o m e , ) 5 Eastern Steam N avigationC ompany.
1
1 "00
1"°5 1'50 1"75 2"00
7-09 5-67 4-97 4,4I 3'99
9
52
17o 83 91 ' 99 [05
* T h e boilers, water, wheels, or screw are supposed the same, and the engines ~one e~lual to half the gross weight of machinery.
The last columns show that in the 4th Class, where the weight of coal carried is equal to four times the gross weight of machinery, if the size vf the engines be doubled, the same gross weight being.taken, then the ~oals will last nine days longer--equal to 22 per cent. increase ; and if the size of the engines be increased to three times, and the gross weight carried be kept tim same~ then the coal will last 1"2~ days longer--equal to 31 per cent. increase. Also, in lhe 5th Class, where the weight of coal carried is equai to seven times the gross weight of machinery, if the size of the engines be doubled, the gross weight being kept the same, then the coal will last 21 days longer--equal to 30 per cent. increase ; and if the size of the engines be increased to three times, and the gross weight carried he kept ~he same~ then the coal ~ill last 35 days longer~equal to 50 per cent. increase. The last part of the subject to be now considered is~ the effect which
Jffechanics, Physics, and Chemistry. the increase in tile size of the engines has upon t!,e total spaces occupied 252
by machinery and coals togeflwr. Table XVI. gtves the results, where the size increases from one to one and a half, two, two and a half, and three times, for the three divi,ions into which the live classes of vessels, befbre st}ekes ot, are reduced. In Class 1 the coals occupy a space equal to that occupied by the engines alone ; in Classes '2 and 3, three tunes; anti in Classes 4 and 5,five times lhe space occupied by the engines ahme. The space above spoken of is horizontal spae% taken at the greatest beam of the vessels. The general results are, that if the size of the engines be doubled, then the total space occupied by machinery and coals taken together (the coals lasting the same time in all cases), In Class 1, irtcreases from 4'00 to 4'21, equal 1o .5 per cent. In (;liisses 2 and 3, decreases from G'O0 to 5,63, C,lual to O 't in C'lassrs 4 and 5, decrcasr~ from S'llO to 7'05, equal to 12 "
Also, if the size of the engines be increased three times, then the total space occupied by machinery and coals taken together~ In Class 1, increases from 4"00 to 4'57, equal to t4 per cent, In 131asses 2 and 3, d{'crrases from G'(}Oto 5"71, equal to 5 " h t Classes 4 and 5, decreases from 8'00 to 6'85, equal to 15 " 'l',m,r: XVI. Table showing the Relative ,~pnces occupied by Englnes, Boilers, and Passages, and Coals, separately and to[4elher; the size (f l~?.ninal Horse-Power increa~'ing from 1 to 3 ; t]~e Aclu'~l or Indicated Horse-Power remaining the same.
Cla~s. ]
Service.
i } Ratios of Spaces occuRatios o f Spaces pied by S •zc or " ' ,~. . , ]occu0tcd bv¢ Boilers and £~ O l l l l l l a l , " . 'ry 1~] l l g 1 l i e s Passages llorsealollP. (Constant,).~. ]lower. r
River.
2
Coasting and Con. ant~ :tinental ant Ocean 3 i ( S h o r t Voyages.) IOeean (Long Vo'¢/ages) and Easterl, 1 S t e a m Navigation m;d Companv'sVesseJs.[
i,~
1 '
1-25
:~. 3"
1.75 2"00
l 2J,
3" 1 2 2~ 8"
I i j Ratios of JRatios f t S p a c e s occu-I of [ pied by Coals,', Total f ~ ~ ! - i S p a c e s " l:
I'80 1"50
1'00 1'25 1"50 1'75 2'00 1'00 1"25
1"00 •81 '71 •63 •57
-! i -]"
8'00 2"43 2'18 1'89 1.71
5'00 -4'05 8'55 .'t'15 2'$5
4'00 4'06 4'2 [ I 4'38 t 4"57 5'68 t 5"63 [
5.64 I 5"71
s.-77;-0 I 7'30 ! 7'05 ] 6'90 2'00 6'85 f T h e actual horizontM space occupied by engines may be taken generally at ~ square foot per nominal horse-power, ~-The actual space occupied by boilers may be taken at 1 square foo~ per nominal horse.power, and passages at ~ square foot. ~ T h e space occupied by d~e coals varics,~-Clas.~ 1, ;~ squsre foot; CIasses 2 and 3, 2~: square feet ; and Cla.~se.~ 4 and 5, 8'~ square feet per nominal horse-power. l l a t i o s - - E n g l n e s , 1 ; Boilers and Passages, 2 ; Coals 1, 3, and 5 rcspcctivelyo 4
1"50 1-75
On IVorkin~ Siesta Expansively in ~Iarine Engine*.
~53
Table XVI[. shows how the cary,o space is diminished or increased under the three suppositions, that the machinery and coal space is equal to fl~c cargo space, or to hoo-thir&, or to ane-ha~the cargo space ; these prol)ortions embracing *l~e ordinary limits. TAI:L'i:: X V I I .
Table show/nu" t/~e Per ('enlq.~'e ~f Loss or (lain in Cargo ,~pece, a n d the Per Oente g e q f ,b'ezv/.;. in @*¢mLi// qf (.'oaLs' required, when tire size or 2Vomfnal tlorse}mu:cr oj" the I'LG.i~'s i:~ }ncrcc;sed, l/~e lndicaled Horse-yower beln,g, the same. f(atio~. (,f Tot::~ , TIle s:tlm~ Si?,~e:!~ o
(!(~l/tl( ~l' (ll
l~oi tl:g
Deer( a~:e.
~?ab],'.) i
1', r Ce;~ta~(,s in ~ lfi('h trio ('!/r;ro fl,aCe iS ])llnini>hcd or |l,cl'~'a>l:d. ]~t. I 2,1. 1,Vll(,it i h e bd~,l } x,Vhpn th,, t , , i al ,\!;urhhlt'Py ~HId )lltcl;illPl'y at~d C,~:tl ,<~:u':~ i,; I Ct,al Spare is (;,,',! l'~ l h c i . ! a ] !~!~ of t h , t(*tal I 'aP:~tl ?}l)a(?::. } (]al'go Splttx~.
])hni~)ishes } D i m i n i s h e s P e r (Jent. Per Gcnt.
3d. W h e n t h e total 31achillvry arid Colt| Space is Z:; of l h o total "(~argo Space. I__
Diminishes Per Cent.
4'00
1O0
4"06 4"21 4-38 4"57
10l}
6"00
l 0O
I llcreases
increases
Increases
5"68 5.63 5"64 5-71
9I 94 94 95
Per Gent. 6 6 6 5
Per Cent. 4 4 4 a}
Per Gent. 3 3 3
8'00
I00
Ir.qcr(~aScS Per Cent. 9 12
In creases Per Cent. 6 8
15
10
7"30 7"05 6.90 6'85
105 109 114
9l 8,q 86 85
1 Ilatie.g of P e r cent- I C~xd~ cm]age of Coltl s u m c d in t h e saw.'d b y sP, ille tillle~ E x p a n s i v e lind d e v e lo p Working. ie.g t h e Salile P o w e r .
100
Per C e n t ,
5
3~
e~
7t
9
6
4i 7
63 57
19 29 37 43
100
P e r Cent.
14
1~
.q~
]~I1Cl'(*ases
•
81 71 6:1 57
,
19 29 37 43
100
Per Cent,
81 71 63 57
19 29 37 43
P e r Gent.
'ak
6 7
I f the engines be doubled in size, then I'n C l a s s 1, the c a r g o s p a c e diminishes 5, 3}, and 2,~ per c e n t . In Classes 2 and 3, " ,, increases 6, 4, a n d 3 " I n Classes 4 a n d 5, " ', increases 12, 8, a n d 6 "
I f the engines be increased in size three times, then In C l a s s 1, the c a r g o space d i m i n i s h e s 14, 9½, a n d 7 per c e n t . I n Classes 2 a n d 3, " ,' increases 5, 3~, a n d ~2~ ,, I a Classes 4 a n d 5, " " i n c r e a s e s 15, 10, a n d 7~ "
T h e last column gives the per centage of saving in coal. T h e effects of increasing lhe size or nominal horse-power of engines, for the purpose of working the steam more expansively, have now bees considered~ in respect both to the increasedfirst cost ofma&inery~ so far at least as the interest on the increased capital is concerned, the saving ojfcoal in per centage of capital, the i~wrease of weigltt of machinery and the saving in weight of coal, and also in respect to the total spaces occu,",,roi,. X X X I . - - T t l I a D
S ~ I t I ] s . - - N o . 4 . ~ A P a m , 1856.
22
254 .~Iecl~a~cs, Phydcs, and Chemistry. pied by ~nachinery and coal, and also the effect of the changes on the cargo space in per centage of the first supposed cargo space ; and it is co,> sidered that the results are such as are not generally known, arid that merchants and ship-owners are wholly unaware of the advantages of working steam expansively, even should they be compelled at tl~e outset to pay double the amount now usually paid for engine power. It would appear certain that if no alternative existed but that of increasing, say the diameter of the cylinders of marine engines, and thus increasing the first cost in about the proportion of 1} limes tbr double the siz% and 2 times tbr 3 times the siz% (the boilers, wheels, or screw being supposed to remain tile same,) ample reason still exists for making such a ehar)ge in contracting for engines intended for vessels carrying a large proportion of coal ; aml it has been shown that it" double the ordinary atrlount be paid tbl' the machinery, yet 9~- per cent. increase may be paid upon the eapitat in some cases, after deducting for the extr~ cost of engines, by the economy in coal alone. It has also been shown that notwithstanding the increased size of engines (supposed to be increased three times,) the Australian vessels earrying a large prnportion of coal, present opporttmities of gaining 15 per cent. in many cases in cargo room, and further, that about 14 per cent. may be saved in the gross weights carried, taking machinery and coals together; or that so much more additional coaf could be taken tbr a longer voyage whhout re-coaling. . In the foregoing Tables, the size or nominal horse-power of engines has been supposed to be increased three times, as a limit, but no advantage has been named as resulting frmn the diminished cost of the boilers, since, less steam being required to develop the same power, smaller boilers wouhl suitice. Considerable advantage, however, would follow tl'om this reduction; or advantages might be shown, in decrease of weight and space in the boilers; but it has been considered best not to encumber the caleulmions with so many considerations. The gain in cargo space is altogether an additional saving to that already named as resulting ti'om economy in quantity of coal, but this source of profit has only been shown in a per eentage of increase of cargo space) and no money value can be set upon it, as it varies so much with the nature of the trade and freight obtained. The tbllowing Table, XVIII., presents a general summary of what has been before stated, and it will be seen from this Table, that until the uantity of coals taken in proportion to weight of machiner at least qeqrials 1~~. times, as in . Class 3, or rather unti~'it e q uals two Ymes the _gr°ss. wmght, of machinery,, no change_ could, be advanta,~eousl~,y made by increasing the normnal horse-power or raze of the engines; inasmuch as (on the conditions assumed) the weight of the machinery increases mort rapidly than the weight of the coal diminishes. In Classes 4 and 5, however, aa increase in ll~e weigltt of tlze e,)gine, is soon covered by the reduction in weight of coal required,
On Working Sleam Expansively in J~1arine Engines.
255
SU~i~Aay.
T.~nLE X V I I I . - - G E x E a ~ n
Table compiled from lhe fore~oln,¢ Tables,/he size or Nomi~al Horse,power ~q~cma~ iu,~ from 1 lo 2 and 3 times (lhe intermediale sizes being omit,ted,) and based ca lhe supposilion lhat in order to work exyansivel3/ the )~ngines must .be increased in Cost, WciL~hl, a77d Size, lhe Boilers being assumed to remain the same. The Slcum l'ressure su])posed al only about 20 lbs. above ghe.almosphere. -
!
'
i
I i S rv(e i .i ~: !-'~, i~i ', I
.................. ]
1~3Ec of Size.! ,)r No-! rains! l{ors," 1;owcr
93vln~
i:l ('~):~l i~t ],or '~,rJta~ of~:alfitai.
; I
~ Cargo Space, Decrease o r
Total {
)or Con
{ :
Cargo
. Space. . . .Space. . .{
(~argo Space.
PerCe a t N(). (~
~ge.of [n
~rease of l'imo lie Coal wou'~l last, if LheTcLa'. Weigl:ts
Coal~ will last, i{ Total WL% bekep
be k e ) t
the
~h~_.ja_, so sa~e,
Per Cent Per Cent Per Cent Per Cent.[Per Cgnt, Per Ce a t Da~s.
1
2
4.,~5
...
lncrease~ [~crease.¢ Decrease: DeereaseslDecre~ses
. ..
...
9.'A
f
1
...
Tnereaset Decrease: Inerease~ [nerea'ses{Inerea~es
..,
10
i ,.,{"°:~l n, . ~(i ~,~
~.~.~
2.15
i Oc.an ({ 3 (S o'~ -~
... 1-45
I iVovagc) (
:~'~5
! coon {41 (Lon,, { ~. o',age) 1] 5i (Voyage ()~c~m O u t tn~ I i Itome)
Cargo
. . . . . When { When rotal ~l'm/Totnl 5In chinery t ehinery and Coal /and Coal S~aee~is ] S p a c e i s ~of { ~/~of
(
11 ~,~-er 9, ..
]ncrease per cent.
?,pac~!s oe-I. - - - - zupiedby] W h e n Ctml andiTotal MaMaehi- { cbinery n e r y - - l n - ' a n d Coal ereasem Spaeeis Decreas~ e q ~ l a l t o
pot cent. per coat
i {
' [~
Total Weighls o f Coa] and Ms:!hiner)'-. Increase or Decrease
(] "~i ( J(/] (!
... ~"25 1C'l~, ]'~-~ ~,~ x ia
04
~o~
5
5
3~ I
2½
2s~
~
5
~
5
,
3~
~
14
,~
5
3,/:,
~½
.. .. .. .. ... .
9.½
lner(,a'se~ Deercase~ [ne~'ease~ [nerea,~es Increases 2~ 6 6 4 3
... ......
15
......
Decreasc~ Decrease,, [ncrease~ increases In.creases 13 12 12 8 6 14 15 15 10 71/22 Decrease,' 19 Dcerease~' [ncrease~ increases Increases ,,= 12 12 8 6 ~o 15 15 10 7y~
. .. 22 31 ... B0 50
40 49 52~ 70 Ol 105
The increase in the weight of engines would be found to be about balanced by the decrease in weight of coal required, if the quantity o[ coal taken was equal to double the gross weight of machinery ; the boilers being supposed to remain the same. In these calcala.tions it must be remembered, that t.he boilers are supposed ;to remain the same, and the weight of the engines alone are stlpposed to increase in the ratio of 1½ times the weight tbr double the size or nominal horse-power, and two times the weight for three times the size or nominal horse-power. The iinportanee of the gain in eargo-spaee, may be thus estimated, (taking the Australian vessels as an instance) : Supposed c a p i t a l
of company, • . £ 100 W o r k i u g e x p e n s e s s u p p o s e d at 65 p. C., w i t h t h e coals 2 5 , p c., 6 5 To pay 5 per cent. the receipts must be 70 "With e n g i n e s i n c r e a s e d to t h r c e t i m e s s i z e 'File c a p i t a l i n c r e a s e d to • .. 180 M / o r k i n g e x p e n s e s r e d u c e d b y s a v i n g of 43 p e r cent., off c o a l s at 25 p e r cent., . 54 T o p a y 5 p e r c e n t . tim r e c e i p t s n e e d o n l y be ( £ 5 4 - 5 0 X
£6 loo)
0 0 0
0 0 0
0
I)
5
0
60 15
0
But the receipts on former supposition are £ 7 0 , showing an addition of 7 per cent. on the increased capital~ or 9¼ per cent. on the original supposed capital.
256
,Mechanics, Physics, and Chemistry.
To this add from 7½- to 15, say 10 per cent. on receipts, extra cargo space, equal to ~ 7 . T h i s gives t o t a l receipts, Working expenses, •
. £ 77 54
B a l a n c e for dividend,
0 5
0 0
£ 22 15
0
This on £ 1 3 0 equals 17,} per cent. It can be shaven also that with improved macldaery, comparatively no extra capital would be needed, and flint no additional space would be required in one engine room, so that a saving o f 43 per ce)~Lin coal wouhl give 10} per cent. on capital in the case of Australian vessels, and add besides, fi'om 13,} per cent. to27per eent.~say 18 per cent. to the cargo space, and consequently to the receipts~ T h u s , capital, • ~ 100 0 Vv'm'ldng e x p e n s e s reduced to 54 5 Receipts as b e f o r e , £ 7 0 , to which add 1S per cent. ~ 22 1; 12 0 lbr ext.ra c a r g o space, m a k i n g ~otal receipts, . 82 12 L e a v i n g for dividmld,
£ 28
7
0 0 0 0
( T o be c o n t i n u e d . )
For the ffournM of the F r a n k l i n Institute.
On the .Manne~" o f Stee,ri~g Sleamers; and on ,Jql/~warlship B~d/cSeads. BOARD OF UNDERWRITERS, ,~ew ]7o?'/t?, ]'(/b. 11 , 1S56.
.DearSir :--In consideration of the peril incurred, and injury sustained by the steamer Persia upon her last trip from Liverpool here, i beg leave to renew my suggestion of a previous date~ regarding the ,harmer of steering sleamers, wherein I recommended that the owners of a!l sleamers be required to have them steered forwards instead of aft, as is customary in our Mlantie Lines, and at the same time to invite your attention to the subject ,~f athwartship bulkheads. In order 1o present this subject of steering to you in ,as brief a manner as praetieal01e, I submit the fvllowing summary of tim elements of the case, and the advantages of such a change. When a steamer is steered aft, there is required in addiIion to the oNeer of the watch, a second e n t e r to be stationed aft, to eornmenicate ~rders to the helmsman, the duty of look-outs being confided alone to the forecastle watch, and to ti~e officer of the watch. When the wheel is placed fl)rward, the number of look-outs is increased by the addition of the second of~eer of the watch and the hel.,s~slnan.
When an observation forward renders necessary immediate action with the wheel, the order is given from the tbreeastle to the officer of the watch; by him it is repeated to the officer of the wheel, and by him to the ~heel; this course involving both a delay and ambiguity of interprelotion that has in many eases proved fatal. Regarding the construction and use of alhwartship bulkheads, it is unnecessary for me to enter into any details, as the subject is at this time
.Mechanics, Physics, and Chemistry.
the conversion of iron into steel, it will give .a greater. .p°wer of govern. ante to the operators, inasmuch as the apphcatmn ot the battery for a certain time will ensure a certain amount of carbon being taken up, absorbed, or concentrated and amalgamated with the iron; and thus, by increasing or diminishing the action of the battery, different qualities of steel will be produced, with a certainty, regularity, and efficiency which, hitherto, under the ordinary process of manufacture, has been the object wanting--the great desideratum sought after, as well as the end desired to be attained. The experiments were conducted at Sheffiehl, under the superintendence of Mr. Hunt, and in conjunction and conference with Messrs. Atkinson, of that place. If, on a more extended scale, the elec. tric process should be found practicable, we may yet have cast iron mortars, guns, and ordnance, at once carbonized into steel, and lowered in rigidity, toughness, and ductility, as well as in tensile properties, to any degree or amount of temper.
On WorMng Steam Expa~sively in .Marine Engines. By Mr. E. ALLEN.* (Continued from page 202,)
It is proposed now to consider the effect of increasing the size of the engines for expansive working, as regards the total weights carried ; and the following 'Fable XV. gives the relative increase of weight resuhing from an ordinary engine being increased in size from 1 to 1½, 2,.2~-, ~nd 3 times ; also the proportionate quantity of coal consumed ia a given time ; the saving in weight of coal balancing the increase in weight of engines, where the proportion of coal is large. The two last columns give the ratios of time, and the proportionate number of days the coal would last in the respective cases, if the gross weights carried were kept the same. The general resa|ts may be given as follows; that when the size of the engines is doubled, the gross weights of machinery and coal togelher are
and are
][uerea~e. Increased in Class I, from t.25 to 1'68 equal to 34 per cent. " in Class 2, from 2"00 to 2"21 equal to I 0 ] " " in Class 3, fl'om 2.50 to 2"56 equal to 2~ " Decrease. Decreased in Class 4, from 5"00 to 4"34 equal to 13 per cent. '+ in Class 5, fl'om S'00 to 6"47 equal to 19 "
A|so, when the size of the engines is increased to 3 times, the gross weightg of machinery and coal together are
and are
Increase. Increased in Class I, from 1.25 to .°.I4 equal to 71 per cent. " in Class 2, from 2"00 to '2'57 equal to 28~ " " in Class 3, from 2"50 to 2'85 equal to 14 " Decrease. Dee,cased in Class 4, from 5"00 to 4'28 equal to 14 per cent. " in Class 5, from 8"00 to 5.99 equal to 25 " " From the Load. Mechanics' Mag., Aug., 1855.
On Worki~g Sleam Expansively in J~larlneEngines.
251
TABL~ XV. Table showing the Proporlionate Weights of Machinery and Coal, and Joint Weights of same, when the size m" ~Torninal Horse-Power of Engines is varied (Indicated ttorse-p6wer supposed the same iu all eases' respectively), B.atios of Nomiual IIorse~ power
1
1
.?
River.
2} 3
I : Ratms of lllatlns of V,eight i ] Rat os of Wright of Ma- of Coal corres- ] ~Time the Coal ¢hinery ........ s- I pondillg to tR~tiosoI] woutdlast if l{g ponding to Iu- t Incr~ase~of 1 Total ] the~!gotal h cre~'~c of Nomi- Nominal Ilorse- Weights I Wts. be kupt Da: nat lIors(~-power, power. I | the same° 1"00
1"25 t'50 1"75 2"00
~
"25 "20 "t8 "16 "14
1'25 1"45 1"68 1"9t 2"14
1
• •
i. . . . .
2
Coasting a n d Uontine~ltM.
i
1.oo
10o
2 2,~
1"25 1"50 1"75
"8 l "71 "63
3
2"00
"57
. . . .
3
4
Ocean ( L o n g Voyages.) A u s tralian.
'92 "70 "39
7 4
2"57_ t
"00
0
[ 2,50 t 2.46 2,56 2.69 __2'85
1.00 1"03 .94 "80 .59
15 15~ 14 12
I I I I ]
5.00 4-49 4"34 4.27 4.28
1,00 1.15 1.~3 1.29 1,31
4O 46 49 51
8"00 6-92 6.47 6"16 5'99
1'00 1"19 1"30 1'41 1"50
l
1½ 2 ~,~ 3
1.00 1.25 1-50 1.75 2-00
1.50 1.21 1.06 .94: __'85__
1 1~ 2 2~ 3
t.00 1-25 1.50 1.75 ~.00
4.00 3"~24 2+8+ 2,52 2.28
1
Ocean (Short Voyages) ~nd Government.
-Woo 2'06 2"21 I 2"38 I
/
!Ocean (Voyages out and h o m e , ) 5 Eastern Steam N avigationC ompany.
1
1 "00
1"°5 1'50 1"75 2"00
7-09 5-67 4-97 4,4I 3'99
9
52
17o 83 91 ' 99 [05
* T h e boilers, water, wheels, or screw are supposed the same, and the engines ~one e~lual to half the gross weight of machinery.
The last columns show that in the 4th Class, where the weight of coal carried is equal to four times the gross weight of machinery, if the size vf the engines be doubled, the same gross weight being.taken, then the ~oals will last nine days longer--equal to 22 per cent. increase ; and if the size of the engines be increased to three times, and the gross weight carried be kept tim same~ then the coal will last 1"2~ days longer--equal to 31 per cent. increase. Also, in lhe 5th Class, where the weight of coal carried is equai to seven times the gross weight of machinery, if the size of the engines be doubled, the gross weight being kept the same, then the coal will last 21 days longer--equal to 30 per cent. increase ; and if the size of the engines be increased to three times, and the gross weight carried he kept ~he same~ then the coal ~ill last 35 days longer~equal to 50 per cent. increase. The last part of the subject to be now considered is~ the effect which
Jffechanics, Physics, and Chemistry. the increase in tile size of the engines has upon t!,e total spaces occupied 252
by machinery and coals togeflwr. Table XVI. gtves the results, where the size increases from one to one and a half, two, two and a half, and three times, for the three divi,ions into which the live classes of vessels, befbre st}ekes ot, are reduced. In Class 1 the coals occupy a space equal to that occupied by the engines alone ; in Classes '2 and 3, three tunes; anti in Classes 4 and 5,five times lhe space occupied by the engines ahme. The space above spoken of is horizontal spae% taken at the greatest beam of the vessels. The general results are, that if the size of the engines be doubled, then the total space occupied by machinery and coals taken together (the coals lasting the same time in all cases), In Class 1, irtcreases from 4'00 to 4'21, equal 1o .5 per cent. In (;liisses 2 and 3, decreases from G'O0 to 5,63, C,lual to O 't in C'lassrs 4 and 5, decrcasr~ from S'llO to 7'05, equal to 12 "
Also, if the size of the engines be increased three times, then the total space occupied by machinery and coals taken together~ In Class 1, increases from 4"00 to 4'57, equal to t4 per cent, In 131asses 2 and 3, d{'crrases from G'(}Oto 5"71, equal to 5 " h t Classes 4 and 5, decreases from 8'00 to 6'85, equal to 15 " 'l',m,r: XVI. Table showing the Relative ,~pnces occupied by Englnes, Boilers, and Passages, and Coals, separately and to[4elher; the size (f l~?.ninal Horse-Power increa~'ing from 1 to 3 ; t]~e Aclu'~l or Indicated Horse-Power remaining the same.
Cla~s. ]
Service.
i } Ratios of Spaces occuRatios o f Spaces pied by S •zc or " ' ,~. . , ]occu0tcd bv¢ Boilers and £~ O l l l l l l a l , " . 'ry 1~] l l g 1 l i e s Passages llorsealollP. (Constant,).~. ]lower. r
River.
2
Coasting and Con. ant~ :tinental ant Ocean 3 i ( S h o r t Voyages.) IOeean (Long Vo'¢/ages) and Easterl, 1 S t e a m Navigation m;d Companv'sVesseJs.[
i,~
1 '
1-25
:~. 3"
1.75 2"00
l 2J,
3" 1 2 2~ 8"
I i j Ratios of JRatios f t S p a c e s occu-I of [ pied by Coals,', Total f ~ ~ ! - i S p a c e s " l:
I'80 1"50
1'00 1'25 1"50 1'75 2'00 1'00 1"25
1"00 •81 '71 •63 •57
-! i -]"
8'00 2"43 2'18 1'89 1.71
5'00 -4'05 8'55 .'t'15 2'$5
4'00 4'06 4'2 [ I 4'38 t 4"57 5'68 t 5"63 [
5.64 I 5"71
s.-77;-0 I 7'30 ! 7'05 ] 6'90 2'00 6'85 f T h e actual horizontM space occupied by engines may be taken generally at ~ square foot per nominal horse-power, ~-The actual space occupied by boilers may be taken at 1 square foo~ per nominal horse.power, and passages at ~ square foot. ~ T h e space occupied by d~e coals varics,~-Clas.~ 1, ;~ squsre foot; CIasses 2 and 3, 2~: square feet ; and Cla.~se.~ 4 and 5, 8'~ square feet per nominal horse-power. l l a t i o s - - E n g l n e s , 1 ; Boilers and Passages, 2 ; Coals 1, 3, and 5 rcspcctivelyo 4
1"50 1-75
On IVorkin~ Siesta Expansively in ~Iarine Engine*.
~53
Table XVI[. shows how the cary,o space is diminished or increased under the three suppositions, that the machinery and coal space is equal to fl~c cargo space, or to hoo-thir&, or to ane-ha~the cargo space ; these prol)ortions embracing *l~e ordinary limits. TAI:L'i:: X V I I .
Table show/nu" t/~e Per ('enlq.~'e ~f Loss or (lain in Cargo ,~pece, a n d the Per Oente g e q f ,b'ezv/.;. in @*¢mLi// qf (.'oaLs' required, when tire size or 2Vomfnal tlorse}mu:cr oj" the I'LG.i~'s i:~ }ncrcc;sed, l/~e lndicaled Horse-yower beln,g, the same. f(atio~. (,f Tot::~ , TIle s:tlm~ Si?,~e:!~ o
(!(~l/tl( ~l' (ll
l~oi tl:g
Deer( a~:e.
~?ab],'.) i
1', r Ce;~ta~(,s in ~ lfi('h trio ('!/r;ro fl,aCe iS ])llnini>hcd or |l,cl'~'a>l:d. ]~t. I 2,1. 1,Vll(,it i h e bd~,l } x,Vhpn th,, t , , i al ,\!;urhhlt'Py ~HId )lltcl;illPl'y at~d C,~:tl ,<~:u':~ i,; I Ct,al Spare is (;,,',! l'~ l h c i . ! a ] !~!~ of t h , t(*tal I 'aP:~tl ?}l)a(?::. } (]al'go Splttx~.
])hni~)ishes } D i m i n i s h e s P e r (Jent. Per Gcnt.
3d. W h e n t h e total 31achillvry arid Colt| Space is Z:; of l h o total "(~argo Space. I__
Diminishes Per Cent.
4'00
1O0
4"06 4"21 4-38 4"57
10l}
6"00
l 0O
I llcreases
increases
Increases
5"68 5.63 5"64 5-71
9I 94 94 95
Per Gent. 6 6 6 5
Per Cent. 4 4 4 a}
Per Gent. 3 3 3
8'00
I00
Ir.qcr(~aScS Per Cent. 9 12
In creases Per Cent. 6 8
15
10
7"30 7"05 6.90 6'85
105 109 114
9l 8,q 86 85
1 Ilatie.g of P e r cent- I C~xd~ cm]age of Coltl s u m c d in t h e saw.'d b y sP, ille tillle~ E x p a n s i v e lind d e v e lo p Working. ie.g t h e Salile P o w e r .
100
Per C e n t ,
5
3~
e~
7t
9
6
4i 7
63 57
19 29 37 43
100
P e r Cent.
14
1~
.q~
]~I1Cl'(*ases
•
81 71 6:1 57
,
19 29 37 43
100
Per Cent,
81 71 63 57
19 29 37 43
P e r Gent.
'ak
6 7
I f the engines be doubled in size, then I'n C l a s s 1, the c a r g o s p a c e diminishes 5, 3}, and 2,~ per c e n t . In Classes 2 and 3, " ,, increases 6, 4, a n d 3 " I n Classes 4 a n d 5, " ', increases 12, 8, a n d 6 "
I f the engines be increased in size three times, then In C l a s s 1, the c a r g o space d i m i n i s h e s 14, 9½, a n d 7 per c e n t . I n Classes 2 a n d 3, " ,' increases 5, 3~, a n d ~2~ ,, I a Classes 4 a n d 5, " " i n c r e a s e s 15, 10, a n d 7~ "
T h e last column gives the per centage of saving in coal. T h e effects of increasing lhe size or nominal horse-power of engines, for the purpose of working the steam more expansively, have now bees considered~ in respect both to the increasedfirst cost ofma&inery~ so far at least as the interest on the increased capital is concerned, the saving ojfcoal in per centage of capital, the i~wrease of weigltt of machinery and the saving in weight of coal, and also in respect to the total spaces occu,",,roi,. X X X I . - - T t l I a D
S ~ I t I ] s . - - N o . 4 . ~ A P a m , 1856.
22
254 .~Iecl~a~cs, Phydcs, and Chemistry. pied by ~nachinery and coal, and also the effect of the changes on the cargo space in per centage of the first supposed cargo space ; and it is co,> sidered that the results are such as are not generally known, arid that merchants and ship-owners are wholly unaware of the advantages of working steam expansively, even should they be compelled at tl~e outset to pay double the amount now usually paid for engine power. It would appear certain that if no alternative existed but that of increasing, say the diameter of the cylinders of marine engines, and thus increasing the first cost in about the proportion of 1} limes tbr double the siz% and 2 times tbr 3 times the siz% (the boilers, wheels, or screw being supposed to remain tile same,) ample reason still exists for making such a ehar)ge in contracting for engines intended for vessels carrying a large proportion of coal ; aml it has been shown that it" double the ordinary atrlount be paid tbl' the machinery, yet 9~- per cent. increase may be paid upon the eapitat in some cases, after deducting for the extr~ cost of engines, by the economy in coal alone. It has also been shown that notwithstanding the increased size of engines (supposed to be increased three times,) the Australian vessels earrying a large prnportion of coal, present opporttmities of gaining 15 per cent. in many cases in cargo room, and further, that about 14 per cent. may be saved in the gross weights carried, taking machinery and coals together; or that so much more additional coaf could be taken tbr a longer voyage whhout re-coaling. . In the foregoing Tables, the size or nominal horse-power of engines has been supposed to be increased three times, as a limit, but no advantage has been named as resulting frmn the diminished cost of the boilers, since, less steam being required to develop the same power, smaller boilers wouhl suitice. Considerable advantage, however, would follow tl'om this reduction; or advantages might be shown, in decrease of weight and space in the boilers; but it has been considered best not to encumber the caleulmions with so many considerations. The gain in cargo space is altogether an additional saving to that already named as resulting ti'om economy in quantity of coal, but this source of profit has only been shown in a per eentage of increase of cargo space) and no money value can be set upon it, as it varies so much with the nature of the trade and freight obtained. The tbllowing Table, XVIII., presents a general summary of what has been before stated, and it will be seen from this Table, that until the uantity of coals taken in proportion to weight of machiner at least qeqrials 1~~. times, as in . Class 3, or rather unti~'it e q uals two Ymes the _gr°ss. wmght, of machinery,, no change_ could, be advanta,~eousl~,y made by increasing the normnal horse-power or raze of the engines; inasmuch as (on the conditions assumed) the weight of the machinery increases mort rapidly than the weight of the coal diminishes. In Classes 4 and 5, however, aa increase in ll~e weigltt of tlze e,)gine, is soon covered by the reduction in weight of coal required,
On Working Sleam Expansively in J~1arine Engines.
255
SU~i~Aay.
T.~nLE X V I I I . - - G E x E a ~ n
Table compiled from lhe fore~oln,¢ Tables,/he size or Nomi~al Horse,power ~q~cma~ iu,~ from 1 lo 2 and 3 times (lhe intermediale sizes being omit,ted,) and based ca lhe supposilion lhat in order to work exyansivel3/ the )~ngines must .be increased in Cost, WciL~hl, a77d Size, lhe Boilers being assumed to remain the same. The Slcum l'ressure su])posed al only about 20 lbs. above ghe.almosphere. -
!
'
i
I i S rv(e i .i ~: !-'~, i~i ', I
.................. ]
1~3Ec of Size.! ,)r No-! rains! l{ors," 1;owcr
93vln~
i:l ('~):~l i~t ],or '~,rJta~ of~:alfitai.
; I
~ Cargo Space, Decrease o r
Total {
)or Con
{ :
Cargo
. Space. . . .Space. . .{
(~argo Space.
PerCe a t N(). (~
~ge.of [n
~rease of l'imo lie Coal wou'~l last, if LheTcLa'. Weigl:ts
Coal~ will last, i{ Total WL% bekep
be k e ) t
the
~h~_.ja_, so sa~e,
Per Cent Per Cent Per Cent Per Cent.[Per Cgnt, Per Ce a t Da~s.
1
2
4.,~5
...
lncrease~ [~crease.¢ Decrease: DeereaseslDecre~ses
. ..
...
9.'A
f
1
...
Tnereaset Decrease: Inerease~ [nerea'ses{Inerea~es
..,
10
i ,.,{"°:~l n, . ~(i ~,~
~.~.~
2.15
i Oc.an ({ 3 (S o'~ -~
... 1-45
I iVovagc) (
:~'~5
! coon {41 (Lon,, { ~. o',age) 1] 5i (Voyage ()~c~m O u t tn~ I i Itome)
Cargo
. . . . . When { When rotal ~l'm/Totnl 5In chinery t ehinery and Coal /and Coal S~aee~is ] S p a c e i s ~of { ~/~of
(
11 ~,~-er 9, ..
]ncrease per cent.
?,pac~!s oe-I. - - - - zupiedby] W h e n Ctml andiTotal MaMaehi- { cbinery n e r y - - l n - ' a n d Coal ereasem Spaeeis Decreas~ e q ~ l a l t o
pot cent. per coat
i {
' [~
Total Weighls o f Coa] and Ms:!hiner)'-. Increase or Decrease
(] "~i ( J(/] (!
... ~"25 1C'l~, ]'~-~ ~,~ x ia
04
~o~
5
5
3~ I
2½
2s~
~
5
~
5
,
3~
~
14
,~
5
3,/:,
~½
.. .. .. .. ... .
9.½
lner(,a'se~ Deercase~ [ne~'ease~ [nerea,~es Increases 2~ 6 6 4 3
... ......
15
......
Decreasc~ Decrease,, [ncrease~ increases In.creases 13 12 12 8 6 14 15 15 10 71/22 Decrease,' 19 Dcerease~' [ncrease~ increases Increases ,,= 12 12 8 6 ~o 15 15 10 7y~
. .. 22 31 ... B0 50
40 49 52~ 70 Ol 105
The increase in the weight of engines would be found to be about balanced by the decrease in weight of coal required, if the quantity o[ coal taken was equal to double the gross weight of machinery ; the boilers being supposed to remain the same. In these calcala.tions it must be remembered, that t.he boilers are supposed ;to remain the same, and the weight of the engines alone are stlpposed to increase in the ratio of 1½ times the weight tbr double the size or nominal horse-power, and two times the weight for three times the size or nominal horse-power. The iinportanee of the gain in eargo-spaee, may be thus estimated, (taking the Australian vessels as an instance) : Supposed c a p i t a l
of company, • . £ 100 W o r k i u g e x p e n s e s s u p p o s e d at 65 p. C., w i t h t h e coals 2 5 , p c., 6 5 To pay 5 per cent. the receipts must be 70 "With e n g i n e s i n c r e a s e d to t h r c e t i m e s s i z e 'File c a p i t a l i n c r e a s e d to • .. 180 M / o r k i n g e x p e n s e s r e d u c e d b y s a v i n g of 43 p e r cent., off c o a l s at 25 p e r cent., . 54 T o p a y 5 p e r c e n t . tim r e c e i p t s n e e d o n l y be ( £ 5 4 - 5 0 X
£6 loo)
0 0 0
0 0 0
0
I)
5
0
60 15
0
But the receipts on former supposition are £ 7 0 , showing an addition of 7 per cent. on the increased capital~ or 9¼ per cent. on the original supposed capital.
256
,Mechanics, Physics, and Chemistry.
To this add from 7½- to 15, say 10 per cent. on receipts, extra cargo space, equal to ~ 7 . T h i s gives t o t a l receipts, Working expenses, •
. £ 77 54
B a l a n c e for dividend,
0 5
0 0
£ 22 15
0
This on £ 1 3 0 equals 17,} per cent. It can be shaven also that with improved macldaery, comparatively no extra capital would be needed, and flint no additional space would be required in one engine room, so that a saving o f 43 per ce)~Lin coal wouhl give 10} per cent. on capital in the case of Australian vessels, and add besides, fi'om 13,} per cent. to27per eent.~say 18 per cent. to the cargo space, and consequently to the receipts~ T h u s , capital, • ~ 100 0 Vv'm'ldng e x p e n s e s reduced to 54 5 Receipts as b e f o r e , £ 7 0 , to which add 1S per cent. ~ 22 1; 12 0 lbr ext.ra c a r g o space, m a k i n g ~otal receipts, . 82 12 L e a v i n g for dividmld,
£ 28
7
0 0 0 0
( T o be c o n t i n u e d . )
For the ffournM of the F r a n k l i n Institute.
On the .Manne~" o f Stee,ri~g Sleamers; and on ,Jql/~warlship B~d/cSeads. BOARD OF UNDERWRITERS, ,~ew ]7o?'/t?, ]'(/b. 11 , 1S56.
.DearSir :--In consideration of the peril incurred, and injury sustained by the steamer Persia upon her last trip from Liverpool here, i beg leave to renew my suggestion of a previous date~ regarding the ,harmer of steering sleamers, wherein I recommended that the owners of a!l sleamers be required to have them steered forwards instead of aft, as is customary in our Mlantie Lines, and at the same time to invite your attention to the subject ,~f athwartship bulkheads. In order 1o present this subject of steering to you in ,as brief a manner as praetieal01e, I submit the fvllowing summary of tim elements of the case, and the advantages of such a change. When a steamer is steered aft, there is required in addiIion to the oNeer of the watch, a second e n t e r to be stationed aft, to eornmenicate ~rders to the helmsman, the duty of look-outs being confided alone to the forecastle watch, and to ti~e officer of the watch. When the wheel is placed fl)rward, the number of look-outs is increased by the addition of the second of~eer of the watch and the hel.,s~slnan.
When an observation forward renders necessary immediate action with the wheel, the order is given from the tbreeastle to the officer of the watch; by him it is repeated to the officer of the wheel, and by him to the ~heel; this course involving both a delay and ambiguity of interprelotion that has in many eases proved fatal. Regarding the construction and use of alhwartship bulkheads, it is unnecessary for me to enter into any details, as the subject is at this time