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Notes on the U.S. steamer vixen
`Notes on the b)~ited States Steamer V'trx,n.
263
afforded a sufficicnt description of the invention, independently of the drawing. Some slight additions that improved the working of the ear, were open to some question~ x~'heti~e~ they were embraced in the specification, but they did not ente," into the essence of the invention, or constitute any substantial part of the improvement. Time and experience usually indicate these slight additions and alterations, and they should be regarded as consequential resuhs belonging to the inventor. It requires time and experieuce, usually, to perfect the machine, and improvements derived therefrom, are justly due to him. V..*ks to the prior use of the ear Columbus, and others constructed by the patentee bef~re he made application for his patent, we think the instruction of the court correct. The law allows the inventor a reasonable time to perfect his i,~e~,tion by experiments ; and these eoutd be made in this instance, only [)y putting the ear in the service of those controlling lines of rail roads. There were repeated failures in the experiments tried, and the ears abandoned before the perfection of the ear described in the patent. These experiments and trials sufliciently account for the previous use set up by" way of *brfeiture of the invention. Upon the whole, alter a careful examination of the case, and of all the t)oints made by the defendauts on the argument, many of which have been noticed above, we are satisfied that the verdict is right, and that a new trial should be detlied. The defendant then moved fi~r " writ of error" to the Supreme Court of the United States, on written briefs filed by D. Buel, Jr., and S. Stevens, Esqs., for the Company, and J. A. Spencer, Esq., for the plaintill which was decided January 24th, 1852, negatively. Counsel for the plaintiff then moved the Court at its late session, for an iujunction to restrain the defendants from further violating his rights, upon which motion the injunction was granted. MECHANICS, PHYSICS, AND CHEMISTRY. For the Journal of the Franklin Institute.
.~'otes on the U. S. Steamer Vixen. By Chief Engineer, B. F. IsH~mwooD, United States ,Navy. The Vixen was one of two small war steamers precisely alike, originally built for the Mcxican Government by Messrs. Brown and Bell of New York. These steamers, in an unfinished state, were, at the commencement of the late war with Mexico, still in the hands of the builders, from whom they were then purchased by the United States, armed, and employed against their original proprietors. At the termination of the war, one of them (the Spi~re) was sold, and the other ( t h e Vixen) retained ia the Navy. As first constructed, the engine of the V/xen was fitted with a piston valve and aa independent slide cut-ofi~ but on thereturn of the vessel at the conclusion of peace, double puppet valves and a cut-off, invented by Chief Engineer, Win. Sewell, U. S. Navy, were substituted; also, the depth of hold was increased from 9~ to 12 feet, and the main shaft raised one foot.
26&
21[echanlcs, Physics, and Chemistry.
"1"he results given in these notes, are fi'om the log of the vessel after the a b o v e alterations were made. T w o kinds of boilers have been used in lhe Vixen, vlz: file original b o i l e r ,with double return d,-op tlues, and tile Montgomery boiler with v e r t i c a l tubes containing the waler inside lhe tubes and having the heated g a s e s apphed externally; the space containing the heated gases being d i v i d e d vertically, ill lxv~ eom~artments. . by- a division l~late or diatfin'a,,m~, p l a c e d about midway the tubes. 'l'he results from both boilers will be g i v e n separately. ])lNt:\!;lltXq
t[L
LL. I ,cm:lh ~m dc,'k. 1~ a m , ,, I*.,pIh , d ' h
I)l" Till; YESSEL kS,I) ~IXCII1LR'EIIY, 11S feel. '22 " 6 incho~.
o
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.
.
l)raflol'~aWr,
de~'ph~:~d(Tft.gin, ])ra['i ol'x,.;Her "~ilh all c:,al otll,
.
.. fi)rward, Tlt,
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. 12 aft,')mean, 7
])lit all o l h e r w e i g h t s in, 5l(,~m draft of xx;m,r fin" t!w tim(, t,lcanie(], "Immersed alnid~hip secli m a l 7 ti?et 2 incl~es draft, . S q m m ~ feel of ilumer~,.d amid~bit~ section 1;er cubic foot o f space d i s p l a c e m e n t of pi.
I I ~ c~. ~ T w o maste(1 li,l.o a n d aft s c h o o n e r . ed unmanageable.
'<
0
"
" I0 " 6 " 6 " ~( ~t ~ 147 square feet. l~
3"467
"
I;Tnder sail alone, the vessel m a y be consider-
E ",'~; 1 x r - - - 0 n e h a l f beam horizonlaI c o n d e n s i n g engine, L i g h t h a l l ' s patent. ] ) i a m c t e r of cylinder, 3 feet. ~ t r o k e of piston . . . . 6 " ~ p a e e displacement of ldston per stroke, 4 2 ' 4 0 8 cubic feet. 12t)l 1) I'r LI: ~rI[I;3: I'.S.
D i a m e t e r from outside to outside of paddles, 18 feet 6 inches. l , e n g l h of paddle, 6 " 4 " l:lrea&h of Duldle . . . . 2 " 0 " ] ) i p of paddle at I' feet 2 iuehcs draft o f vessel, 'B " S " a \ u m h c r of paddles in each w h e e l , . . . . 1.L ~ ' u m b e r of paddh,~ in w a t c r i n c a e h wheel a t 7 feet 2 in. draft, 3. _Area of t w o paddh~s . . . . . . '~'~a~ square tbet. Mroportion of lho ;~rea of t w o padd~es to immersed a m i d s b i p seclion of lmtl, . . . . . 1"000 to 5'802 1-'roportioa of Ihe ar~".~ of nil the immersc~] paddle surlY:tee to immersed a m i d s h i p s c c l i o n o f l m l l , . 1'000 to 1'933 O ~ t ~ : ( ~ x . ~ , I l o l r . ~ : a s . - - ' l ' w o iron d o a b l e r e t u r n drop flue boilers, placed one on each s i d e t h e engine. ],e.l~glh o f e a c h boiler, 16 feet. t3rea&h '" 5 " 6inches. t{eght. " 8 " I " (.,ubw eonte~d~ of cn'cmnscrflnn~ parallelopq)edon o f each boder, 711 :~ cubic tbet. A r e a of the. he:air,g; surface iu the t w o boiler,~, 750 square tbet. grail! " 47 C a p a c i t y of steam room in boilers, . . 584 cubic feet. " " " a n d s t e a m pipe, . 615 " Cro~s area. of each of the t h r e e r o w s o f flues (both boilers), 6.303 sq. feet. C r o s s area of lhc (:hilmle3: , 6.a0a " l t e i g h t of chimney above g r a t e , . . . . 4 a feet 9 inches. M e a n pressure of s t e a m al.,o,.e a t m o s p h e r e p e r sq. in. in boilers, 12} poun&, Initial " " " cylinder, 10.3 " C u t t i n g off at, fl'om c o m m e n c e m e n t o f stroke of piston, 26~ inches, D o u b l e strokes of piston per m i n u t e , . • 14'23 C o n s u m p t i o n ot P i t t s b u r g b i t u m i n o u s coal per h o u r , with na.
•
tural draft,
"
•
•
-
"
"
•
•
°
-
1
564 I)onnds.
j'v'otes on lhe United Slates Steamer Vi.zen.
265
PROeO,tTJOXS. Proportion of h e a t i n g to g r a t e surface, , 15"958 to 1"000 ,' g r a t e zurlixcc to cr,~s area of each of the 3 ro',vs o f f l u e ~ 7..t57 " " " " chimney, 7"457 " " h e a t i n g surface to cross area o f each o f the 3 r o w s o f f l u e s , 118.991 " •' " " chimney, 118,991 " " h e a t i n g surface per cubic foot of space displacem e n t o f piston, 17.685 sq. fi, et. " grate " " " " 1'108 " " t~eafin~ ~urfaec w r cubic tbot o f space di~plae.emcnt <:t"piston, multiplied by n u m b e r o f d o u I,h. >trok,'s(11'2.3) per minute, . 1.24~ " ,' ~"r~*t ~ l r f a c o per cu] ic lbot of space di~plaeememt , f 1,ist,m, multiplied by n u m b e r ( 1 4 . 2 3 ) o f do~lbh, strokc~ per minute, • 0"078 " t'ubic fi.ot of .~t~'am ,'oom per cubic foot of steam u s e d per s coke o | ' l ~ i : i , , n . . . . 31"5~7 C o n s u m p t i o n of bituminous P i t t s b u r g coal per ~quarc tbot of g r a t e stir(ace pcr h o u r with n a t u r a l draft, . lg pounds. Con,mmption of tfitmlfinous Pitt:dmrg coal lwr square fi~ot of hv:tling surfact' per h o u r with lmtural draft, • 0.752 " Sea water evaporatett by or~e sq. [L c~f heafin~ sllrfacc per hollr, " " m;e pound of Pittsburg b i t u m i n o u s coal per h~ur, . . . . .
,
q'hese boilers, (Plate ]l,) under ordinary steaming wouhl funaish steam enough at rite above pressure to cut off"at ]aalf stroke; the piston of course making a proportionally ir:creast'd number of strokes; the coal is reported as of very i:ffL'riorquality. ]:)I.:RI"OI,:.MANCE WITH TIlE OII, IGINAI, B O I L E R S .
The following results are the mean of 311 hours steaming in the Gulf of Mexico, during the months of February and March, 1851, embracing the usual variety of wind, sea, dip of paddle, mid vessel's draft of water. The boilers were six years old, m'd very foul with incrustation. Steam pressure in boiler above atmosphere per square inch, 12~ pounds, cutting off at .06} inches from the commencement of the stroke, giving a mean effective pressure by indicator of 16 pounds per square inch of piston; number of double strokes of piston per minute, 14'23; actual horse power developed by the engine, 86'266. The speed of the vessel was 6.5:2 knots of 608"2§ feet, or 7"511 statute ,miles. The diameter of the circle of the centre of reaction was 17~ feet; the circumference normal to which is 54"19 f~et; and 5 I- 19 X 14,2 3 M fit;,: 462 ~;7.4~ l b e t = speed of centre of reaction of paddle~ per hour. 6 0 8 2 ~ X 6 ' 5 2 = 3 9 6 5 ~ ' 9 9 f i w t = s p e e d o f vessel per hour. 6f;08.43 f e e t = s l i p of centre of reaction o f paddles per h o u r . or, 14'28 per cent.
The oblique action of the paddies, calculated as the squares of the series of'their angles of incidence on the water, is 1!'94 per cent. Total losses o1" effect by the paddle wheels, (14-'28+11'94) 26"22 per cent. The evaporation was ol)tained as follows: The steam being cut off"at ~26.~inches from the commencement of the stroke, there was filled per stroke, 15"507 cubic fi~etof the cylinder, to whichmustbe added 4 cubic "VoI,. XXIII.~'.Plliax~ Smtil:s.-~No. 4 . - - A r a x ~ , 1852.
2:3
266
.Mechanics, Physics, and Chemistry.
feet comprised between the cut-off valve (which was also the steam valve,) and piston, including clearance, nozzles~ &e.~ making 19'507 cubic feet of steam of the total pressure of 25 pounds per square inch; the initial cylinder pressure being 1.7 pounds less than the boiler pressure. There would consequently be furnished per hour, (19"507X'28"46 x 60) 33349"168 cubic feet of steam of that pressure; and as the relative volumes of steam of the density due to that pressure and water are as 1044 to 1, there would be evaporated (33349"168@1044) 31"943 cubic feet of water. Taking the cubic foot of sea water at 64"3 pounds, there would be evaporated per hour, by one pound of Pittsburg bituminous ,31"943X64"3, coal, ( 5~d4...... ) 3'642 pounds of sea water; to this must be added the loss by blowi~W o.ff at -~ of Sewell's Salinometer, obtained as follows: the total heat of steam being taken at !"202 ° F., the temperature of the feed water fi'om the hot well at 100 ° F., the temperature of the steam and water in the boilers at 241 ° F., and one-half the water pumped in the boilers being bl(?wn out; the% 1~°02°--100°~1102°~ the heat used in evaporating the water; and 241°~100-=141 °, the heat used in blowing o{/, hence, 1102°-1-141°=4243 °, the total heat used and lost, and 141 is 11.34 per cent. of 1"243, leaving the complement of 100 per cent.~ or (100--11'34) 88"66 as the proportion of the total heat evolved from the fuel applied to the evaporation of the water; and as this 88"66 per cent. evaporated 3"642 pounds, 100 per cent. would evaporate 4"1.07 pounds. 'the evaporation then by one pound of Pittsburg bituminous coal per hour, would be 4"107 pounds of sea water. Increasing the total weight of water evaporated, in like manner, by the same per centage for loss by blowinN" o~, and we have the total evaporation of 36.0"29 cubic feet, or 2316'64"pounds of sea water by 750 square ibet of heating surface, being 3"089 pounds of sea water per square foot. The original boilers having become corroded out a air of the Mo tgomery ve~'tieal tubular boilers (Plate III,) were substituted in 1851. n PERFOIlh~IANCE WITH TItE MONTGOBIEt~.Y BOILERS.
The following performances of the Montgomery boilers are taken fi'om lhe Vi:ren's steam log, kept during a passage fi:om Pensacola to Key West, Florida. On this passage both Cumberland bituminous and anthracite coals were used. In both cases, the conditions of wind and sea remained sensibly the same; the wind and swell were moderate, and abeam. The boilers being nearly new, were clean and free from incrustation. The Cumberland bituminous was used for the first half of the passage, and the anthracite for the last half, with natural draft in both cases. PEIWOIRMANCE
Wl~?H TIIE CUMBERLAND.
Mean speed of vessel per hour, 6"64 knots; double strokes of piston per minute, 15"675; vacuum in condenser per gauge 26 inches of metcur),; steam pressure in boiler per square inch above atmospher% 14'67 pounds, cut of[ at 36 inches from commencement of stroke of piston; pounds of coal consumed per hour, 6"/6; sail used half the time. PERFORMANCE WITH THE ANTHRACITE.
Mean speed of vessel per hour 5'95 knots. Double strokes of piston per minute 14"88; vacuum in condenser per guage 26 in. of mercury. Steam
.]rotes on the United Slates Steamer Vixen.
267
pressure in boiler per square inch above atmosphere 14'75 pounds; cut off at 36 inches from commencement of stroke of piston. Pounds of coal consumed per hour 713. Sat[ used one-third the time. It was extremely difficult to keep steam with anthracite after the first 2-i hours; with Cumberland coal, steam was kept more easily, but after three or four days continuous steaming with it, the spaces between the tul)es would choke up, and so impair the draft as to render it necessary to stop the engines, draw the fires, cool the boiler, and clean out the tube spaces. During an attempt made to steam from Pensacola to ;New Orleans with Pittsburg bituminous coal, the tube spaces choked completely up in 24 hours, so as to wholl) destroy the draft, the flame rushing out into the fire room whenever the doors were opened, and the vessel put back to Pensacola, reaching port with difficulty. With these boilers, there is required about an hour and a quartei~ to raise steam ti'om sea water of Gulf temperature, say 60 ° F. Calculating the evaporation by the Cumberland coal in the same manr.er as befbre, there results an evaporation of 5"237 pounds of sea water l>er pound of coal per hour, and 3"248 pounds of sea water per square I5ot of healing surface per hour. Proceeding in the same manner with the anthracite, there results an evaporation of 4"713 pounds of sea water per pound of coal per hour, and 2'7~9 pounds of sea water per square foot of heating surface per hour. 3 [ o x ' r o o . ~ : u ' ; B o u . r : ~ s . T w o of iron, p l a e c d one o n each side the e n g i n e . I , e n g t h of each boiler, . 13 feet 9 inches. l~,-eadth " 5 " 6 " Ifcight ,, . . . . . 7 " 9 " C u b i c c o n t e n t s of c i r c u m s c r i b i n g p a r a l l e l o p l p e d o n of e a c h boiler, 586.09 cubic feet. A r e a of the g r a t e sm'ib.cc in the two boilers, 53.60 square feet. " heating " " 1090"00 " C apacity of s t e a m r o o m in boilers, . 890"00 cubic feet, " " " a n d s t e a m pipes, 425.00 " C ross a r e a of side flue, both boilers, . • . 7"56 s q u a r e feet. s p a c e s b e t w e e n tubes above division plate or d i a p h r a g m (both boilers), 7 . 6 4 " " " " below, " " 7"03 ~ " smoke chimney, . 8.73 " H e i g h t of snloke c h i m n e y above grate, • 4 8 feet. M e a n pressure o f s t e a m above a t m o s p h e r e per square i n c h in holler, w i t h C u m b e r l a n d coal . . . . 14-67 p o u n d s . Initial pressure of steam above a~mosphere p e r s q u a r e i n c h in cylinder w i t h C u m b e r l a n d coal, . . . 12.47 " C u t t i n g offat, f r o m c o m m e n c e m e n t o f stroke o f piston, . 3 feet. Double strokes of piston p e r minute, wltb. C u m b e r l a n d coal, 15.675 C o n s u m p t i o n of C u m h e r l a n d coal p e r h o u r w i t h n a t u r a l draft, 676 pounds. M e a n pressure o f s t e a m a b o v e a u n o s p h e r e per s q u a r e i n c h ift boiler, w i t h a n t h r a c i t e . . . . 14'75 " Initial pressure of steam above a t m o s p h e r e p e r square i n c h in cylinder, . . . . . I~.55 " C u t t i n g off at, f r o m c o m m e n c e m e n t o f stroke o f piston, 3 feet. Double strokes of piston per m i n u t e w i t h a n t h r a c i t e , 14.88 Co~asumption o f a n t h r a c i t e per h o u r with n a t u r a l draft, 718, PItOPORTIO~S,
P r o p o r t i o n of h e a t i n g to g r a t e surface, . " g r a t e surface to cross a r e a of side flue, • " " " s p a c e s , between "
tubes above diaphragm, below "
~ 0 ' 3 3 6 to 1"000 7.090 " 7.016 7"624
,,
"
263
afforded a sufficicnt description of the invention, independently of the drawing. Some slight additions that improved the working of the ear, were open to some question~ x~'heti~e~ they were embraced in the specification, but they did not ente," into the essence of the invention, or constitute any substantial part of the improvement. Time and experience usually indicate these slight additions and alterations, and they should be regarded as consequential resuhs belonging to the inventor. It requires time and experieuce, usually, to perfect the machine, and improvements derived therefrom, are justly due to him. V..*ks to the prior use of the ear Columbus, and others constructed by the patentee bef~re he made application for his patent, we think the instruction of the court correct. The law allows the inventor a reasonable time to perfect his i,~e~,tion by experiments ; and these eoutd be made in this instance, only [)y putting the ear in the service of those controlling lines of rail roads. There were repeated failures in the experiments tried, and the ears abandoned before the perfection of the ear described in the patent. These experiments and trials sufliciently account for the previous use set up by" way of *brfeiture of the invention. Upon the whole, alter a careful examination of the case, and of all the t)oints made by the defendauts on the argument, many of which have been noticed above, we are satisfied that the verdict is right, and that a new trial should be detlied. The defendant then moved fi~r " writ of error" to the Supreme Court of the United States, on written briefs filed by D. Buel, Jr., and S. Stevens, Esqs., for the Company, and J. A. Spencer, Esq., for the plaintill which was decided January 24th, 1852, negatively. Counsel for the plaintiff then moved the Court at its late session, for an iujunction to restrain the defendants from further violating his rights, upon which motion the injunction was granted. MECHANICS, PHYSICS, AND CHEMISTRY. For the Journal of the Franklin Institute.
.~'otes on the U. S. Steamer Vixen. By Chief Engineer, B. F. IsH~mwooD, United States ,Navy. The Vixen was one of two small war steamers precisely alike, originally built for the Mcxican Government by Messrs. Brown and Bell of New York. These steamers, in an unfinished state, were, at the commencement of the late war with Mexico, still in the hands of the builders, from whom they were then purchased by the United States, armed, and employed against their original proprietors. At the termination of the war, one of them (the Spi~re) was sold, and the other ( t h e Vixen) retained ia the Navy. As first constructed, the engine of the V/xen was fitted with a piston valve and aa independent slide cut-ofi~ but on thereturn of the vessel at the conclusion of peace, double puppet valves and a cut-off, invented by Chief Engineer, Win. Sewell, U. S. Navy, were substituted; also, the depth of hold was increased from 9~ to 12 feet, and the main shaft raised one foot.
26&
21[echanlcs, Physics, and Chemistry.
"1"he results given in these notes, are fi'om the log of the vessel after the a b o v e alterations were made. T w o kinds of boilers have been used in lhe Vixen, vlz: file original b o i l e r ,with double return d,-op tlues, and tile Montgomery boiler with v e r t i c a l tubes containing the waler inside lhe tubes and having the heated g a s e s apphed externally; the space containing the heated gases being d i v i d e d vertically, ill lxv~ eom~artments. . by- a division l~late or diatfin'a,,m~, p l a c e d about midway the tubes. 'l'he results from both boilers will be g i v e n separately. ])lNt:\!;lltXq
t[L
LL. I ,cm:lh ~m dc,'k. 1~ a m , ,, I*.,pIh , d ' h
I)l" Till; YESSEL kS,I) ~IXCII1LR'EIIY, 11S feel. '22 " 6 incho~.
o
h
l
.
.
l)raflol'~aWr,
de~'ph~:~d(Tft.gin, ])ra['i ol'x,.;Her "~ilh all c:,al otll,
.
.. fi)rward, Tlt,
llln,
. 12 aft,')mean, 7
])lit all o l h e r w e i g h t s in, 5l(,~m draft of xx;m,r fin" t!w tim(, t,lcanie(], "Immersed alnid~hip secli m a l 7 ti?et 2 incl~es draft, . S q m m ~ feel of ilumer~,.d amid~bit~ section 1;er cubic foot o f space d i s p l a c e m e n t of pi.
I I ~ c~. ~ T w o maste(1 li,l.o a n d aft s c h o o n e r . ed unmanageable.
'<
0
"
" I0 " 6 " 6 " ~( ~t ~ 147 square feet. l~
3"467
"
I;Tnder sail alone, the vessel m a y be consider-
E ",'~; 1 x r - - - 0 n e h a l f beam horizonlaI c o n d e n s i n g engine, L i g h t h a l l ' s patent. ] ) i a m c t e r of cylinder, 3 feet. ~ t r o k e of piston . . . . 6 " ~ p a e e displacement of ldston per stroke, 4 2 ' 4 0 8 cubic feet. 12t)l 1) I'r LI: ~rI[I;3: I'.S.
D i a m e t e r from outside to outside of paddles, 18 feet 6 inches. l , e n g l h of paddle, 6 " 4 " l:lrea&h of Duldle . . . . 2 " 0 " ] ) i p of paddle at I' feet 2 iuehcs draft o f vessel, 'B " S " a \ u m h c r of paddles in each w h e e l , . . . . 1.L ~ ' u m b e r of paddh,~ in w a t c r i n c a e h wheel a t 7 feet 2 in. draft, 3. _Area of t w o paddh~s . . . . . . '~'~a~ square tbet. Mroportion of lho ;~rea of t w o padd~es to immersed a m i d s b i p seclion of lmtl, . . . . . 1"000 to 5'802 1-'roportioa of Ihe ar~".~ of nil the immersc~] paddle surlY:tee to immersed a m i d s h i p s c c l i o n o f l m l l , . 1'000 to 1'933 O ~ t ~ : ( ~ x . ~ , I l o l r . ~ : a s . - - ' l ' w o iron d o a b l e r e t u r n drop flue boilers, placed one on each s i d e t h e engine. ],e.l~glh o f e a c h boiler, 16 feet. t3rea&h '" 5 " 6inches. t{eght. " 8 " I " (.,ubw eonte~d~ of cn'cmnscrflnn~ parallelopq)edon o f each boder, 711 :~ cubic tbet. A r e a of the. he:air,g; surface iu the t w o boiler,~, 750 square tbet. grail! " 47 C a p a c i t y of steam room in boilers, . . 584 cubic feet. " " " a n d s t e a m pipe, . 615 " Cro~s area. of each of the t h r e e r o w s o f flues (both boilers), 6.303 sq. feet. C r o s s area of lhc (:hilmle3: , 6.a0a " l t e i g h t of chimney above g r a t e , . . . . 4 a feet 9 inches. M e a n pressure of s t e a m al.,o,.e a t m o s p h e r e p e r sq. in. in boilers, 12} poun&, Initial " " " cylinder, 10.3 " C u t t i n g off at, fl'om c o m m e n c e m e n t o f stroke of piston, 26~ inches, D o u b l e strokes of piston per m i n u t e , . • 14'23 C o n s u m p t i o n ot P i t t s b u r g b i t u m i n o u s coal per h o u r , with na.
•
tural draft,
"
•
•
-
"
"
•
•
°
-
1
564 I)onnds.
j'v'otes on lhe United Slates Steamer Vi.zen.
265
PROeO,tTJOXS. Proportion of h e a t i n g to g r a t e surface, , 15"958 to 1"000 ,' g r a t e zurlixcc to cr,~s area of each of the 3 ro',vs o f f l u e ~ 7..t57 " " " " chimney, 7"457 " " h e a t i n g surface to cross area o f each o f the 3 r o w s o f f l u e s , 118.991 " •' " " chimney, 118,991 " " h e a t i n g surface per cubic foot of space displacem e n t o f piston, 17.685 sq. fi, et. " grate " " " " 1'108 " " t~eafin~ ~urfaec w r cubic tbot o f space di~plae.emcnt <:t"piston, multiplied by n u m b e r o f d o u I,h. >trok,'s(11'2.3) per minute, . 1.24~ " ,' ~"r~*t ~ l r f a c o per cu] ic lbot of space di~plaeememt , f 1,ist,m, multiplied by n u m b e r ( 1 4 . 2 3 ) o f do~lbh, strokc~ per minute, • 0"078 " t'ubic fi.ot of .~t~'am ,'oom per cubic foot of steam u s e d per s coke o | ' l ~ i : i , , n . . . . 31"5~7 C o n s u m p t i o n of bituminous P i t t s b u r g coal per ~quarc tbot of g r a t e stir(ace pcr h o u r with n a t u r a l draft, . lg pounds. Con,mmption of tfitmlfinous Pitt:dmrg coal lwr square fi~ot of hv:tling surfact' per h o u r with lmtural draft, • 0.752 " Sea water evaporatett by or~e sq. [L c~f heafin~ sllrfacc per hollr, " " m;e pound of Pittsburg b i t u m i n o u s coal per h~ur, . . . . .
,
q'hese boilers, (Plate ]l,) under ordinary steaming wouhl funaish steam enough at rite above pressure to cut off"at ]aalf stroke; the piston of course making a proportionally ir:creast'd number of strokes; the coal is reported as of very i:ffL'riorquality. ]:)I.:RI"OI,:.MANCE WITH TIlE OII, IGINAI, B O I L E R S .
The following results are the mean of 311 hours steaming in the Gulf of Mexico, during the months of February and March, 1851, embracing the usual variety of wind, sea, dip of paddle, mid vessel's draft of water. The boilers were six years old, m'd very foul with incrustation. Steam pressure in boiler above atmosphere per square inch, 12~ pounds, cutting off at .06} inches from the commencement of the stroke, giving a mean effective pressure by indicator of 16 pounds per square inch of piston; number of double strokes of piston per minute, 14'23; actual horse power developed by the engine, 86'266. The speed of the vessel was 6.5:2 knots of 608"2§ feet, or 7"511 statute ,miles. The diameter of the circle of the centre of reaction was 17~ feet; the circumference normal to which is 54"19 f~et; and 5 I- 19 X 14,2 3 M fit;,: 462 ~;7.4~ l b e t = speed of centre of reaction of paddle~ per hour. 6 0 8 2 ~ X 6 ' 5 2 = 3 9 6 5 ~ ' 9 9 f i w t = s p e e d o f vessel per hour. 6f;08.43 f e e t = s l i p of centre of reaction o f paddles per h o u r . or, 14'28 per cent.
The oblique action of the paddies, calculated as the squares of the series of'their angles of incidence on the water, is 1!'94 per cent. Total losses o1" effect by the paddle wheels, (14-'28+11'94) 26"22 per cent. The evaporation was ol)tained as follows: The steam being cut off"at ~26.~inches from the commencement of the stroke, there was filled per stroke, 15"507 cubic fi~etof the cylinder, to whichmustbe added 4 cubic "VoI,. XXIII.~'.Plliax~ Smtil:s.-~No. 4 . - - A r a x ~ , 1852.
2:3
266
.Mechanics, Physics, and Chemistry.
feet comprised between the cut-off valve (which was also the steam valve,) and piston, including clearance, nozzles~ &e.~ making 19'507 cubic feet of steam of the total pressure of 25 pounds per square inch; the initial cylinder pressure being 1.7 pounds less than the boiler pressure. There would consequently be furnished per hour, (19"507X'28"46 x 60) 33349"168 cubic feet of steam of that pressure; and as the relative volumes of steam of the density due to that pressure and water are as 1044 to 1, there would be evaporated (33349"168@1044) 31"943 cubic feet of water. Taking the cubic foot of sea water at 64"3 pounds, there would be evaporated per hour, by one pound of Pittsburg bituminous ,31"943X64"3, coal, ( 5~d4...... ) 3'642 pounds of sea water; to this must be added the loss by blowi~W o.ff at -~ of Sewell's Salinometer, obtained as follows: the total heat of steam being taken at !"202 ° F., the temperature of the feed water fi'om the hot well at 100 ° F., the temperature of the steam and water in the boilers at 241 ° F., and one-half the water pumped in the boilers being bl(?wn out; the% 1~°02°--100°~1102°~ the heat used in evaporating the water; and 241°~100-=141 °, the heat used in blowing o{/, hence, 1102°-1-141°=4243 °, the total heat used and lost, and 141 is 11.34 per cent. of 1"243, leaving the complement of 100 per cent.~ or (100--11'34) 88"66 as the proportion of the total heat evolved from the fuel applied to the evaporation of the water; and as this 88"66 per cent. evaporated 3"642 pounds, 100 per cent. would evaporate 4"1.07 pounds. 'the evaporation then by one pound of Pittsburg bituminous coal per hour, would be 4"107 pounds of sea water. Increasing the total weight of water evaporated, in like manner, by the same per centage for loss by blowinN" o~, and we have the total evaporation of 36.0"29 cubic feet, or 2316'64"pounds of sea water by 750 square ibet of heating surface, being 3"089 pounds of sea water per square foot. The original boilers having become corroded out a air of the Mo tgomery ve~'tieal tubular boilers (Plate III,) were substituted in 1851. n PERFOIlh~IANCE WITH TItE MONTGOBIEt~.Y BOILERS.
The following performances of the Montgomery boilers are taken fi'om lhe Vi:ren's steam log, kept during a passage fi:om Pensacola to Key West, Florida. On this passage both Cumberland bituminous and anthracite coals were used. In both cases, the conditions of wind and sea remained sensibly the same; the wind and swell were moderate, and abeam. The boilers being nearly new, were clean and free from incrustation. The Cumberland bituminous was used for the first half of the passage, and the anthracite for the last half, with natural draft in both cases. PEIWOIRMANCE
Wl~?H TIIE CUMBERLAND.
Mean speed of vessel per hour, 6"64 knots; double strokes of piston per minute, 15"675; vacuum in condenser per gauge 26 inches of metcur),; steam pressure in boiler per square inch above atmospher% 14'67 pounds, cut of[ at 36 inches from commencement of stroke of piston; pounds of coal consumed per hour, 6"/6; sail used half the time. PERFORMANCE WITH THE ANTHRACITE.
Mean speed of vessel per hour 5'95 knots. Double strokes of piston per minute 14"88; vacuum in condenser per guage 26 in. of mercury. Steam
.]rotes on the United Slates Steamer Vixen.
267
pressure in boiler per square inch above atmosphere 14'75 pounds; cut off at 36 inches from commencement of stroke of piston. Pounds of coal consumed per hour 713. Sat[ used one-third the time. It was extremely difficult to keep steam with anthracite after the first 2-i hours; with Cumberland coal, steam was kept more easily, but after three or four days continuous steaming with it, the spaces between the tul)es would choke up, and so impair the draft as to render it necessary to stop the engines, draw the fires, cool the boiler, and clean out the tube spaces. During an attempt made to steam from Pensacola to ;New Orleans with Pittsburg bituminous coal, the tube spaces choked completely up in 24 hours, so as to wholl) destroy the draft, the flame rushing out into the fire room whenever the doors were opened, and the vessel put back to Pensacola, reaching port with difficulty. With these boilers, there is required about an hour and a quartei~ to raise steam ti'om sea water of Gulf temperature, say 60 ° F. Calculating the evaporation by the Cumberland coal in the same manr.er as befbre, there results an evaporation of 5"237 pounds of sea water l>er pound of coal per hour, and 3"248 pounds of sea water per square I5ot of healing surface per hour. Proceeding in the same manner with the anthracite, there results an evaporation of 4"713 pounds of sea water per pound of coal per hour, and 2'7~9 pounds of sea water per square foot of heating surface per hour. 3 [ o x ' r o o . ~ : u ' ; B o u . r : ~ s . T w o of iron, p l a e c d one o n each side the e n g i n e . I , e n g t h of each boiler, . 13 feet 9 inches. l~,-eadth " 5 " 6 " Ifcight ,, . . . . . 7 " 9 " C u b i c c o n t e n t s of c i r c u m s c r i b i n g p a r a l l e l o p l p e d o n of e a c h boiler, 586.09 cubic feet. A r e a of the g r a t e sm'ib.cc in the two boilers, 53.60 square feet. " heating " " 1090"00 " C apacity of s t e a m r o o m in boilers, . 890"00 cubic feet, " " " a n d s t e a m pipes, 425.00 " C ross a r e a of side flue, both boilers, . • . 7"56 s q u a r e feet. s p a c e s b e t w e e n tubes above division plate or d i a p h r a g m (both boilers), 7 . 6 4 " " " " below, " " 7"03 ~ " smoke chimney, . 8.73 " H e i g h t of snloke c h i m n e y above grate, • 4 8 feet. M e a n pressure o f s t e a m above a t m o s p h e r e per square i n c h in holler, w i t h C u m b e r l a n d coal . . . . 14-67 p o u n d s . Initial pressure of steam above a~mosphere p e r s q u a r e i n c h in cylinder w i t h C u m b e r l a n d coal, . . . 12.47 " C u t t i n g offat, f r o m c o m m e n c e m e n t o f stroke o f piston, . 3 feet. Double strokes of piston p e r minute, wltb. C u m b e r l a n d coal, 15.675 C o n s u m p t i o n of C u m h e r l a n d coal p e r h o u r w i t h n a t u r a l draft, 676 pounds. M e a n pressure o f s t e a m a b o v e a u n o s p h e r e per s q u a r e i n c h ift boiler, w i t h a n t h r a c i t e . . . . 14'75 " Initial pressure of steam above a t m o s p h e r e p e r square i n c h in cylinder, . . . . . I~.55 " C u t t i n g off at, f r o m c o m m e n c e m e n t o f stroke o f piston, 3 feet. Double strokes of piston per m i n u t e w i t h a n t h r a c i t e , 14.88 Co~asumption o f a n t h r a c i t e per h o u r with n a t u r a l draft, 718, PItOPORTIO~S,
P r o p o r t i o n of h e a t i n g to g r a t e surface, . " g r a t e surface to cross a r e a of side flue, • " " " s p a c e s , between "
tubes above diaphragm, below "
~ 0 ' 3 3 6 to 1"000 7.090 " 7.016 7"624
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