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Proofs relating to Mr. Woolf's invention of applying high pressure steam expansively
134
I[(qh Pressure Steam Expansivel?].
have occasion to lament such a melancholy disaster as that "which has occasioned our present labours. B. SILLIMAN, Professor of Chemistry, &c., Yale College. "~/V. C, REDr'IELD, Engineer, and Agent of the Steam Navigation Co. of New York. ~_)ENISON OLMSTEAD~ Profcssor of IX.'aturalPhilosophy, &c., Yale College. I)AN1EL COPELAND, Engineer, ~md Manufacturer of Steam l,h~g'ines,Hartford. JOhN F. LAwsm,': l':,nginecr of the Steam-boat Chief Justice Marshall. J~¥w IIaven~ November 27th~ 1833.
Proofs vdating to Mr. I4Zoo~"s Invention of applyin,ff tligh Pressure Steam Expansively, (Continued from p.
55.)
In 1816, an entire new engine was made at Dolcoath mine~by Messrs..teffery and Oribble, to work with high pressure steam acting expansively, on Mr. Woolf's system, in one cylinder of seventy-six inches diameter; it answered extremely well, although it never did so much as the engines with two cyli,aders had done, whiIst they were new and in good order; but as they materially fell off in 1817, and 1818; when they got out of order, and as lhe Dolcoath engine kept up a steady perfbrmance ot about tbrty millions, the use of one cylinder for Mr. Woolf's system obtained the preference ; and in a short time after Mr. Woolf's patent expired, most of the old Boulton and Wart's engines in Cornwall were altered to work by high pressure steam on hissystem ; some few had an extra cylinder added, but commonly the old cylinder was retained. The advantage of the change from how pressure to high pressure, on Mr. Woolf~s system, was manifest in all cases; but it was greater or less, according as the steam was used stronge,', and with more or less expansive action. All the new engines since erected in Cornwall have been madeexpressly to work on Woolf's system~ and always with one cylinder~ excepting one instance of two cylinders. In 1820 Mr. Woolf made two engines tot tt,e Consolidated mines, each with one cylinder ninety inches diameter; but as neither of thos% nor the Dolcoath engine: ever did so much as the engine with two cylinders had done at firsh Mr. Woolfstill felt inclined to prethr his original plan. Accordingly in 18.o4, having undertaken to make two large engines at Wheal Alfred, he prevailed on the adventurers to go to the expense of mak. ing one of them with two cylinders, of forty and seventy inches diameter, the other engine being the same as those at Consolidated mines, with one cylinder ninety inches diameter; both engines were worked with high pressure steam. T h e performance in 1825, averaged 40.01 millions with two cylinders~ and 42.15 with one cylinder: this was
High Pressure Steam Expansively.
I85
considered decisive against two cylinders;* and no engines have since been made in Cornwall, either by Mr. Woolf or others; except with one cylinder, to work on his system. The l)ertbrmance of those engines was very slowly and gradually incveased~ as appears by the tbllowing annual averages of the highest peribrmances that are to be tbund amongst them each month. Until 1826, their performance remained below that of the first engines with two cylinders~ in 1816~ which then averaged 46.97 millions. Previous to 18:26, the steam cases of the cylinders were not clothed~ but exposed to the air. Years.
Millions.
~/ears.
Millions.
1816 ]817 181.8 1819 18:20 £1821
363 41.6 39.3 40.0 41..,,'}
42.1 42,5 45.4 45 "2 59.7
1822
4'2.5
1823 1824 1825 ] 826 1827 18"28 18"29
42,8
77.3 76.2
The advance made in 1827, and since that tim% has been effected by good management of the engines, chiefly by clothing all the steam vesscls~ and thus preventing any needless waste of heat by r a d i a tion; also by using better boilers;t but the engines are slriclly according to Mr. WoolPs system of high pressure acting expansively in one cylinder. Great credit is due to Captain Samuel Grose, who began the race of improvement in management; first, in an engine which he made at Wheal t lope~ in 1825~ and still more in another which he made the next year at Wheal Towan, with an eighty inch cylinder; in 1827, it averaged 58.18 millions, its highest being-62.22 in July. At the end of 18`27~ Mr. Woolf removed the ninety inch cylinder engine before mentioned, at Wheal Alfred, (that mine having ceased working,) to the Consolidated mines~ and by good management and clothing, it raised G4.42 millions on tim average of the last three months, the highest being 6%10 in :November. In 1828, CaptaiB Grose brought the annual average performance of Wheal Towan engine to 77.29~ the highest being 87.05 millions; in * The engine with two cylinders had boilers on a complicated plan, which did not answer well, and the other engine had very good boilers. If both eng'ines had been worked with equally good boilers, the two cylinders would have made the hest performance. t See Mr. Taylor's paper on these boilers, Phil. Mag. and Annals, N. S. vol. i. p. 126; they are long. cylinders, containing cylindrical tubes within them tbr the filrnaees; on a plan which was first brought into use tbr hig'h pressure steam by Mr'. Trevithiek, in 1804.
13(i
High Pressure Steam Zxpansivel~j.
April,* Mr. Woolfls engine averaged 62.572 and its highest was 67.56 millions in May. T h e s e striking examples stimulated the e:(ertions of ;d! the Cornish engineers to take the same c a r e in management s and with such success that the a v e r a g e of all the engines in 18291 was ,tl.22 millions ; although in 18141 before Mr. Woolf~s system was begun~ it was only 20.371 or less than half: T h e number or" engine% and the p o w e r exerted by them I is more than doubled~ whilst the quantity of coals consumed by them is sel;sibly lessened. T h e importance of such an increase of p o w e r from the same fuel~ to the success of mining in Cornwall, may be estimated by the following account of the Consolidated and United mine% which are worked by one company o[" adventurers~ and form the largest mining establish. meat in existence. T h e United mines are worked to a loss 1 and are only k e p t drained to about one-third of their depth~ in order to cut off some water ~vhich would otherwise flow into the Consolidated mines. T h e s e mines have been more productive during the last seven years~ than the average of mines it:. Cornwall. T h e tbllowing particulars are collected frora the accounts which h a v e been printed annually in a series of reports by Mr. John "Faylor, and from the monthly reports on the engines. T h e Cousolidaled mines reeommenced working in 18191 after laying drowned for fourteen years 1 an.d 65,000l. was advarmed by the new adv~mturers~ to bring them into operation. During the years IN19. ]N2t), and l,S2l~ the expenditure e x c e e d e d the returns by 7,1,07S/. ; but during the years 1822~ 1S231 and 1824~ a profit ot 5115(il/. was made. At the cml of 1824, i0,000/, more was subscribed to continue the United mines, which were given up by their original proprietors. "l.'he capital to be repaid to the adventurers at the beginning of 1825~ including interest then due upon the several advances, was 55~382l. ])urin~ the last tlve years~ the Consolidated and United mines toget h e r have produced a profit of 63~604/.; whereby all the capita! sub. scribed, together with interest upon it 1 has been paid off~ and an ac. tual gain was made in 18291 in addition to the value of the stock of materials on the mines. T h e total expenditure in all the eleven years I has been 824~585/.1 and the returns 865.672I.; hence the prollt beyond the r e p a y m e n t of the capital subscribed~ has been 41,037l. in e l e v e n y e a r s ; or interest at llve per cent. per annum being allowed on the sums subscribed, until the periods of ref)ayment ~ the clear gain is stated~ in the printed acc(mnls~ to be only 10,244/. Io the adventurers.] T h e expense of draining the water from both mines 1 as stated ia ~* See Mr..Iohn TayIor's accmmt of the pcrforrnance of this eng'ine in May, 1830, when, on an accurate tri:~l ()[ about two hours and a h'df working', it raised 92.35 millions. "~ This does m)t include any valualiou of the materials in use in the mines, althou.~h the cost of all materials is inchtded in the amount of l:otal expenditure. The maierials would sell for a larg'e sum, but that can scarcely be reckoned as a part ofthe profit, because fi'om Ihe uncertainty of mining prospects, a mine cannot be given up in time to realize it: the working is usually continued at a
High Pressure Steam Expaneively.
137
the annual accounts for the last five years, has been decreasing each year from 17~776L to 11058L per annum; although the monthly reports on the engines show that the number of engines has been increased from four to eighl, and the power exerted by them increased from 432 to 51:3 horse power. T h e cost of drainage has averaged 13~826L per annum. T h e average performance ot the engines has been improved from 30.04 to 51.81 millions, during the last five years, averaging 39.36 million..; being more than double 19.38 millions~ which was the average pertbrmance of Mr. Watt;s engines in 1813~ when Mr. Woolf went into Cornwall; there£ore~ if such engines were now used at the Consolidated mines, the expense of drainage might he exp~eted to average (13,826/. X 39.q6 +19,;:18 ---~) 28,100/. per annum, or 1t,L)74l. more than it has been ; and it is that saving which has constituted the whole of the prolit during the last five years. I)uring the last five years the mines have produced 73,56t tons of copper or% which on ;m average.~ hasyiehled nine and a half percent. of copper, arm thirty-six and a halt'tons of tin ore. The ores have been sohl for 548~872l., of which one lwenly-tburth has been paid to the lord of the soil as rent. The total cost of working the mines has been 4'26, 444L, leaving a clear profit of 63fi04L The above is but a limited view of the adwmtages arising from the use of' Mr. Woolt's engines; for if the mines had,been begun in 1819, with Mr. Watt~s engines~ the loss during the first years would have been considerably greater than it was~ and the mines would have continued to be unprofitable for a longer time than three years; also the subsequent profit would have been so much smaller than it has been, that it would not have repaid the previous loss (and interest upon the capital advanced) tbr a long time to come, beyond the present date, supposing the mines to continue to yield ore. In fact, it these mines could have been worked with l)roIit by 51r. Walt~'s engines~ they would not have been given up as they were, twenty-live years :,go, when they were not worked out so deep, or so extensively, as they are now. i Eng-incs and cost of draimLge at the Const~lidatedand United Milles. at , No. of' lorse Average t Cost of ] clear Expense D e. tFng.ines ~,ve~ Millions' !drainag'e.I profit, saved. 18~5 1826 1827 1828 18~9
S1.04 o~.51
£177761 £4169 £98~4
t [ [ I f
4 6 8 8 8
4S2 4~ 978 526 515
44.86 51.81
134~61 13e.94 11e54 lO~4281 2°~314 1545~ 119581 16179 1904 ° '
t Avers.l
7
I 454
59.8()
~t58201:~1~7~1 ~1~278~i
36.76
l o 5 4 0 1 7648
8007
loss until a dcbt is incurred, and when the adventurers become too much discouraged to make fitrther advances, the minc is givcu up, and the materials sold to pay the debt. VoL. X I I I . - - N o , ~.--F~mtualtr, 1834. 18
13S
h'on Steam-boats.
'.['he last column of the table shows the saving that has been made by the nse of Mr. WooWs engines, or the increase in the cost of drainage that would have been incurred by using" Mr. Watt's engin% raising twenty millions, instead of the engines actually used; those savings are included in and form part of the profits, and without them the extra expense would have absorbed more than all the profit in 1,q25~ 1826, and in 1829, so that instead of profit the adventurers would have lost 5,655l. in 18f25~ 689l. in 18~6, and ~o,863l. in 18"29. Or, taking the whole o{"the last five years, no profit would have been made ; and it would have been more advantageous to the adventurers to have btoken up their establishment~ and sold the material% than to have continued working. In conclusion, it may be safely asserted that the saving in fuel resulting from the general use of Mr. WoolPs system of working steam engines by high pressure steam acting expansively, (instead of Mr. Watt's system oi" woridng them by low pressure steam acting expansively~) constitutes the present profits of deep mining in Cornwall. JOIIN FARE¥,
London dune 5, 1830.
[ Rep. Pat. lay. ./]n dnti.Sediment.
The substance emplnyed here (Craighall Colliery,) is known by the name of comings, being the radicles of barley, produced in the pro. cess of malting, wlfich are separated before the malt is sent to market. About a bushel of these is thrown into the boiler, and when the steam is again raised, an immediate ettect is visible, for there is not only a plentiful supply of steam to produce the full working speed of the engine, but an excess of it is going to waste at the safety valve. "finis singular effect will continue several days. Such is the fact ; but the principles by which the vegetable matter acts are not very nbvious, as it is doubtful whether it acts chemically nr mechanically; if its ac. tion is mechanical, chatt" or saw dust may produce the same eit~ct.--
Mi/ne's Practical Uiew oat"the Steam Engine. ~Mech. Mag.
The Iron Steam-boat 3lburkha, This vessel is now in the river Niger, with the Quarra steam-boat, and seems to have been tile t:avourite of the two vessels since they de. parted on their interesting expedition. The advantages of iron vessels in warm climates, are ably pointed out in a short extract we gave in our last number t'rota Chambers' Journal; and these advantages seem to be in no wise exaggerated in the instance of the Alburkha~
I[(qh Pressure Steam Expansivel?].
have occasion to lament such a melancholy disaster as that "which has occasioned our present labours. B. SILLIMAN, Professor of Chemistry, &c., Yale College. "~/V. C, REDr'IELD, Engineer, and Agent of the Steam Navigation Co. of New York. ~_)ENISON OLMSTEAD~ Profcssor of IX.'aturalPhilosophy, &c., Yale College. I)AN1EL COPELAND, Engineer, ~md Manufacturer of Steam l,h~g'ines,Hartford. JOhN F. LAwsm,': l':,nginecr of the Steam-boat Chief Justice Marshall. J~¥w IIaven~ November 27th~ 1833.
Proofs vdating to Mr. I4Zoo~"s Invention of applyin,ff tligh Pressure Steam Expansively, (Continued from p.
55.)
In 1816, an entire new engine was made at Dolcoath mine~by Messrs..teffery and Oribble, to work with high pressure steam acting expansively, on Mr. Woolf's system, in one cylinder of seventy-six inches diameter; it answered extremely well, although it never did so much as the engines with two cyli,aders had done, whiIst they were new and in good order; but as they materially fell off in 1817, and 1818; when they got out of order, and as lhe Dolcoath engine kept up a steady perfbrmance ot about tbrty millions, the use of one cylinder for Mr. Woolf's system obtained the preference ; and in a short time after Mr. Woolf's patent expired, most of the old Boulton and Wart's engines in Cornwall were altered to work by high pressure steam on hissystem ; some few had an extra cylinder added, but commonly the old cylinder was retained. The advantage of the change from how pressure to high pressure, on Mr. Woolf~s system, was manifest in all cases; but it was greater or less, according as the steam was used stronge,', and with more or less expansive action. All the new engines since erected in Cornwall have been madeexpressly to work on Woolf's system~ and always with one cylinder~ excepting one instance of two cylinders. In 1820 Mr. Woolf made two engines tot tt,e Consolidated mines, each with one cylinder ninety inches diameter; but as neither of thos% nor the Dolcoath engine: ever did so much as the engine with two cylinders had done at firsh Mr. Woolfstill felt inclined to prethr his original plan. Accordingly in 18.o4, having undertaken to make two large engines at Wheal Alfred, he prevailed on the adventurers to go to the expense of mak. ing one of them with two cylinders, of forty and seventy inches diameter, the other engine being the same as those at Consolidated mines, with one cylinder ninety inches diameter; both engines were worked with high pressure steam. T h e performance in 1825, averaged 40.01 millions with two cylinders~ and 42.15 with one cylinder: this was
High Pressure Steam Expansively.
I85
considered decisive against two cylinders;* and no engines have since been made in Cornwall, either by Mr. Woolf or others; except with one cylinder, to work on his system. The l)ertbrmance of those engines was very slowly and gradually incveased~ as appears by the tbllowing annual averages of the highest peribrmances that are to be tbund amongst them each month. Until 1826, their performance remained below that of the first engines with two cylinders~ in 1816~ which then averaged 46.97 millions. Previous to 18:26, the steam cases of the cylinders were not clothed~ but exposed to the air. Years.
Millions.
~/ears.
Millions.
1816 ]817 181.8 1819 18:20 £1821
363 41.6 39.3 40.0 41..,,'}
42.1 42,5 45.4 45 "2 59.7
1822
4'2.5
1823 1824 1825 ] 826 1827 18"28 18"29
42,8
77.3 76.2
The advance made in 1827, and since that tim% has been effected by good management of the engines, chiefly by clothing all the steam vesscls~ and thus preventing any needless waste of heat by r a d i a tion; also by using better boilers;t but the engines are slriclly according to Mr. WoolPs system of high pressure acting expansively in one cylinder. Great credit is due to Captain Samuel Grose, who began the race of improvement in management; first, in an engine which he made at Wheal t lope~ in 1825~ and still more in another which he made the next year at Wheal Towan, with an eighty inch cylinder; in 1827, it averaged 58.18 millions, its highest being-62.22 in July. At the end of 18`27~ Mr. Woolf removed the ninety inch cylinder engine before mentioned, at Wheal Alfred, (that mine having ceased working,) to the Consolidated mines~ and by good management and clothing, it raised G4.42 millions on tim average of the last three months, the highest being 6%10 in :November. In 1828, CaptaiB Grose brought the annual average performance of Wheal Towan engine to 77.29~ the highest being 87.05 millions; in * The engine with two cylinders had boilers on a complicated plan, which did not answer well, and the other engine had very good boilers. If both eng'ines had been worked with equally good boilers, the two cylinders would have made the hest performance. t See Mr. Taylor's paper on these boilers, Phil. Mag. and Annals, N. S. vol. i. p. 126; they are long. cylinders, containing cylindrical tubes within them tbr the filrnaees; on a plan which was first brought into use tbr hig'h pressure steam by Mr'. Trevithiek, in 1804.
13(i
High Pressure Steam Zxpansivel~j.
April,* Mr. Woolfls engine averaged 62.572 and its highest was 67.56 millions in May. T h e s e striking examples stimulated the e:(ertions of ;d! the Cornish engineers to take the same c a r e in management s and with such success that the a v e r a g e of all the engines in 18291 was ,tl.22 millions ; although in 18141 before Mr. Woolf~s system was begun~ it was only 20.371 or less than half: T h e number or" engine% and the p o w e r exerted by them I is more than doubled~ whilst the quantity of coals consumed by them is sel;sibly lessened. T h e importance of such an increase of p o w e r from the same fuel~ to the success of mining in Cornwall, may be estimated by the following account of the Consolidated and United mine% which are worked by one company o[" adventurers~ and form the largest mining establish. meat in existence. T h e United mines are worked to a loss 1 and are only k e p t drained to about one-third of their depth~ in order to cut off some water ~vhich would otherwise flow into the Consolidated mines. T h e s e mines have been more productive during the last seven years~ than the average of mines it:. Cornwall. T h e tbllowing particulars are collected frora the accounts which h a v e been printed annually in a series of reports by Mr. John "Faylor, and from the monthly reports on the engines. T h e Cousolidaled mines reeommenced working in 18191 after laying drowned for fourteen years 1 an.d 65,000l. was advarmed by the new adv~mturers~ to bring them into operation. During the years IN19. ]N2t), and l,S2l~ the expenditure e x c e e d e d the returns by 7,1,07S/. ; but during the years 1822~ 1S231 and 1824~ a profit ot 5115(il/. was made. At the cml of 1824, i0,000/, more was subscribed to continue the United mines, which were given up by their original proprietors. "l.'he capital to be repaid to the adventurers at the beginning of 1825~ including interest then due upon the several advances, was 55~382l. ])urin~ the last tlve years~ the Consolidated and United mines toget h e r have produced a profit of 63~604/.; whereby all the capita! sub. scribed, together with interest upon it 1 has been paid off~ and an ac. tual gain was made in 18291 in addition to the value of the stock of materials on the mines. T h e total expenditure in all the eleven years I has been 824~585/.1 and the returns 865.672I.; hence the prollt beyond the r e p a y m e n t of the capital subscribed~ has been 41,037l. in e l e v e n y e a r s ; or interest at llve per cent. per annum being allowed on the sums subscribed, until the periods of ref)ayment ~ the clear gain is stated~ in the printed acc(mnls~ to be only 10,244/. Io the adventurers.] T h e expense of draining the water from both mines 1 as stated ia ~* See Mr..Iohn TayIor's accmmt of the pcrforrnance of this eng'ine in May, 1830, when, on an accurate tri:~l ()[ about two hours and a h'df working', it raised 92.35 millions. "~ This does m)t include any valualiou of the materials in use in the mines, althou.~h the cost of all materials is inchtded in the amount of l:otal expenditure. The maierials would sell for a larg'e sum, but that can scarcely be reckoned as a part ofthe profit, because fi'om Ihe uncertainty of mining prospects, a mine cannot be given up in time to realize it: the working is usually continued at a
High Pressure Steam Expaneively.
137
the annual accounts for the last five years, has been decreasing each year from 17~776L to 11058L per annum; although the monthly reports on the engines show that the number of engines has been increased from four to eighl, and the power exerted by them increased from 432 to 51:3 horse power. T h e cost of drainage has averaged 13~826L per annum. T h e average performance ot the engines has been improved from 30.04 to 51.81 millions, during the last five years, averaging 39.36 million..; being more than double 19.38 millions~ which was the average pertbrmance of Mr. Watt;s engines in 1813~ when Mr. Woolf went into Cornwall; there£ore~ if such engines were now used at the Consolidated mines, the expense of drainage might he exp~eted to average (13,826/. X 39.q6 +19,;:18 ---~) 28,100/. per annum, or 1t,L)74l. more than it has been ; and it is that saving which has constituted the whole of the prolit during the last five years. I)uring the last five years the mines have produced 73,56t tons of copper or% which on ;m average.~ hasyiehled nine and a half percent. of copper, arm thirty-six and a halt'tons of tin ore. The ores have been sohl for 548~872l., of which one lwenly-tburth has been paid to the lord of the soil as rent. The total cost of working the mines has been 4'26, 444L, leaving a clear profit of 63fi04L The above is but a limited view of the adwmtages arising from the use of' Mr. Woolt's engines; for if the mines had,been begun in 1819, with Mr. Watt~s engines~ the loss during the first years would have been considerably greater than it was~ and the mines would have continued to be unprofitable for a longer time than three years; also the subsequent profit would have been so much smaller than it has been, that it would not have repaid the previous loss (and interest upon the capital advanced) tbr a long time to come, beyond the present date, supposing the mines to continue to yield ore. In fact, it these mines could have been worked with l)roIit by 51r. Walt~'s engines~ they would not have been given up as they were, twenty-live years :,go, when they were not worked out so deep, or so extensively, as they are now. i Eng-incs and cost of draimLge at the Const~lidatedand United Milles. at , No. of' lorse Average t Cost of ] clear Expense D e. tFng.ines ~,ve~ Millions' !drainag'e.I profit, saved. 18~5 1826 1827 1828 18~9
S1.04 o~.51
£177761 £4169 £98~4
t [ [ I f
4 6 8 8 8
4S2 4~ 978 526 515
44.86 51.81
134~61 13e.94 11e54 lO~4281 2°~314 1545~ 119581 16179 1904 ° '
t Avers.l
7
I 454
59.8()
~t58201:~1~7~1 ~1~278~i
36.76
l o 5 4 0 1 7648
8007
loss until a dcbt is incurred, and when the adventurers become too much discouraged to make fitrther advances, the minc is givcu up, and the materials sold to pay the debt. VoL. X I I I . - - N o , ~.--F~mtualtr, 1834. 18
13S
h'on Steam-boats.
'.['he last column of the table shows the saving that has been made by the nse of Mr. WooWs engines, or the increase in the cost of drainage that would have been incurred by using" Mr. Watt's engin% raising twenty millions, instead of the engines actually used; those savings are included in and form part of the profits, and without them the extra expense would have absorbed more than all the profit in 1,q25~ 1826, and in 1829, so that instead of profit the adventurers would have lost 5,655l. in 18f25~ 689l. in 18~6, and ~o,863l. in 18"29. Or, taking the whole o{"the last five years, no profit would have been made ; and it would have been more advantageous to the adventurers to have btoken up their establishment~ and sold the material% than to have continued working. In conclusion, it may be safely asserted that the saving in fuel resulting from the general use of Mr. WoolPs system of working steam engines by high pressure steam acting expansively, (instead of Mr. Watt's system oi" woridng them by low pressure steam acting expansively~) constitutes the present profits of deep mining in Cornwall. JOIIN FARE¥,
London dune 5, 1830.
[ Rep. Pat. lay. ./]n dnti.Sediment.
The substance emplnyed here (Craighall Colliery,) is known by the name of comings, being the radicles of barley, produced in the pro. cess of malting, wlfich are separated before the malt is sent to market. About a bushel of these is thrown into the boiler, and when the steam is again raised, an immediate ettect is visible, for there is not only a plentiful supply of steam to produce the full working speed of the engine, but an excess of it is going to waste at the safety valve. "finis singular effect will continue several days. Such is the fact ; but the principles by which the vegetable matter acts are not very nbvious, as it is doubtful whether it acts chemically nr mechanically; if its ac. tion is mechanical, chatt" or saw dust may produce the same eit~ct.--
Mi/ne's Practical Uiew oat"the Steam Engine. ~Mech. Mag.
The Iron Steam-boat 3lburkha, This vessel is now in the river Niger, with the Quarra steam-boat, and seems to have been tile t:avourite of the two vessels since they de. parted on their interesting expedition. The advantages of iron vessels in warm climates, are ably pointed out in a short extract we gave in our last number t'rota Chambers' Journal; and these advantages seem to be in no wise exaggerated in the instance of the Alburkha~