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ON THE TRUE PRINCIPLES OF VELOCITY IN STEAM NAVIGATION.

Fig. 1.

423

[graphic][subsumed][subsumed]

of the water.

(III.) v =

(

KA

KJA'

+

with the current or the tides.

·1) (V−u)

Now, if we would have the vessel run with the same speed as the floats of the paddle-wheels in the line b b, the equation I., must be brought to v = V. in still water, and the two other equations to

v = V + u
v = V-u.

bow, for instance, in an iron steam-boat, against the current, u being the velocity that is, the foremost part of the stem in the water should be as sharp as a knife, if possible; and then carried to the point A, in an angle which will make the hydraulic coefficient of resistance against the propulsion of the vessel as small as trial and experience have shown to be profitable. This coefficient is generally known by K, and has been found in moderate speeds of well-built vessels to be 02 of an unity,-in higher speeds only 0.15 of an unity. The surface of every single float of the paddle-wheels, dipped, or immersed at the same time in the water being A', and the sum of them SA'; the hydraulic coefficient of the resistance of a body in the shape, and of the size of a common paddle-float K' has been established to be 2:5 unities. The equations for the two momentums of the engines with their speed of floats in the line bb, and the resistance of the immersed part A of the steamer together with its speed have been found by theory and practice to be*.

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As v is the velocity of the circumference of the wheel in the line b b, fig. 1, it is also evident, that a short stroke and a large diameter of the wheel are requisites for a great speed, to which the power must be in a true corresponding proportion. Now this can only be obtained by bringing the term

KA
K'SA'

to 0; or v = (0+1) V. etc.

However, K A being a positive quantity, the term K' A' must be infinite; or

1) V. v being

2=

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2.5 unities, and A also a positive determined quantity, as well as fA',we desee that the speed of a vessel, and the velocity of the floats in the line bb, never

+ 1) (V+u) can become equal by any human con

See Navier, Poncelet, and Taffe.

trivance. However, this shows that we must have a great number of floats, in

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It might appear as if a great number of floats would be the most advantageous, but then, we must look to back-water, and the circumstance that the striking floats at the moment they enter or dip in the water, find unbroken water to act upon; so that we may be convinced that floats much closer than at least 1 foot from each other in the circumference of the wheels, and then only with an appropriate shape, would probably not act favourably to the speed of the steamer.

These are the reasons which led me to the construction of Mr. Joest's patent paddle-wheels, in vertical, inclined, and horizontal positions, which have at least double the number of floats commonly used; I always considered loss of time before the floats strike, as a loss of speed and power. Since the specification of Mr. Joest's patent paddles, those eminent engineers, Messrs. Penn and Son, of Greenwich, have almost doubled the number of floats in their beautiful steamers, with oscillating engines, called the Flirt and Coquette. Many other vessels have had also the number of their floats increased.

It is also deserving of observation, that Messrs. Ditchburn and Mare, the wellknown ship-builders of Blackwall, have shaped their fine vessels as much as possible to obtain the coefficient 0.2 or 0·15 of an unity in the resistance of the vessels against propulsion, and I think they are good authorities. Let us illustrate this by an example:

Let A in fig. 1 = 2,6 square metres (as French measure is known every where in Europe I follow it here,) the surface of each float be equal to or 0.33 square metres, and K equal, as stated before, to 0.2 of an unity. K' 2:5 unities. Now only to bring ✅KA

No 2

25

K'SA'

to

we must have, A being equal to

2.6 metres square, ƒA'=2·6

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SA' or the surface of all floats immersed at the same moment = 262,60 square metres, which divided by 0.33, gives us the number of floats at the same time in the water equal to 7.9 or 8 in a round number, i. e, 4 in each wheel.

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8 No2 25

-8-8 0,08 =8

-80.22. = 8-1,76, or nearly = 6,24 metres. Or when the floats have in the line bb a velocity of 20 miles an hour, the vessel will only have a speed of 15 or 16 miles an hour, which is in accordance with actual practice.

Now the diameter of the paddlewheels remaining 12 feet 6 inches, the circumference in the line bb, fig. 1 is= 12 x 3,14 = 37,68 feet, and the number of floats in one wheel being 4 in the water, we have for the number of floats in one wheel 4 x 8 = 32. But if we will have the vessel going with a higher speed, we must bring the quantity KA to a smaller fraction, or make K'SA'

x=

= 2 × 2, 6 =5, 2 etc.

In this case etc.

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KA K'SA'

would be

=

25

37,68 32.

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Further we have

or thereabouts, = 1 foot 2 inches asd istance for the floats in the wheels. In the last case the floats would only be distant from each other 7 inches, and we could scarcely get rid of back water, or make each float strike upon unbroken water entering it. But it is easy to find by trials the maximum and minimum of the best effectual number of floats.

=

When we consider all that has been said and calculated, we find that long floats, which possess the hydraulic coefficient K': 2.5 unities, must be the very best; but the length of the floats is limited by the beam of the vessel, its stiffness, etc.

We will now examine the steam-engine power requisite for fast-running steamvessels.

Let V represent the speed of the boat, and v speed of the floats in the line bb.

The resistance of the vessel against propulsion in still water must then be (Navier) nearly

ON THE TRUE PRINCIPLES OF VELOCITY IN STEAM NAVIGATION.

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=

Horse-power

17

25

=

× 0,52 × 64

P 51 × 0,52 × 64

75

1

1=

75

0,68 × 0,52 × 64

22, 63 horse-power, which should propel a well-built vessel with the requisite number of floats, at the calculated speed of fifteen miles an hour. But as small boats having 20 to 24 horsepower are not yet constructed so perfectly that the hydraulic coefficient K is brought down in their resistance against propulsion, to 0-20, or 0·15 of an unity, these vessels do not run so fast as those which have 30 to 32 horse power, where a good deal of power is also lost by friction, resistance of air, and back-water. The river steamers may, by working out these principles, advance to perfection in some few years, and paddle-wheels will always be their best propellers; but as for canal-boats, (which certainly cause less working of the slopes when propelled with paddles of a great number of narrow floats, than with ordinary paddle-wheels, so that, for instance, with floats in a canal-boat the destruction of the slopes might almost cease;) and in seafaring steam-vessels it is desirable to have other propellers than paddle-wheels, as well for safety as speed.

For sea-faring vessels and canal-boats I propose paddle-wheels A A (see fig 2)

Fig. 2.

425

to be placed in an oblique position, and provided with floats a a a a, according to Mr. Joest's patent, or even ordinary floats, so numerous, and so shaped that they shall always experience equal resistance in the water after their dips, and the weight, which acts more upon the bearings bb, than on those c c. This is the reason for the conical shape given to the paddle-wheels. Each wheel A A' has its own engine, with two inclined cylinders d d and ď ď, and in case of lowpressure engines with condenser and airpump attached to it. But though there must also be more separate boilers for large vessels, the steam must have one general communication, so that the engines may work with the same power upon each of the paddle-wheels. Now both the paddle-wheels may be worked together forwards or backwards, or one alone may work forwards or backwards, and the other be stopped, or one may work ahead and the other astern, so that you can turn the vessel around one point. These paddle-wheels will do well for men of war steamers, as every competent judge may see. The great velocity with which screws, horizontal wheels, and propellers of every description must be worked, is not requisite here, because the wheels within the vessel may be as wide as ordinary wheels, and have the same medium diameter. All these are certainly great advantages in sea-faring and canal steamers.

A. W. BEYSE.

3, Bengal-terrace, April 6, 1842.

STATE OF LABOUR IN THE COAL, IRON, TIN, COPPER, LEAD AND ZINK MINES OF GREAT BRITAIN AND IRELAND, AND IN THE SURFACE WORKS FOR REDUCING THE ORES OF THESE METALS.

[Compiled from the First Report of the Children's Employment Commission, 1842.]

I.-COAL MINES.

The "Coal Measures," as the geological formations comprising the strata of coal are designated, are variously dispersed in the midland, northern, and western portions of South Britain, and in a broad belt of country which traverses the centre of Scotland, from the shores of Ayrshire to those of the Frith of Forth.

The most important of the English midland coal tracts, or coal fields, is that of South Staffordshire, which, lying to the west and north of Birmingham, is remarkable for the extent to which its vast beds are worked, as well for the purpose of smelting the iron ores, which are raised from strata interspersed among the coal strata, as for the consumption of the neighbouring populous towns, which are the seat of the metal manufactures, and for an extensive "land sale," as the supply of the surrounding country with fuel is frequently designated; the country southward, where canals extend, as far as the Thames, being in great part supplied from this region. The Shropshire district of Coalbrookdale, lying midway between Wolverhampton and Shrewsbury, though much smaller in extent, is in like manner the seat of great iron works, and is the source of a supply of fuel for a great part of the vale of the Severn, and the country to the west of it, to the borders of Wales. The Warwickshire coal field occupies a large tract on the north-eastern verge of that county, from Coventry to Tamworth; and the Leicestershire coal field surrounds the town of Ashby-de-la Zouch. The coal of the latter is far more extensively wrought than that of the Warwickshire field; but both being without iron furnaces, their produce is required only for the land sale, which extends southward even through Buckinghamshire to the Thames.

In North Staffordshire, besides the coal field of the potteries, in which there are extensive ironworks at Kidscrew, there is a smaller tract contiguous to the town of Cheadle. The consumption of the produce of both, however, extends little beyond the northern parts of that county.

In the vale of the Trent, between Nottingham and Derby, commences the great coal-field of Derbyshire and Yorkshire, which extends hence northward, and of which the southern, or Derbyshire portion, occupies the eastern side of that county, and extends

at one extremity into Nottinghamshire. Besides supplying with fuel a vast surrounding region, especially to the east and south, in the counties of Leicester, Nottingham, and Lincoln, it has a considerable home consumption in iron-works. The northern, or Yorkshire portion, which is wholly comprised in the West Riding, has extensive iron-works, and supplies with fuel the whole of Yorkshire, except the coast, and even makes some shipments down the Humber for London.

On the opposite side of the mountains which enclose Yorkshire on the west are the great coal-fields of Lancashire, extending southward into the eastern part of Cheshire, and worked to an enormous extent for the supply of the manufactures and the manufacturing and commercial population which have congregated in their neighbourhood and upon their surface, although there is no manufacture of iron native ores.

North of this is the Cumberland coal-field, in which likewise the pits are wrought only for sale, to supply the counties of Cumberland and Westmoreland, and for shipment, chiefly at Whitehaven, to Ireland and the opposite shores of Scotland.

Again crossing the mountains to the eastern side of the island, we find a large portion of the counties of Durham and Northumberland occupied by the coal tract, which, of all the districts having pits wrought almost wholly for sale, and only to a very small extent for the manufacture of metals, is by far the most important. It supplies not only the whole of those counties, the North Riding of Yorkshire, and the contiguous Scottish counties, but the whole of the eastern and southern coasts of England as far as Cornwall, including the metropolis itself, and the great south-eastern region, into which the sales of the inland coal-districts do not penetrate, because of the greater cost of land-carriage and the want of canals. The export to foreign parts is likewise very extensive; and the whole region is so important as to have rendered necessary, for the purposes of investigation, its division into two districts; that of South Durham, south of the river Wear, and that of North Durham and Northumberland, comprising the rest of the field.

The Coal Districts of the East of Scotland encircle the Firth of Forth in tracts of very irregular form, occupying large portions of the counties of East Lothian, Mid-Lo.

STATE OF LABOUR IN THE MINES OF GREAT BRITAIN AND IRELAND. 427

thian and West Lothian, of Stirlingshire, and part of Dumbartonshire, of Clackmannanshire and Perthshire; and of Fifeshire, in the districts of Dunfermline, Kirkaldy, Cupar, and St. Andrews; the coal of the whole of these districts is extensively wrought, chiefly for land sale to Edinburgh and the surrounding counties, though partly for shipment coastwise, and for the celebrated ironworks of the Carron Company in Stirlingshire.

Lanarkshire, Ayrshire, and Renfrewshire comprise nearly the whole of the irregularly scattered coal-fields of the West of Scotland, and their mines have been chiefly wrought, like those of Lancashire, for the supply of the manufacturers, and of the great manufacturing and commercial population which have seated themselves upon their surface, or in their vicinity, with Glasgow for a centre; but of late years the district of Airdrie, to the east and south-east of Glasgow, has so rapidly extended its importance in the manufacture of iron from the excellent ores there found, as greatly to have augmented the working of its coal for that purpose also.

Returning southward, we find, on the eastern border of North Wales, in the counties of Denbigh and Flint, where they border upon Cheshire, a large coal-field, heretofore possessed of considerable iron-works, which, however, seem now to be sinking before the competition of those in the West of Scotland, and other districts: it still, however, supplies with fuel nearly the whole of North Wales, and a large portion of Cheshire and Shropshire.

But the greatest coal-basin of the West is that of South Wales, which, commencing in the politically English county of Monmouth, occupies a considerable portion also of the counties of Glamorgan, Carmarthen, and Pembroke. The internal consumption of its coal in the manufacture of its native ores of iron, and of those of copper and tin brought from Cornwall and other parts, is enormous; and besides supplying with fuel the whole of south Wales and its borders, Cornwall, and a considerable part of Somersetshire, it exports large quantities of stone coal, even to London.

The Forest of Dean is a singular detached coal field in Gloucestershire, between the confluent rivers Wye and Severn, in which pits are wrought for the manufacture of its excellent iron ores, and for the supply not only of the contiguous parts of Herefordshire and Gloucestershire, but also for a considerable land sale eastward towards Oxford.

South Gloucestershire is, in great part, occupied by a coal field which extends northward from Bristol, and supplies that city and the contiguous country with fuel.

It is for a similar land sale that the valuable mines of north Somersetshire, on the other side of the Avon, are wrought; the principal being those to the south-west of Bath, which not only supply the contiguous country, but have an extensive sale eastward in Wiltshire and Berkshire.

Of the comparatively unimportant coalfields of Ireland, the principal are those of Castlecomer in Kilkenny and the Queen's County, where pits are worked for country sale by three proprietors; that near Killenaule, in the county of Tipperary, where there are three pits worked by the Mining Company of Ireland; and that of Dromagh and Dysart, in the county of Cork, where there are pits worked by Messrs. Leader. There are also a few pits at Drumglass and Coal Island, in the county of Tyrone, which, with the Arigna coal pits at the northern extremity of Roscommon, supplying some contiguous iron works, complete the list of the Irish coal mines which are now worked.

From a great mass of evidence collected, respecting the practices of these various collieries, the Commissioners have been led to the following conclusions :-

1. That instances occur in which children are taken into these mines to work as early as four years of age, sometimes at five, and between five and six, not unfrequently between six and seven, and often from seven to eight, while from eight to nine is the ordinary age at which employment in these mines commences.

2. That a very large proportion of the persons employed in carrying on the work of these mines is under thirteen years of age; and a still larger proportion between thirteen and eighteen.

3. That in several districts female children begin to work in these mines at the same early ages as the males.

4. That the great body of the children and young persons employed in these mines are of the families of the adult workpeople engaged in the pits, or belong to the poorest population in the neighbourhood, and are hired and paid in some districts by the workpeople, but in others by the proprietors or

contractors.

5. That there are in some districts also a small number of parish apprentices, who are bound to serve their masters until twentyone years of age, in an employment in which there is nothing deserving the name of skill to be acquired, under circumstances of frequent ill-treatment, and under the oppressive condition that they shall receive only food and clothing, while their free companions may be obtaining a man's wages.

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