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Mechanics' Magazine,

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

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PORTABLE AIR-STOVE AND VENTILATOR.

PORTABLE AIR-STOVE AND VENTILATOR. Sir, Having personally had painful experience of the evil effects of want of due ventilation in crowded workshops, more especially where particles of metallic dust are flying about, and stealing their way into the lungs, I am induced to send you a plan of a portable air-stove and ventilator, by the use of which in such places the atmosphere may at all times be kept perfectly pure and wholesome. I showed a working model of it, about three years ago, to an eminent physician, who thought it would be equally applicable to hospitals, lazarettoes, &c., and that it might be introduced there with very great advantage.

The lower figure exhibits an elevation of the apparatus, on a scale of a inch to a foot; and the upper one a crosssection, on a scale one-third larger.

A is a common cast-iron stove, such as is used in laundries, &c. The fuel may be either coal or coke. The heated air, &c. rises into an inner wroughtiron cockle marked G, whence the smoke escapes through the pipe or opening H. This cockle has an outward casing 1 I, of about 4 inches in diameter, round which a stream of air is driven in the direction indicated by the arrows, from the fanner B, and issues in a warm state at the mouth of the pipe K. There are two shutters J J, on each side of the cockle, to compel the stream of air to pass over the top of the cockle. LLLL is an iron frame, which supports the cockle, and contains the fanner. PP are doors by which to clean out the cockle occasionally. QQQ are stays, or supporters to the cockle. R is packing or false bottom, to prevent the radiation of the heat. D and C are the wheel and pulley-sheave by which the fanner is worked. They may be turned by hand, or any other convenient power, at the rate of from 200 to 250 revolutions a minute. M is a pipe, by which a supply of cold fresh air may be conveyed from the outside of the building to the fanner. The whole apparatus may be placed on a wooden frame, with only a few bricks for the stove to rest upon.

The large brick air-stoves, invented by that eminent mechanic, Mr. Strutt, of

Derby, are on the same principle as the present. We have six of these at work at the mills where I am employed. I only claim the credit of making them portable, and all of sheet-iron, except the wooden foundation and wheel.

Such portable air-stoves would be particularly serviceable to architects, builders, &c., and might be lent for hire for 4s. or 5s. a day, in the same way as engine-makers are in the custom of letting out their copper pumps to well-sinkers.

I remain, Sir,
Your obedient servant,
WILLIAM REED.

Imperial Paper Mills, Peterhoff,
New Year's Day, 1834.

THE AMERICAN PRACTICE OF WORKING THE ENGINES OF STEAM-VESSELS SEPARATELY.

We extract the following interesting information, on this head, from a letter of Mr. Armstrong, the captain of the "John Bull," which plies between Quebec and Montreal, to Nath. Gould, Esq., Deputy Chairman of the North American Land Company, published in the Nautical Magazine:

"The arrangement is simple, and depends entirely on the separation of the two engines; one of which drives the wheel, and between which there is no connexion whatever; except that in general both boilers are connected with the steam-pipes of each engine, in order to equalise the supply of steam. It will be clear to you that, under this ar rangement, either engine, and consequently either wheel, may be worked a head, reversed, or stopped, independently of the other. This mode of applying the power of steam is entirely different from that adopted in England. There the feeling in favour of the connexion of the two engines is so strong, that the remaining engine is considered as nearly useless after its partner is disabled, whereas no inconvenience has yet been found here to result from the want of the connexion. Each engine works as easily, and passes the centre as well, as it could do if connected with the other, and may be stopped or reversed while the boat is under full speed, without any difficulty or danger. I may compare the steamer to a small row-boat with two oars, one backing and the other pulling, and vice versa, or both forward or both backward, as the occasion may require. The advantages of this arrangement in a

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Sir,-The arrangements represented in the above figures will show that the steam-boat machinery, described in Number 513 of the Mechanics' Magazine, may be still further simplified, and put up in a more compact way, than it is there represented.

Fig. 1 shows the line of shafts running across the vessel; fig. 2 is an end-view of the same. In fig. 1, aa and b b are the short shafts, with two cranks on each, that work on the top of the cylinders; the cranks on a a are set at right angles to the cranks on b b. The shaft c drives the one paddle, and the shaft d works the other; ee and ff are the perpendicular lines passing through the centres of the cylinders; and the lines g, h, i, k, mark where the connecting-rods work; Im is a bolt, with a nut and ruff at each end, for connecting the pin of one of the cranks on the shaft a a with the pin of the crank ou bb, that is next aa. By connecting the shafts in this way, we get quit of the intermediate shaft, with the two cranks on it at right angles to each other, for connecting the two engines, and also of the framing-work which supports it; and the engines take up less

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THE STATURE AND WEIGHT OF MAN AT DIFFERENT AGES.

other cylinder; the lines a b and a c are at angles of 221° to the perpendicular line ad. The cylinders have no declination in the breadth way of the vessel, but are set at rather more than one half of the diameter of the piston-rods, off the perpendicular plane, passing fore and aft the vessel through the centre of its breadth. In this method, only one shaft with two cranks on it is needed; the engines take up just one-half of the room in breadth, and no more in length than in the other methods. The centre lines of the cylinders are not exactly in the centre of the breadth of the vessel, to allow the piston-rods of both engines, where they pass each other at the crank shaft above the cylinders, to work clear of each other.

To obtain an almost equable motion, without a fly-wheel, we must have three cylinders; one upright, and placed exactly below the crank-shaft; another perpendicular to the crank-shaft, and inclined to the first cylinder at an angle of 60o; the

third is also perpendicular to the crank-
shaft, and it is placed at an angle of 60o
to the different side of the first cylinder;
so that the second and third cylinders are
inclined to each other at an angle of 120o.
The plane, passing through the centres
of the piston-rods of the first cylinder,
should bisect the crank-shaft on the top
of the cylinders; the plane passing
through the centres of the piston-rods of
the second cylinders, should cut the
crank shaft a little to the one end of the
shaft; and the plane passing through the
centres of the piston-rods of the third
cylinder, should cut the crank-shaft to-
wards the different end, from the one cut
by the plane passing through the centres
of the piston-rods of the second cylinder.
Setting the cylinders not exactly oppo-
site each other, in this way, lets the
piston rods work past each other.

I am, with respect, yours,
JAMES WHITELAW.

Glasgow, Feb. 7, 1834.

THE STATURE AND WEIGHT OF MAN AT DIFFERENT AGES.

M. Quetelet, of Brussels, has lately published the results of his investigations on the development of the weight of man, his growth, his inclination to crime, the succession of generations, &c. He proposes, hereafter, to publish new inquiries concerning the strength, swiftness, and other qualities of the human species; inquiries which, in order to be exact, must be made by many associated observers, and upon a great number of individuals.

The observations of M. Quetelet were made at Brussels, in the Maternal Ho

WEIGHTS.

spice of St. Peter. He compares them with those made at Moscow and Paris, in similar hospices, and he finds little difference between the means obtained. Unfortunately, the Russian and French practitioners have not distinguished, with as much care as M. Quetelet, the sex, the stature, and the weight of children observed at their birth. This renders the results less capable of minute comparison.

M. Quetelet found for 63 male children, and 56 female, newly born, the following quantities:

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BOYS. 5.1608232 lbs. Maximum 9.92466

The mean weight, without distinction of sex, is 6.7377414 lbs. avoird. It has been found at Paris on 20,000 observations 6-74656332 lbs. avoird.

M. Quetelet has made similar inquiries concerning children from 4 to

STATURE.

1·62732 imperial feet.
1.58467

GIRLS.

2.4701376 lbs.
9.936329

12 years of age, in the schools of Brussels and in the orphan hospital-concerning young people in the colleges and in the medical school-finally, concerning old men in the magnificent hospice which has been constructed in the same

* A pamphlet in 4to, pp. 43. Brussels. 1833. Translated by the Rev. W. Ettershank.

THE STATURE AND WEIGHT OF MAN AT DIFFERENT AGES.

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a little more among individuals in easy circumstances, than in the indigent population who have recourse to hospices, hospitals, and gratuitous schools. The following table, which we may consider as exact for the whole population of Brussels, and which, for want of a table of this sort, calculated for other countries, may serve, at least, as an approximation for the Caucasian race, and in a temperate climate:

A Scale of the Development of Stature and Weight.

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