their houses are kept, every part of which affords proper materials for the production and detention of pestilential effluvia, and their igno rance of the importance of pure atmospherical air to animal life, and the consequent necessity of daily ventilating their apartments. It is also owing in a great measure to the custom of persons crowding into the chambers of those who are labouring under such infectious diseases, and thereby not only increasing the strength of the infectious virus, but absorbing a portion of it in their own bodies, to spread its baleful influence in a wider circle. Such a conduct frequently proceeds from a want of conviction of the infectious nature of such disorders, and from ignorance of the rapid manner in which they are sometimes communicated from one to another, as well as from that obstinacy and from those inveterate prejudices which are always the accompaniments of ignorance. Though the cow-por inoculation has been proved by experience to be an effectual preventive of that loathsome and often fatal disorder, the small-pox, yet numbers in the lower ranks of life cannot yet be persuaded to use this simple preventive, and will rather run the risk of experiencing all its disagreeable and dangerous effects both on their own persons and on those of their offspring. Their obstinate prejudices, in this and similar respects, are increased by their false views and reasonings respecting the doctrine of the divine decrees, and the providence of the Almighty. They imagine, that to induce one species of disease for the prevention of another is attempting to take the government of the world out of the hands of the Creator, and that no means of preventing disorders can be of any avail, if the Deity has otherwise decreed; not considering that the Almighty governs the world he has created by regular and invariable laws, and accomplishes his decrees through the intervention of those secondary causes, both natural and moral, which are continually operating in the physical and intellectual world. Were general knowledge more extensively diffused, and the minds of the multitude habituated to just principles and modes of reasoning, such fallacious views and opinions would be speedily dissipated, and consequently those physical evils and disorders which they produce would be in a great measure prevented.

Again, to ignorance we must likewise attribute, in a great measure, the pernicious effects of contaminated air in dwelling-houses. Pure air is essentially requisite to the health and vigour of the animal system as wholesome food and drink. When contaminated by stagnation, by breathing, by fires or candles, it operates as a slow poison, and gradually undermines the human constitution; yet nothing is less attended to in the economy of health by the great majority of mankind. Because air is an invisible

substance, and makes little impression on the organs of sense, they seem to act as if it had no existence. Hence we find, that no attention is paid by the lower orders of society to the proper ventilation of their apartments. In some cases, the windows of their houses are so fixed in the walls as to be incapable of being opened; and in other cases, where the windows are moveable, they are seldom opened, except by accident, for weeks and months together; and were it not that a door and a chimney are to be found in every habitable apartment, the air would be rendered in many instances absolutely unfit for respiration. Crowds of tailors, weavers, shoemakers, and other mechanics, employed in sedentary occupations, are frequently pent up in close, and sometimes damp apart ments, from morning till evening, without ever thinking of opening their windows for a single half hour for the admission of fresh air; and consequently, are continually breathing an atmosphere highly impregnated with the noxious gas emitted from the lungs, and the effluvia perspired from their bodies, which is most sensibly felt by its hot suffocating smell, when a person from the open air enters into such apartments. The sallow complexion of such persons plainly indicates the enervating effects produced by the air they breathe; and although its pernicious effects may not be sensibly felt, it gradually preys upon their constitutions, and often pro duces incurable asthmas, fevers, consumptions, and other dangerous disorders, which are frequently imputed to other causes. Nothing is more easy than to open the windows of an apartment, and other apertures that communicate with the external air, at meal hours, when the room is empty, in order to expel the conta minated air, and admit the pure vital fluid. No me dicine or restorative is cheaper or of more importance to health and vigour than pure atmos pherical air; yet, because it costs nothing, it is little regarded. Hints and admonitions in reference to this point are seldom attended to; for ignorance is always proud and obstinate, and the inconveniences supposed, in certain cases, to flow from the practice of ventilating particular apartments are seldom attempted to be remedied. It is, therefore, presumed, that were a knowledge of the nature of the atmosphere, of the ingredients that enter into its composition, of its indispensable necessity for the support and invigoration of animal life, of the circumstances by which it is deteriorated, and of the baneful effects which are produced by its contamination, more widely diffused, its use and importance would be more duly appreciated, and the disorders which flow from the circumstances now stated effectually prevented.*

ner, the danger arising from the want of a free cig The following fact shows, in an impressive manculation and frequent change of air. In the lying

extinguished before it reaches the bottom, it would be attended with imminent danger to venture down till the foul air be expelled. The noxious air may be destroyed by throwing down a quantity of quick lime, and gradually sprinkling it with water; for as the lime slakes it will absorb the mephitic air, and a person may afterwards descend in safety. Where lime is not at hand, a bush, or such like bulky substance, may be let down and drawn up several times; or some buckets of water may be thrown into it, till the air be so purified, that a lighted taper will continue to burn at the bottom. These precautionary hints will apply to all the other cases referred to, where this species of gas may happen to exist. To which I may also add, as another hint, that in every situation where fixed air is supposed to exist, it is more dangerous to sit or to lie down, in such places, than to stand erect; for, as this gas is the heaviest of all the gases, it occupies the lowest place; and therefore, a person lying on the ground may be suffocated by it, while another standing at his side would feel no injury, his mouth being raised above the stratum of the noxious fluid.*-I shall only remark farther on this head, that several disorders have been contracted by persons sleeping under the branches of trees in the nighttime, and in apartments where great quantities of fruit, or other vegetable matter, are kept, from ignorance of the fact, that during the night, the leaves of trees, and all vegetable matter perspire a deleterious air, which, when it has accumulated to a certain degree, may induce a variety of serious complaints, and sometimes prove fatal.

The disasters which have happened in coal mines, and other subterraneous apartments, form another class of accidents, many of which have been the effects of ignorance. Of late years an immense number of men, boys, and horses, has been destroyed by the explosion of inflammable air in the coal mines in this country, particularly in the north of England, where the most affecting and tragical scenes have been presented to view. On the forenoon of Monday, 25th May, 1812, a dreadful accident took place at Felling, near Gateshead, in the mine belong ing to C. T. Branding, Esq. When nearly the whole of the workmen were below,-the second set having gone down before the first had come up,-a double blast of hydrogen gas took place,

The grotto del Cani, a small cavern in Italy, about four leagues from Naples, contains a stratum of carbonic acid gas. It has been a common prac. tice to drive dogs into the cavern, where they suffer a temporary death, for the entertainment of strangers. But a man enters with perfect safety, and feels no particular inconvenience by standing in it, because his mouth is considerably above the surface of the stratum of deleterious air; but were he to He down he would be instantly suffocated. The same precaution may also be useful in walking through certain caverns in our own country.

and set the mine on fire, forcing up an immense volume of smoke, which darkened the air to a considerable distance, and scattered an immense quantity of small coal from the upcast shaft. In this calamity ninety-three men and boys perished. The mine was obliged to be closed up on the following Saturday, in order to extinguish the fire, which put an end to all hopes of saving any of the sufferers. On the 6th October, in the same year, and in the same county, (Durham,) a coal-pit, at Shiney Row, suddenly took fire, by explosion of the inflammable air; in consequence of which seven persons were severely scorched. And on the Saturday following, (October 10th,) the Harrington Mill pit, distant from the other about two or three hundred yards, also took fire; by which four men and nineteen boys were killed on the spot, and many people severely wounded and burned, and two boys were missing. This dreadful catastrophe was likewise occasioned by the explosion of firedamp. The above are only two or three examples of a variety of similar accidents which have happened, of late years, in the coal districts in the northern part of our island. That all such accidents could have been prevented by means of the knowledge we have hitherto acquired, would perhaps be too presumptuous to affirm; but that a great proportion of them were the effects of ignorance on the part of the miners, and might have been prevented by a general knowledge of the nature and causes of such explosions, and by taking proper precau tionary measures, there is every reason to believe. That this is not a mere random assertion, will appear from the following extract from the Monthly Magazine for February 1814, p. 80:-" Mr. Bakewell, in his late lectures at Leeds, stated the following circumstance, which strongly evinces the benefits which arise from educating the working classes-that, in the coal districts of Northumberland and Durham, accidents are constantly taking place from explosions in the mines; so that not less than six hundred persons have been destroyed in the last two years. But, in one of the mines which was frequently subject to explosion, not an accident of any consequence had taken place for the last twelve years; the proprietors, besides other precautions, having for a considerable time past educated the children of the miners at their own expense, and given them proper information respecting the nature of the danger to be avoided.”‡

See Monthly Magazine, vol. xxxiii. p. 580, and vol. xxxiv. p. 462.

This section of the present work was written in 1816, and the facts referred to in it happened within three or four years of that date. Since that period Sir Humphrey Davy's ingenious contrivance, called the safety lamp, has been invented, by means of which, we have every reason to believe, many acci dents in coal mines have been prevented, and many lives preserved from destruction. The peculiar property of this lamp is, that the miner may move about

Were the working miners carefully instructed in the nature and composition of the atmosphere, and its chymical properties, and particularly in the nature and composition of the different gases,-were such instructions illustrated by a judicious selection of chymical experiments, and were the proper practical hints and precautions deduced and clearly exhibited, there cannot be the least doubt that it would be attended with numerous beneficial results. When a person is ignorant of the noxious principles that may be secretly operating within the sphere of his labours, he will frequently rush heedlessly within the limits of danger; whereas, a man who is thoroughly acquainted with all the variety of causes which may possibly be in action around him, will proceed in every step with judgment and caution, and, where danger is apparent, will hasten his retreat to a place of safety.

The injuries which are produced by the stroke of lightning form another class of accidents which are frequently owing to ignorance. It is still to be regretted, that, notwithstanding the discoveries of modern philosophy, respecting the electric fluid and the laws of its operation, no thunderguard has yet been invented, which, in all situations, whether in the house, in the street, in the open field, in a carriage, or on horseback, shall serve as a complete protection from the ravages of lightning. Till some contrivance of this kind be effected, it is probable that the human race will still be occasionally subjected to accidents from electrical storms. Such accidents are more numerous and fatal, even in our temperate climate, than is generally

with it, and even work by its light in the midst of those explosive mixtures which have so often proved fatal when entered with a common lamp or a candle. It transmits its light, and is fed with air, through a cylinder of copper wire-gauze. The apertures in the gauze are about one-twentieth or onetwenty-fifth of an inch square, and the thickness of the wire from one-fortieth to one-sixtieth of an inch diameter. The parts of the lamp are:-1. The brass cistern which contains the oil. 2. The rim in which the wire-gauze cover is fixed, and which is fastened to the cistern by a moveable screw. 3. An aperture for supplying oil, fitted with a screw or cork, and a central aperture for the wick. 4. The wire-gauze cylinder, which consists of at least 623 apertures to the square inch. 5. The second top, three-fourths of an inch above the first, surmounted by a brass or copper plate, to which the ring of suspension is fixed. 6. Four or six thick vertical wires, joining the cistern below with the top plate, and serving as protecting pillars round the cage.

When the wire-gauze safety lamp is lighted and introduced into an atmosphere gradually mixed with fire-damp, the first effect of the fire-damp is to increase the length and size of the flame. When the inflammable gas forms one-twelfth of the volume of the air, the cylinder becomes filled with a feeble blue flame, but the flame of the wick appears burning brightly within the blue flame, and the light of the wick increases, till the fire-damp increases to one-fifth, when it is lost in the flame of the firedamp, which fills the cylinder with a pretty strong light. As long as any explosive mixture of gas exists in contact with the lamp, so long will it give its

imagined. From an induction of a variety of facts of this kind, as stated in the public papers and other periodical works, in the year 1811, the author ascertained that more than twenty persons were killed by lightning, or at the rate of a thousand persons every fifty years, during the summer months of that year, within the limits of our island; besides the violent shocks experienced by others, which did not immediately prove fatal, and the damage occasioned to

light, and when it is extinguished, which happens of the atmosphere, the air is no longer proper for when the foul air constitutes one-third of the volume respiration, for though animal life will continue where flame is extinguished, yet it is always with suffering.

DAVY'S SAFETY LAMP.

The following are the principal parts of the safety lamp:-F is the lamp throwing up a brilliant flame. C is the reservoir, supplied with oil by the tube M. EE is a frame of thick wire to protect the wire gauze, A A A A, which has a double top G H. The frame has a ring P attached to it for the convenience. of carrying it. The wire-gauze is well fastened to the rim B.

Notwithstanding the utility of this invention, such is the carelessness and apathy of the working miners, that they either neglect to use their safety lamps, or to attend to the means requisite to keep them in order,-which carelessness and apathy are the effects of that gross ignorance into which so many of them are sunk. Hence we find, that seldom a year passes in which we do not hear of destructive explosions happening in our coal mines, particularly in England.

sheep and cattle, and to public and private edifices; and it is worthy of notice, that most of the individuals who were killed by the lightning had either taken shelter under trees, or were in situations adjacent to bells or bell-wires. The experience of succeeding years proves that a similar number of disasters of this kind aunually take place. It is, however, more than probable, that at least half the number of accidents arising from the same cause might have been averted, had the nature of lightning, and the laws which regulate its movements, been, generally known. Seldom a year passes but we are inforined by the public prints of some person or other having been killed by lightning, when taking shelter under a large tree,-of whole families have been struck down when crowding around a fire-place, during a thunder-storm, of one person having been struck when standing beside a bell-wire, and another while standing under a bell connected with the wire, or under a lustre hanging from the ceiling.

There can be little doubt, that a considerable number of such accidents would have been prevented, had the following facts respecting the nature of lightning been extensively known :That lightning is a fluid of the same nature, and is directed in its motions by the same laws which regulate the motions of the electric fluid in our common electrical machines ;-that it is attracted and conducted by trees, water, moisture, flame, and all kinds of metallic substances; -that it is most disposed to strike high and pointed objects; and that, therefore, it must be dangerous to remain connected with or in the immediate neighbourhood of such objects when thunder-cloud is passing near the earth.

Hence the following precautionary maxims have been deduced, by attending to which the personal accidents arising from thunder-storms might be in a great measure prevented. In the open air, during a storm, rivers, pools, and every mass of water, even the streamlets arising from a recent shower, should be avoided, because water being an excellent conductor, might determine the course of an electrical discharge towards a person in contact with it, or in its immediate neighbourhood. All high trees and similar elevated conductors should also be avoided, as they are in more danger of being struck than objects on the ground; and, therefore, a person in contact with them exposes himself to imminent danger, should the course of the lightning lie in that direction. But, to take our station at the distance of thirty or forty paces from such objects, or, at such a distance as may prevent us from being injured by the splinters of wood, should the tree be struck, is more secure than even in the midst of an open plain. Persons in a house not provided with thunder-rods, should avoid sitting near a chimney or fire-place, whether there be a fire in the

grate or not. For when there is a fire in the grate, the fire contains the following conduetors,-flame, smoke, rarefied air, and soot. Even when there is no fire, the soot with which the flue is lined is a conductor; and from the superior height of the chimney-shaft above every other part of the building, it is more liable than any other part of the house to be struck with lightning. In a house, too, gilt mirrors or picture-frames, lustres or burning candles, bell-wires, and all metallic substances, should be carefully avoided, as they afford so many points of attraction, which might determine the course of an electric discharge. The safest position is in the middle of the room, if not near a lustre, a bell, or any thing hanging from the ceiling; and if we place the chair on which we sit on a bed or mattress, almost every possible danger may be avoided * Such are a few maxims easy to be recollected and put in practice, by attending to which, not a few accidents from electrical explosions might be averted.

In the next place, various accidents have happened from ignorance of certain plain mechanical principles. For example, serious accidents have sometimes occurred from the want of acquaintance with the laws of motion. Persons have heedlessly jumped out of moving vehicles, and got their legs and arms sprained or dislocated, and from one boat to another when both were in rapid motion, and run the risk of being either bruised, drenched, or drowned. But had the effects of compound motion been generally known and attended to, in all those cases where it occurs, it would have prevented many of those accidents which have happened from persons rashly jumping out of carriages when in rapid motion, or attempting to jump from the top of a moving cylinder, in which cases they are always precipitated with violence in a direction different from what they expected, from the obvious effects of a combination of forces. Boats and carriages have been sometimes overset by persons rising hastily when they were in danger of such accidents,-from ignorance of the principle, that the centre of gravity of the moving vehicle, by such a practice, is raised so as to endanger the line of direction being thrown beyond the base, when the vehicle must, of course, be overturned; whereas, had they clapped down to the bottom, they would have brought down the line of direction, and consequently the centre of gravity, farther within the base, so as to have prevented the accident and secured their safety.

It has been generally thought that the cellar is the most secure situation during a thunder-storm; but this is true only in certain cases. When the lightning proceeds from the clouds, it is unquestionahly the most secure position; but in the case of a returning stroke, or when the lightning proceeds from the earth, it is less secure than the higher parts of the building.