thrown. This abstraction of the heat from the smoke is effected in a variety of ways, but generally by a warmer placed in the fireplace of each room over that in which the fire is lighted. The heating may be carried to any extent, and is regulated by the turning of a cock or valve which governs the admission of the smoke into the apparatus. In addition to this saving, the inventor also produces more heat from a given quantity of fuel, for his stove is so contrived as to burn the smoke, that is, a large quantity of carbonaceous matter which usually rises with it, and much inflammable air which usually escapes unseen. 2. As to Ventilation.-The vitiated air rising from the lungs, or from candles, lamps, &c. in the room, immediately passes away through a circular opening in the ceiling, from which a pipe conveys it to a large common tube in the staircase, and this last rises through the roof like a chimney, and is crowned by a ventilator. Through it the air from the upper part of every room in the house is constantly passing away, and mixing with the atmospheric ocean above, ensuring thus the absolute purity of what remains. The advantages of these plans over common methods may be most conveniently enumerated as follows: : 1. With a View to Economy.-One fire answers the purpose of several, with a saving of fuel proportionate. There is not the trouble of lighting and attending to many fires, and of cleaning the stoves and fire-irons; so that in many houses a servant might be spared. In many houses fires are required to be lighted from time to time in every apartment to remove dampness, and this during summer as well as in the winter; and it is not uncommon even for families to submit to the inconvenience of migrating from room to room on this account, while the purpose is immediately answered in the new plan, by directing the kitchen smoke through the warming apparatus of any particular room. The original expense is little more than that of setting common stoves. 2. The danger of fires in houses is necessarily much diminished by it. 3. There never can be smoke in a house so warmed, nor the consequent expense of renewing so often the papering and painting on account of it. 4. If elegance be studied, the new plan is susceptible of as much embellishment as the old. As we have been universally accustomed in this country to see the fire which warms us, and to account it' company in the nights of winter; for those who might be unwilling to relinquish this enjoyment in their sitting rooms at least, the inventor has planned some elegant specimens of a combination of the stove and warmer. These possess nearly the full advantage of the new plan with what is very pleasing to many of the old. 5. Temperature or Climate.-In every part of a house so fitted up the impression must always be that it is summer. A delightful uniform warmth is felt on all sides, quite distinct from the partial and unequal heat of a fire. There can be no pernicious draughts of air, damps in bed-rooms, chills on coming into the staircase, or on moving from one room to another; and these are the causes of half the winter diseases of our climate. An invalid in a house so warmed and ventilated need scarcely regret the climate of Lisbon or Madeira. The new apparatus shuts up the chimney altogether, except the little tube of the stove where a stove is used. The importance of this effect in securing uniformity of temperature may need explanation to some. In our ordinary chimney there passes up not only the air which has fed the fire, and has been heated by it, but a much larger quantity which enters it between the bottom of the mantlepiece and the fire. It is this last abstraction which produces the powerful and dangerous draughts which we always feel tending towards the fireplace, and which causes the sudden fall of temperature in a room when the door is left open for a minute. There passes off too, unfortunately, only the lower stratum of air into which the chimney opens, while the heated air above remains untouched. A common chimney, therefore, in addition to the great draught produced by it, must necessarily maintain a heated and impure atmosphere above the level of the mantlepiece, surrounding the heads of the company, and being breathed by them; and below, a stratum of cold air moving towards the fire, pure indeed, but answering only the purpose of chilling dangerously our feet and nether bodies which are immersed in it. 6. The Purity of the Air.-Man's existence depends immediately upon the agency of the air, of which he consumes in breathing the vital principle. Deprive him of air but for a minute, and he becomes senseless, and dies. Confine him to a small quantity without change, and the same effect as certainly follows. Change the air in any known way, or his body in its disposition to be affected by it, and the most striking results follow. With all this before us, it is singular that many of the certain consequences of breathing vitiated air should so long have been attributed rather to other causes than to the real one. While we see gaol, ship, and hospital, fevers, arising as necessary consequences where many persons breathe together in confined places, we have often attributed to want of exercise only the consumptions, debility, paleness, and premature death, of persons of sedentary habits or employments. Persons who are much abroad in the open air, and those who are not, may in all cases by their appearance be very easily distinguished from each other; and it is only among the former that we meet with longevity and vigorous health. By the plan of ventilation now proposed, it is evident that the air in a small study, or bed-room can never cease to be as pure as under the open sky. The proposer of these improvements, the Marquis de Chabannes, has received a patent, which ensures him some advantage from their adoption. His name will suggest a reflection, which has already often been made, that England has not only the honour of making the most important discoveries herself, but it is to her also that in ventive genius of other nations often comes to receive its reward. This Gentleman found refuge here with a numerous and infant family from the storms of the Revolution. I understand that his own estimable character, and his very interesting family, have procured for him here the attachment of many of our countrymen ; and he clings to their friendship, and to English security, in preference to any thing which his former country now offers. If, besides informing the public on a subject very important to it, I by this little account also render a service to such a man, it will be an additional pleasure to me. In considering the progressive improvements which men have made, and which at the present day they are making more rapidly than ever, in the arts of life, it is impossible not to be forcibly struck by the contrast which occasionally appears between early attempts and subsequent perfection. With regard to the subject of the present paper, for instance: man, without shelter and protection, requires for his comfortable existence the warmth of countries on which the sun darts nearly perpendicular rays, still by progressive art he has contrived to make even the regions of the frozen pole afford him almost every enjoyment of which his existence is capable. It was near the equator that Omnipotent Benevolence placed the first inhabitants of the earth, when new-born reason had not yet learned to mould obedient nature to its purposes; but as the race multiplied and spread, shelter was to be sought against the chilling blasts which were now found threatening death to the tender organizations of warmer climes. Here man built his cabin, and shut out the storm; he lighted his fire, and the noise of the elements without made him but feel more sensibly his comfort and security within. His means are now so complete, that he produces at will the climate which pleases him, in whatever part of the world he be placed; and thus while all other animals, unless protected by him, must perish when removed from the zone in which they first appeared, he, the lord of all, has made the whole earth his comfortable home, and its varieties of climate but minister to his pleasures. I am, dear Sir, yours, &c. THE accompanying figure (Pl. XLIII. Fig. 2) of an air-tight lantern to be used in coal-mines is in principle and form unquestionably of my own original conception, invention, and construction, many months ago. Upon the production of Sir H. Davy's lantern it was sketched, a copy taken, and, together with the following observations, awaited the judgment of the public upon that invention, as it might be declared or expressed in one or other of our two philo sophical journals. In No. 36 of Thomson's Annals for Dec. 1815, a lantern constructed by Dr. Murray, of Edinburgh, upon the same principle as this, of supplying itself with air from the bottom of the mine, is announced as having been exhibited and put in a course of trial. Although before the 1st of December, therefore, I had never heard of, and have as yet never seen, any representation of Dr. M.'s lantern, yet to him, repeating without any malignity of imprecation, the prefixed motto, amended from the adage "pereant qui ante nos nostra discerint," I resign the honour of prior discovery, and, which is of more importance, of future practical appli cation. The figure of the lantern shows its use. It receives the supply of air with which it burns exclusively from the bottom of the pit, through the flexible tube of leather, covering a spiral wire, and terminated by the perforated globe of metal at its lower extremity, which may drag along the ground, whilst the miner carries the lantern, or lie stationary upon it, when the light is stationary. This invention was suggested by the following observations, which may not be undeserving of notice, although the lantern of Dr. M. precede in existence, and be preferred in use. Coal-mines are infested with two sorts of noxious airs, differing essentially from each other in all their properties. The one, called by the miners the choak-damp, the azote and carbonic acid gases of chemical philosophy, is heavier than atmospheric air; the other, called fire-damp by the miners, the carbureted hydrogen gas of chemists, is lighter than atmospheric air. Of course the places occupied by each are the bottom and the top, the floors and roofs, of mines. Of these gases the former become less and less noxious in proportion to their commixture with atmospheric air; the latter more and more dangerous, and liable to explosion, in proportion to the same commixture, in quantities limited to six parts and 12 parts of atmospheric air. No commixture of these different noxious gases will explode. These various properties of these gases indicate the modes to be pursued to discharge them from mines, and to destroy their noxious qualities. The light air can be, and is, fired with safety, and consumed as it issues from the crevices of the mine before it mixes itself with the atmospheric air in proportions capable of exploding. But beyond all question the best and most direct mode of getting rid of it is to conduct it with as little agitation as possible, and mixture with the air of the mine, along the roofs of the mine or channels of intersection cut therein, to which in the original workings of the mine, and at all times afterwards, a due degree of inclination should be given for the purpose, to conduct it to up-air shafts, at which it would regularly and safely be discharged. Wherever the workings of the mine by irregularity of rise or elevation of roof should render it impossible to form these channels of connexion with established air shafts, a new air shaft should be formed to command the upward air-drainage of the new workings. Might not this be effected, and the number of up-air shafts be considerably increased without exceptionally deforming the upper surface of the soil, by ascertaining above by trigonometrical calculation the point from which descending a new shaft might be established; and might not such shafts be formed by an improved process in boring and letting down iron pipes to preserve and to keep open the shaft? If, in boring, any considerable quantity of water should be pierced, more than can easily be disposed of (the great objection to air shafts), as the boring would be from the top of the surface, no harm would ensue, and the boring on that point might be abandoned. The heavy, or azotic and carbonic acid gases, can only be rendered innoxious by ventilation and mixture with atmospheric air introduced from above by currents established by mechanical means through shafts and channels passing to the very bottom of the mine, or by giving directions to the currents produced by various causes within the mine itself. These mechanical means of discharge are applicable to these gases as noxious to human life generally, and undoubtedly they are the great and direct means to be resorted to for these purposes. The insufficiency of these means always to discharge the light gas, its explosibility, the necessity of using fires to give light in the dark abysses of the earth, and the difficulty of ascertaining when and where the dangerous accumulations thereof exist, have rendered it a desirable thing to discover, if possible, any mechanical contrivance by which the benefit of light may be obtained without the danger of fire. Two of the plans recommended for the purpose will be considered that which in times past has been invented, and continues to be now used, of obtaining light by the collision of flint and steel; and that which in the present day has been proposed by Sir Humphry Davy, and is now before the public, of a closed lantern, the passage of air through which is duly regulated. The use of flint and steel does not seem to be sufficiently understood in its principles. That it is not secure against explosions is admitted; and I am inclined to think that the dependance upon, and safety expected from, its use, is in a great measure illusory. Whenever it has produced explosion, it is not doubted that the flame of a taper would have produced it. Would the flame of a taper produce it where the collision does not? I am inclined to think that the light in fire, for such it is, produced by these collisions, fails to fire air not explodible, and fails not to fire explodible air. If the collision of flint and steel be made in vacuo at the points of contact, and there only, light is exhibited; when the collision is made in atmospheric air, the abraded portions of steel fly off in a high state |