inches of water, weighing eleven ounces troy weight for as one cubic inch of water when decomposed, yields 1,325 cubic inches of hydrogen, weighing grs. 28.06 224.46 252.52 we at once find, as 1,987 cubic inches of these mixed gases give one cubic inch of water; 41,472 cubic inches of the gases mixed in the same proportions, (being the hydrogen and oxygen consumed, per hour,) will give 20-88 cubic inches of water, which at 252 grains per inch, makes the weight above stated. The quantity of carbonic acid produced, is exactly equal in bulk to the total quantity of the carbureted hydrogen used; and therefore, supposing such a stove as above described to burn fifteen hours a day, there will be formed 13 pounds 9 ounces, or nearly a gallon and a quarter of water; and 207,360 cubic inches of carbonic acid gas, per diem. Unless the quantity of pure atmospheric air be such as to afford an ample supply of oxygen, a portion of the gaseous carbon will escape unburned, and will then be given off in the form of an impalpable powder, having the appearance of smoke on the ceiling and walls of the room, and will also be inhaled by the persons breathing this contaminated atmosphere, to the undoubted injury of their lungs. From what has previously been said about the quantity of moisture given off by the human body, we must at once see that from the great quantity of water formed by these stoves, and which is exhaled in the form of vapour, the atmosphere of any room where they are used, must be incapable of receiving the due quantity of moisture from the human body: in addition to which, from the large quantity of the deleterious gas, carbonic acid, which is formed, and from the immense consumption of oxygen by these stoves, the air is not able to afford a due portion of vitality to the human frame. Whatever be the end to which oxygen is applied in the animal economy, it is certain that it, in some way, goes to repair the waste of animal power, and there is a demand for an increased quantity when there is increased muscular exertion: hence the greater number of respirations, and the laborious breathing after running or other violent exercise, and the deep drawn sighs and forced inspirations when we feel extraordinary lassitude, by all which means we obtain larger quantities of oxygen; and when we breathe an atmosphere which contains too small a per centage of this vital fluid, we feel great languor and depression. If each one of these effects be injurious by itself, they must, in cumulo, be highly detrimental, and the evils which arise from the use of hot-air stoves and flues, are generally much increased by imperfect ventilation. (To be continued.) FALL OF TEMPERATURE IN ASCENDING THE Ir has long been known to philosophers and men of science, that the higher we ascend in the atmosphere the colder it is. The scientific solution of the problem of the rate, however, at which the temperature sinks with regard to the ascent, is one of great difficulty, and has very much embarrassed mathematicians. To this moment it is a subject of dispute; some imagining one law of decrease, some another. Mathematicians of the highest order, though they have bent their utmost attention to it, have not been able to deduce, even from experiment, the true rate of decrease. Some years ago the subject was taken up by the editor of this magazine, as forming part of a work he was then engaged in preparing for publication; and from theory alone, with barely the specific gravities of air and mercury, unaided by any experiment, he was enabled to solve the problem-the most difficult he had then encountered in the whole range of the physical sciences. It appears from this solution, that the temperature of our atmosphere, supposed dry and in its mean state, reckoned on our thermometers, decreases uniformly at the rate of 0.92Fahr., or 0.511 Centigrade for every hundred yards of altitude. Following this law, the subsequent table of depressions, extracted from a much more extensive table computed for the work before alluded to, will easily enable the reader to determine the average decrease of temperature at any altitude : : In the subjoined table I have compared the theory with the collection of celebrated experiments by M. Ramond; and the insignificance of the mean error in 42 experiments, made under nearly every variety of clime and circumstances, from altitudes of 300 to 7630 yards, is a proof of the accuracy of the law, and consequently of the confidence which may be placed in the above table. It will here be seen that the rate of decrease is very small, being somewhat less than 16° Fahr. for every mile. We may, therefore, suppose that in railways it will be a matter of trifling consequence. Possibly it may; but if we consider that a single degree will be sufficient to change a damp-rail at the temperature of about 32° Fahr., into one glazed with ice, on which a train could not move, it will evidently be a matter of some consequence in the laying down of these expensive lines to avoid every chance of obstacle or injury to the free working of them, by keeping their summits as low as possible, so as to be the least affected by temperature. Our tunnel advocates will very likely lay hold of this circumstance to argue in favour of tunnels, in the same way as some of them did some time ago of my observations on the effect of dews. But I would recommend them to be a little cautious. It is quite needful, when one enters the field of philosophical induction, to take into consideration, not the bearings of one subject only, but of all which are any how related to it. Hereafter I may enter more fully into this matter, and I shall then have to shew that deep cuttings will possess nearly all the advantages, and be free from all the disadvantages of tunnels. EDITOR. CONDENSED AIR ENGINES FOR RAILWAYS, &c. OUR ingenious townsman Mr. Alexander M'Grew, has invented a mode of obtaining and applying power for the purposes of propelling ears upon railroads, and boats upon canals and rivers, which we deem of the utmost importance; and which, in our opinion, must, sooner or later, in a great measure, supersede the use of steam. The power is derived from condensed air, obtained and applied in a manner so cheap and simple, as to render the expense a matter of little or no consequence. We have witnessed, by the politeness of Mr. M'Grew, the practical operation of this invention, and are fully convinced of its entire success. Mr. M'Grew has exhibited his plan and practical models to several of the most distinguished engineers in the United States, all of whom concur in deeming the invention of the highest possible importance, and declare their belief that it will almost entirely supersede the use of steam. The inventor has taken out a patent. CINCINNATI WHIG. [We hope Mr. M'Grew will not deceive himself. If he succeed in this, it will be much more than we expect].-ED. EXACT CALCULATION OF THE VELOCITY OF SOUND. BY THE EDItor. [This Paper was read at a Meeting of the British Scientific Association at Oxford, and afterwards at the Bristol Literary and Philosophical Institution; but the Author has declined repeated solicitations to publish it until now.] EXCEPT the quadrature of the circle and the solution of the irreducible case, no problem, at least of modern times, has obtained more celebrity than that which requires from theory alone, the exact determination of the velocity of sound. The obstinacy with which this problem has resisted the abilities of Newton, Euler, Lagrange, Laplace, Poisson, Ivory, &c. is sufficient to convince any one that something must be amiss in the principles assumed; for it would be difficult to believe that any analytical defect in the process of solution could escape the sagacity of such men. It is not my intention to occupy the time of the Association with discussing the methods pursued by the above distinguished philosophers; it is enough to know, notwithstanding their utmost efforts and the new hypothesis of Laplace, aided by the best of experiments, that the result of theory still differs from the quantity observed, considerably too much to be attributed to the errors of observation. If, therefore, any other and more simple view than that commonly received of the constitution of aeriform bodies can be taken, perfectly consistent with other phenomena, from which by a mere elementary process the true velocity of sound can be elicited, I trust it will not be unacceptable; particularly when the Association is informed, that it is only one out of a great variety of phenomena to which the same principles apply with the greatest facility and accuracy. Before another meeting of the Association takes place, I hope I shall have been enabled to submit to the scientific world a part at least of my labours on these subjects in a connected form, and rigidly tested by experiments.* Newton, it is well known, proposed to philosophers to inquire whether our air, and all such bodies, do not consist of particles endued with a property of mutual repulsion, varying in force inversely as the distance, and always reaching the nearest particles, however much the air is expanded, and not extending beyond them, or at least not to the next, however much the air is compressed. It is on this hypothesis, that philosophers have hitherto endeavoured to * Ill health and other affairs prevented the publication. |