from me by a failure of every other method to obtain any satisfactory explana tion, and did not proceed from a spirit of resentment. To the matter of his communication in your Magazine for January last, so far as I can understand it, it would be easy to reply; and to show that the facts of the case are but partially stated. But this is conceived to be unnecessary; for any one who examines it, will perceive that it is but an unwilling acknowledgment of most of the errors I had pointed out. As to the "Chronological Cycles," &c. a London copy has been examined since my first statement, and these were found to be correct in it, or as I had put them down. The manner of Mr. Blunt's communication is such as not to deserve a reply. By writing with so much warmth, he defeats his own object. As to my statements, I shall only say, that what is written, is written; and though I would make no pretensions to accuracy, and wish not to engage in any public dispute, yet, whenever I may chance to notice any errors of magnitude in a work of such vital importance as the Nautical Almanac, I shall consider myself bound to offer them for publication, whether they be made by A, B, or C. For 1819. Page 4, Mercury's Helio. Lat. 16th day, for 6° 22', read 6° 42'. Page 16, Mercury's Helio. Lat. 10th day, for 3° 40′, read 1° 40'. Venus' Geo. Lat. 25th day, for 4° 35', read 3o 35'. Saturn's Geo. Long. 1st day, for 11s 6° 18', read 11s 16° 18'. Page 19, Moon's Parallax, 6th day, noon, for 54' 2", read 54' 0". ·Prop. Log. 6th day, noon, for 5226, read 5229. Page 23, Distance Moon and Regulus, 14th day, III hour, for 45° 0′ 56′′, read 48° 0′ 56′′. Distance Moon and Spica, m, 17th day, midn. for 59° 0′ 13", read 39° 0′ 13". Page 25, Conj. Moon and Mercu. for 25d. 7h. 29m. read 26d. 3h. 56m. Page 28, Mercury's Declinat. 28th day, for 4° 8', read 7° 8'. Page 29, Moon's Lat. 10th day, midn, for 30 9' 7", read 3° 29' 7". Page 31, Moon's Semid. 9th day, midn. for 14' 0", read 15' 0". Moon's Parallax, 11th day, noon, for 55′ 4′′, read 55′ 41′′. Moon's Parallax, 25th day, noon, for 59′ 43′′, read 58′ 43′′. Page 52, for Inf. * 8 2d. 16h. read Inf. ơ, 2d. 16h. Page 53, Moon's Lat. 1st day, midn. for 5° 3′ 28", read 5° 3′ 28′′ N. Page 58, Dist. Moon and Sun, 1st day, 9th hour, for 82° 32′ 46′′, read 83° 32′ 46′′. This error is also contained on the 6th page of the Almanac, previous to the calculations, as an erratum to the London copy. The minutes in that copy appear to have been corrected; but the degrees are put down one less than the true number. Page 65, Moon's Lat. 1st day, midn. for 2° 29' 36", read 2° 29′ 36′′ N. Page 76, for 6 1d. 34h. read Sup. ♂ id. 3th. Mercury's Geo. Lat. 25th day, for 1° 51', read 0° 51'. . Mercury's Geo. Lat. 28th day, for 1° 27', read 0° 27'. Mercury's Geo. Lat. 31st day, for 1° 1', read 0° 1′. Page 77, Moon's Lat. 1st day, midn. for 0° 38′ 41′′, read 0° 38′ 41′′ S. Page 89, Moon's Lat. 1st day, midn. for 4° 24' 11", read 4° 24′ 11′′ S. Moon's Lat. 30th day, midn. for 4° 10′ 41", read 5° 10′ 41′′. Page 100, for Inf. * 8 6d. 16h. read Inf. 66d. 16h. Page 133, for enters 24, read enters, or capricorn. Page 134, Sun's Declinat. for North, read South. Page 135, Sun's Semid. 1st day, for 16′ 52",4, read 16' 15",4. This error, also, may be found on the 8th page of the above mentioned errata. Page 136, for Inf. 22d. 18h. read Inf. ₫ 22d. 18h. The two corrected times of the conjunctions of the moon and planets given above, against pages 25 and 37, were ob tained by the longitudes of the objects in the Almanac, and, therefore, may not be correct to the nearest minute; since the planet's longitudes in that work are put down only to minutes. Respectfully, yours, EDWARD HITCHCOCK. Deerfield, Mass. June 6, 1818. * Opposition. For the American Monthly Magazine. If J. G. the learned correspondent of the Magazine for May, will take the trouble to look into Lowth's Syntax, he will find the phraseology which he so justly censures, distinctly authorized. To the authority of Lowth is undoubtedly to be ascribed the prevalence of the error in question. This opinion of Lowth's has been often controverted:-by Campbell, in his "Philosophy of Rhetoric," book ii. ch. 4-by Crombie, in his "Treatise on the Etymology and Syntax of the English Language," Syntax, rule xv.-by Priestly, in his "English Grammar, Notes and Observations, sect. ii.-by Murray, in his "English Grammar," Syntax, rule x.-by Webster, in his "Philosophical and Praetical Grammar," Syntax, rule xxv.-&c. &c. How, then, J. G. could be understood in saying that this uncouth form of speech has "lately" crept into the language, and that it has hitherto escaped all public animadversion," is not so clear. P. Q. 32 Although the inaccurate phraseology animadverted upon by J. G. was long ago employed, it was not sanctioned by the practice of eminent writers; and it has not been, until lately, frequently to be met with. The very frequent and growing use of it now-a-days, called forth the strictures of J. G.; and although it has been noticed by the best grammatical treatises, yet it has not, we believe, been made the subject of stricture in the popular periodicals of the day. For the American Monthly Magazine. MESSRS. EDITORS, There is a circumstance, of which I have taken notice, during the continuance of very hard frosts, which appears novel to most people in this country to whom I have mentioned it; and it has sometimes subjected me to the alternative of stating facts in a very positive manner, or of running the risk of being disbelieved. As I do not recollect to have seen it mentioned in any work I have read, I should be gratified to have you take notice of it in your very valuable Magazine. The circumstance alluded to is-that the best gun locks will not fire gun-powder during intensely cold weather, or when the Mercury stands 20° or more below 0, if exposed fairly to that temperature. On the day, known all over this country as the cold Friday, in the year 1809 or 10, a gentleman, one of the N. W. company, observed to me, as he was going to the cupola of the Cathedral with his thermometer, that my gun (which was one of Fletcher's patent breeches, with a fine agate flint) would not fire gunpowder; and on my expressing some doubt on that point, he followed by saying, that he had hunted many days in the north when he could not get his gun off from the effects of cold, to his great mortification, when game was plenty. We immediately prepared for the experiment, and left the gun for twenty minutes or more in the most exposed place we could readily come at, when to my very great surprise, on repeated trials, the flint slid as ineffectually over the steel as if it had been wood, and it did not fire until it had been in a warm room for more than 20 seconds. This experiment was tried at Quebec, in Lower Canada, where I resided at that. time.-On the cold Friday of last year, and on the cold Wednesday of the present past winter, I tried it with the same effect, only in these cases the gun was not as good an article as in the former experiment, yet it almost immediately flashed on being brought into a room with a stove. It Every one who saw the experiment tried, immediately formed some theory to account for it-which were so contradictory and unsatisfactory as to leave me in the dark as to the real cause. is well known that all metals when exposed to colds grow shorter, and of course the springs were stronger than when in a more warm and expanded state; and it was a fair conclusion that a lock ought to give more fire cold, than when warm, or in the ordinary temperature of the atmosphere, were the facts not in direct opposition to the theory. It was argued that the oil used to lubricate the lock became so congealed, as to create so great friotion that the springs could not drive the hammer open with sufficient force to elicit sparks-again, that the spark was extinguished by the intense cold air before it reached the powder-or, that the steel was so full of frost as to deaden the spark on the principle of snow or water's extinguishing fire. The two last, I hold as preposterous and false reasoning.-I think I cannot have been deceived by any fortuitous circumstances in my own experiments, or in the very respectable authority from which I first learned the existence of the fact. If you should think the subject of sufficient importance to give it publicity, or any of your correspondents to speculate on it, I should feel myself highly gratified. A. L. Your most obed'nt serv't, The following article has been called forth by the appearance of Mr. Busby's "Essay on the Propulsion of Navigable Bodies," and the account of his discoveries and inventions, published in our last number. Mr. Busby and Mr. Staples are, we believe, total strangers to each other; it has, however, been supposed, by the friends of the latter, that the modes of propulsion suggested by these gentlemen interfere. We, nevertheless, submit that the two plans differ, in essential points; but, recommending an attentive consideration of their respective merits, we leave our readers to determine which should obtain the preference. AIR BOAT. MESSRS. EDITORS, As one of the objects of your useful Magazine is to disseminate the knowledge of new inventions and improvements,-I avail myself of that medium to lay before the public the result of a course of experiments in mechanical science, and particularly as applied to navigation. A variety of untoward circumstances have combined to prevent an earlier developement of all the facts now deduced; but the time seems to have arrived when I should no longer remain silent.-In giving this to the public I do not arrogate to myself the discovery of any new principle in mechanical or chemical philosophy, but I lay claim, with perfect confidence, to all the advantages that may arise from a new and practically useful application of long known principles. The science of mechanics, very early engaged my attention; and I happened to be in England at the time that Bolton and Watt had perfected the steam-engine, and was then indulged with an opportunity of witnessing its useful effects in their extensive manufactories. I saw the same engine afterwards tried by Mr. Fitch for propelling vessels on the Delaware, and by many others in different places, and lastly by Mr. Fulton, who, being satisfied with the engine, considered only the best method of applying its powers to navigation, although it is very apparent he did not select the most elegible appendages to give that engine all its adtages of propulsion. When the first boat was started from New-York, I took passage with a view to witness the experiment; and then noticed the great loss of power in the use of wheels-I saw that the paddles entered and left the water at an angle of about 45° and when entering, could only exert on its surface about half of the power with which they were moving, the other half being spent in efforts tending to elevate the boat, occasioned a reaction, which oppressed the machinery, and caused a constant vibration of the vessel-hence a loss of power by the increased friction, in addition to that sustained by the perpendicular action of the paddles, both in entering and leaving the water. But the leaving paddles has even a worse effect, by breaking the volume of water on which the pursuing paddle is required to act in its nearest approach to a horizontal line; and this is an objection that will apply to wheels of every description. Stimulated by a desire to correct these evils, I have, from that time, been occasionally engaged in a succession of experiments-one inducing another, one idea unfolding another in regular progression, until I have attained the climax of my wishes-an economical application of known principles to useful purposes. Prior to the period alluded to, I was engaged in experiments on the tide wheel, with a view to relieve them from the resistance of back water, and succeeded in the attempt, by using upright paddles; and when the objections to the common wheel, as applied to boats, were so evident, it appeared to me that the applica tion of what I term the improved wheel would be very useful. But the trouble and expense of its construction; the difficulty of repairing any injury, except by a skilful artist; and the extreme accuracy ne cessary in its structure to take off some of the immense friction inseparable from such a combination of parts, determined me to relinquish that, and substitute a solid wheel, somewhat similar to the one in common use, but with a less number of floats, to prevent as far as possible the breaking of the volume of water unneces sarily; and placed in an inclined instead of a verticle position, enclosed in a horizontal trunk open at each end. There were too objects expected from the use of the trunk-one to gain buoyancy by extending the surface and preventing, as far as possible, the unequal operation of the wheels, in rough water; the other, to confine the water about the wheel, and make it approximate as nearly as possible to a solid substance. I had no sooner cffected this, than my attention was called to examine a circular engine on a new construction, just then made known to me, being anxious to witness the result of experiments then going on in NewYork, because I had already been engaged for some time in similar trials; but when I found that steam was the only agent, and its reaction could not be overcome, I felt under no apprehensions as to an interference in my plans. My circular engine is, I believe, entirely free from the defects common to all others that I have any knowledge of, being a horizontal movement, and actuated by an elastic, or a non-elastic fluid, or both; and in the latter case the engine is occupied with hot water, which is interposed, because it lessens the necessity of tight packing, and does not diminish the operating force of the engine by any reaction, which cannot be so well prevented in the use of elastic fluids only. Such, however, were the prejudices against circular engines, occasioned by recent unsuccessful applications, that I judged it prudent to suspend the introduction until I could accompany it with other improvements connected with its operation. My attention was now turned to an article inserted in the newspapers from an English publication, stating that a gentleman had obtained a patent in London for the application of condensed air as a new power to propel vessels, by injecting it under the bottom, thus causing a reaction of the water in its escape to the surface, by expansion on a part of the bottom inclined for that purpose. This article was followed by two others, the one from Boston, and the other from Philadelphia, each claiming a priority of application. Similar matters had engaged my attention, but I went further than they did. They found that nothing was to be gained by this application of force, sufficient to compensate for the loss of power in obtaining it—in my application I used heat as an auxiliary, having previously discovered that air will expand in proportion to its density with the same degree of heat. This matter will be more fully noticed when speaking of the engine and appendages asat present arranged. To obviate the difficulties attaching to all wheels as before noticed, I tried the effects of simple instruments, operating on the water under the stern of a vessel, on the principle of an oar, and found them preferable to the paddles or floats of a wheel; but their progress in the water not being in the line of the boat's direction, I constructed a pair of parallel oars -these operated admirably, with the exception of a slight resistance on entering and leaving the water. Although it was very evident, that vast power was to be obtained by condensed air rarified; yet, separate from other objections, the use of it, as before noticed, was not desirable on the score of economy. Hence I was led to think of a dif ferent application under the vessel, and with this view I found it necessary to have its bottom flat, with the part near the stern inclined upwards. I then contrived a set of plungers, which were to operate in trunks passing through the bottom of the vessel near the sides, on an angle of about 45°, rising in the vessel about three feet above the bottom, and connected with similar trunks under the bottom, extending from one extremity of the vessel to the other, and also attached to its inclined part, rising to the surface of the water under the stern of the vessel. having a portion of that inclined part, near the extremity of the trunk, removed for the purpose of producing a reaction of the water on it. The piston rods of these plungers are connected with the cranks on the main shaft in pairs, the cranks being so arranged as to distribute the power in an equable manner. There are three pairs-the two outside plungers moving together, the others succeeding in the same order. The surface of the plungers, when in contact with the water, is perpendicular, and if necessary may occupy the whole breadth of the vessel-hence the surfaces of the plungers may be made to bear on a section or column of water vastly greater than can conveniently be allowed for the action of any wheel or oar. Although these plungers will be more firmly resisted by the water than the oars or paddles of wheels possibly can be, yet by the yielding of the water, some little suspension of power will ensue; but by its immediate reaction on the inclined part of the bottom, it will be restored. Having now satisfied myself with arranging the instruments to operate on the water, I resumed my experiments on air for the purpose of ascertaining the best methods of combining in practice its greatest economy with convenience; and considered, as connected with its application, the properties of heat, and the capacities of bodies for retaining heat-and my conclusions are drawn from the following statement of experimental facts:- Of all the compressible fluids, air is the most familiar-hence it will not be neces sary to give an elementary account of its distinguishing properties, further than is requisite to elucidate the theory I am going to advance. It is a well known fact that air is a compressible and dilatable body-that it is always in a state of compression-that it is an elastic fluid whose density is always proportionable to the compressing force that its elasticity is proportionate to its density, and that it will expand in proportion to its density; but it is not so well known that this expansion will be effected by the same degree of heat. The result of experiment had assured me of this fact, when I noticed in the Encylopedia Brittanica that AMONTON had expressed the same idea. It has been found by many experiments that air is of different constitutions-below it is warm, loaded with vapour, and very expansible; above it is cold, much drier, and less expansible, both by its dry ness and its rarity-moist air expands most by heat-rare air expands less than what is drier. Rarified air differs in nothing from common air, except that it is lighter, and contains more heat. Condensed air is heavier than common air, and contains less heat. The elasticity of air is greatly affected by heat, and the change by increase of temperature is different, according to its density or compression. In common with water and other fluids, air possesses gravity; and consequently will perform every thing in that way which water can do, making allowance for the difference between the specific gravities of each-air being 840 times lighter than water. There is another property which it has in common with steam or vapour: this is called its elasticity, by which, like a spring, it allows itself to be compressed into smaller bulk, and then returns again to its original size, upon removing the pressure. It has been so compressed as to take up but the 1000th part of the space it occupied before, and of course its density in that state being one thousand times greater than the air we breathe. In every state of density it has been found to retain its perfect fluidity, transmitting all pressures which are applied to it with undiminished force. The dilation of air by its elastic force, is found to be very surprising; it has been brought to dilate into 13,679 times its space, and this altogether with out the help of fire; and this property of elasticity is as the density of the air. By means of a suitable condensor, which may be actuated by any eligible power, an uncommon quantity of air may be crowded into a given space, so that without impairing its spring, 1000 atmospheres, or 1000 times as much air as there was at the same time in the same place without the instrument, may, by means of it, be thrown into a suitable vessel denominated a " Receiver," and its egress prevented by valves suitably disposed. In order to condense air to a very great degree, it will be requisite to have the condensor of a small bore, because the pressure against every square inch is 15 pounds, and, therefore, against every circular inch about 12 pounds. If the condensor be one inch diameter when one atmosphere is injected, there will be a resistance of 12 pounds against the piston; and when ten atmospheres are injected, there will be a force of 120 to overcome; and as the facility of working will be inversely as the squares of the diameter of the condensor, it will be proper to have them of various sizes, and to begin with those of a larger diameter, which operate more quickly; and when the resistance against the piston is nearly equal to the force employed, to change the condensor for one of a smaller bore. We judge of the condensat en or compression of the air in the receiver by the number of strokes, and the proportion of the capacity of the condensor to the receiver. Suppose the first to be one-tenth of the last, then we know that after ten strokes, the quantity of air in the receiver is doubled, and, therefore, its density double, and so on after any number of strokes. When any great power is employed, the condensation may be pushed to a great length. By condensation the quantity of absolute or specific heat in air is lessened, being pressed out through the pores of the metal, by which means the air is rendered more dense, compact, and heavy, and its capacity for receiving heat is increased. By heat all bodies are expanded every way, and that in proportion to their bulk and the quantity of heat communicated to them. The expansion takes place not only by an addition of sensible heat, but likewise of that which is latent; an instance of this expansive power of latent heat is found in steam, which always occupies a much larger space than the substance from which it was produced. All the experiments hitherto made conspire to show that the capacity and consequently the specific heat, is greater in the vaporous, less in the fluid, and least in the solid state. Many experiments have been made to ascertain the capacities of bodies for containing heat, and also the quantity of absolute heat contained in different bodies the temperature, the capacity for containing heat, and the absolute heat contained, are distinguished as a source distinct from the subject upon which it operates. "When we speak," says Dr. Crawford," of the capacity, we mean a power inherent in the heated body; when we speak of the absolute heat, we mean an unknown principle which is retained in the body |