418 CHIMNEY SWEEPING-BORING. tures: the object of this is, that the force of the steam, by which the rocket is propelled, may be under control, and capable of regulation by the employment of metallic plugs of different fusibility. I am, Sir, R. LEWTHWAITE. P.S. The patentee states that this invention is applicable to the discharge of a great variety of projectiles, but, as the principle is the same in all, he has thought it necessary only to describe the mode of adapting it to the discharge of rockets. CHIMNEY SWEEPING. SIR,-The subject of Sweeping Chimneys without Boys, having been noticed in your valuable pages, perhaps you will give room to the following. Several years ago, when the Society was first established for superseding the use of boys, I travelled in a stage coach with a gentleman (whose name I have forgot, but he was a Captain in the Westmorland Militia, and resided at Haslemere, in Surrey), who gave me an account of a machine he had invented for sweeping chimneys without boys, which, he said, answered most completely. He stated, that chimneys in London were built pretty nearly of the same dimensions. He therefore provided four brushes, made of short strong hair, such as scrubbingbrushes, of the size of the four faces of the chimney. On the back of each of these brushes was fixed a spring. The four brushes were then fastened together, hair outwards; they were supposed to fit the chimney. To this machine was fixed a rope, which passed over an iron bar placed on or near the top of the flue, by means of which the brushes could be pulled up and down the chimney till it was cleaned. If there was any accidental obstruction in the chimney, or it was narrower in one place than another, the springs permitted the brushes to be compressed; and when it widened, the springs always kept the brushes close to the faces of the chimney. When the chimney was thus swept, the brushes were taken off, but the rope remained in the chimney; and, for security, he recommended a chain, of three or four feet long, to be put to each end of the rope. He presented a model of this machine to the Society, but it was rejected, because it did not work wholly from the bottom, which the Bishop of Durham, the Chairman, said was a sine qua non. The inventor was asked if he knew how many iron bars must be put upon chimneys in London? That alone, said the Bishop, is an objection to this plan. The Captain said, that he took back his model; but that he had constructed the machine, and used it in his own house with great success. I am, Sir, yours, &c. CUMBRIENSIS. BORING. SIR.-Northumberland is the land of holes, and we learn to bore here in our infancy. The machines described in the Mechanics' Magazine, invented by M. Monnom and J. M., would do well enough if the earth was made of "chalk or cheese," but, unfortunately, it is full of great stones; and in boring in mines (which is the ne plus ultra of the art) we have to pierce through numberless hard strata, some of them 20 feet thick, so hard, indeed, that the machines above-mentioned might be turned round until doomsday without drilling through them. Your Correspondents do not seem to understand how these hard materials are cut through. It cannot be done by turning the rods round and round, however great the weight that presses them down: they are armed with a chisel, and by being lifted up and let down in a quick alternate manner, their weight acts like a hammer upon it, and thus cuts the stone. Some beds are so exceedingly hard that they cannot be cut even in this manner, but the rods have to be driven by a hammer, which is a very tedious ON NAVAL IMPROVEMENT. operation, as their great length and weight blunt the force of every blow. In boring through whin, &c. at a great depth, two inches is sometimes a good day's work! Your ingenious Correspondents will see of what little importance a machine to turn the instrument round will be in a place like this. If they can discover a method to jolt or beat with the rods better than can be done by the hand, or how to make them, when long, drive as easily as when short, they will do a great service to the public. I wonder what kind of metal J. M. makes his augers of to bear two men turning with a cross-head" 15 or 20 feet long?" The augers here are frequently broken with a head not more than three feet long; and to break one in the hole is a great misfortune, as it seldom can be got out, and, of course, prevents the hole from being made any deeper. I remain, Sir, Newton, near Alnwick. The building of three experimental vessels for the improvement of naval architecture having excited much attention in the public mind, not only from the peculiarly interesting nature of the science under inquiry, but from the professional abilities of the different projectors, the individual success of each ship has been observed with an anxiety commensurate with the importance of the object in view. If, notwithstanding the skill of the constructors, neither of these men of war showed decided superiority in sailing, the failure must be attributed to our ignorance of the resistance bodies meet with when opposed to the impulse of water. Our knowledge of this branch of 419 physics is nearly as limited as our acquaintance with the laws which govern the motion of the fixed stars; but here the parallel must end: the accumulated industry of ages alone will probably detect the cause which produces change of place amongst these heavenly bodies, whereas the advancement of hydrodynamics is within the influence of the present generation. If strength, durability, and efficiency, be all that is required in our floating fortresses, these characteristics have already been combined by the talent of Sir Robert Seppings. It appears that much uncertainty existed in the sailing of the experimental vessels: sometimes one had the advantage, sometimes another; the distinction resting mainly on the quantity and stowage of the ballast, alterations in the masts, yards, &c. The requisiteness of these changes is a proof that the highest genius is incapable of correctly anticipating either the qualities or the sailing powers of a ship prior to her going to sea. One great point has been gained by building these vessels, in showing that the synthetical process is inadequate to obtain the end in view. Is it not similar to a chemist, who, desiring to analyse metals, of which some were known and others unknown, first mixed them altogether, and then, after great pains, labour, and expense, discovered the impossibility of arriving at any accurate conclusion in regard to their respective properties; whereas had he, in the first instance, separately examined each, the result would have proved less fatiguing, less costly, and more satisfactory? In all complex cases, scientific or mechanical, the most easy and natural way for well understanding the subject, is to resolve it into the component parts. In the construction of ships, the great and leading features are stability and fast sailing; the theory of the former is sufficiently known, but our acquaintance with the resistance of non-elastic fluids may be termed yet in its infancy. The ablest builder is at present ignorant of the curves best adapted for dividing the water; 420 ON NAVAL IMPROVEMENT., and working thus in the dark, it is no wonder that the aggregate of slow sailers so far exceeds those that are fast. The importance of discovering the curve of least resistance is not confined alone to vessels moved by the power of wind. Constructors of steam-boats are deeply interested in the fact. If a packet with an engine of forty-horse power be driven nine knots in an hour, it will require an effort of nearly sixty-one horses to increase the speed to ten. Could this additional mile be gained, by giving the hull a more advantageous form for cleaving the water, many substantial benefits would accrue. The original cost of the engine would be lowered from the inferior size required, expenditure in fuel and stowage would be saved, and less risk incurred of the melting of the grate bars. In short, from the waterman who plies upon the Thames to the captain commanding the largest ship in the British navy, all are interested in finding the solid of least resistance; the first by diminishing the labour of the oar, and the latter by out-sailing, coming up with, and capturing the enemy's ship. Ships have been aptly compared to bridges connecting the whole world together; a slow-sailing vessel, therefore, is a bridge longer than necessary. It is not improbable that the Carthaginian and Roman builders surpassed the moderns in the form they gave their men of war for cleav ing the water, because, being frequently impelled by oars, to lighten the fatigue of the rowers, must have been a matter of the greatest mo ment. It is highly gratifying to observe the pleasure that several of the nobility and gentry take in maritime concerns. The Royal Yacht Club, by building vessels, and bestowing introducing for trial new and expensive machinery, is capable of performing services which few individuals could undertake; and it is submitted for the consideration of the body, whether considerable improvement in the science of sailing might not result from the following experiments. In Lug sails are usually thought. preferable to others in turning to windward, and such as are taunt and narrow are deemed more effective than those that are low and square; but this phrase of taunt and narrow is extremely indefinite. In the first instance, it is proposed that a vessel, rigged as a lugger, shall sail with others, and most likely one amongst them will be found either a company-keeper, or whose rate is nearly on a par. the next place, let canvas be taken from the breadth of the sails and added to the hoist, and a second comparison made; thus subjecting the sails to repeated alterations and trials, until the maximum of the length to the breadth be obtained. This fact established, the next suggestion is, to convert the lugger into a cutter, observing the necessary precaution, that the mainsail, foresail, and jib, expose the same sürface to the action of the wind as the sails of the lugger. The third trial consists in changing the same vessel into a schooner, scrupulous regard being paid that the quantity of sail is equal in the three cases, and that no variation in the weight, quantity, or stowage of the ballast, be permitted either in the boat of comparison, or experimental vessel. Rigid adherence to these points is essential to the success of the experiments, inasmuch as it is the action of sails, and not the best trim of the hull, which forms the object of the present inquiry. A vessel of size is prizes on the best sailers, enjoy the for several reasons desira Size is patriotic and praiseworthy conscious ness, that money so expended encourages some of the most useful classes of society, and creates a spirit of emulation among the different branches of artificers connected with nautical affairs. This institution, by one' of 14 feet beam, and 37 on deck, might prove sufficiently large; but the beams of the deck should be so disposed as to require no removal in the subsequent alterations of the masts for the various modes of rigging. It is also recommended that T IMPROVEMENT IN NUMBERING HOUSES. the body be clencher-built; vessels so constructed generally excel in sailing such as are carvel made, and this superiority will obtain so long as the resistance of water to curved lines shall be involved in obscurity. It is somewhat paradoxical that constructors of boats for contraband trade should possess such decided advantage over the builders employed by the revenue, as to call forth an Act of Parliament, regulating the extent and the fixing of the bowsprit, and limiting the proportions which the breadth of a vessel must bear to its length. Such legislative interference is detrimental to science: experience teaches us, that attempts to run goods will continue so long as high duties create the temptation; and the boat restrictions, instead of mitigating the evil, have but caused the removal of the capital and skill of the constructors from our own coasts to those of Holland. If a smuggler build a lugger 13 feet beam, 96 from stem to stern, and the bowsprit 60 feet long, why not launch a custom vessel of 100 feet in length: the smuggler, if chased, would use his best endeavours to escape; the revenue officer, actuated by duty and stimulated by hope, would exert his utmost to make a seizure, and the relative success of either party would soon determine the most effective limits of length to breadth. NUMBERING OF HOUSES. 421 SIR,-Encouraged by the favourable notice which I perceive a communication inserted in your 97th Number has obtained, respecting the new London Bridge, I take the liberty to suggest what I think would be an improvement on the method at present pursued, of Numbering the private Houses in this Metropolis. I more particularly allude to the new streets which are now in progress, both in the city and its suburbs; and though I cannot but be aware, that it is a far less important subject to the inhabitants of London generally, than that above alluded to, yet I think you will acknowledge, that it is not a matter of total indifference to that portion of the public who are only occasional visitants. I doubt not that some of your readers, who, like myself, reside in the country, have sometimes experienced the difficulty of finding any particular house in the streets of London, without knowing on which side it may chance to be situated. After walking, perhaps, the whole length of a street, we have discovered that it must be on the opposite side, but which it was altogegether impossible to have observed before, owing to the obstruction of carriages, or other local causes. Although attended with no greater inconvenience than mere fatigue, this is an evil which it is very desirable to obviate. Let not these remarks be misconstrued into an advocation of illicit The plan which I would propose, trade. Taxes must be raised, and is that which is adopted in the cities consequently any person who by of the United States,* and is as simsmuggling evades paying his indivi-ple in theory as it is useful in pracdual share, commits a fraud on the rest of the community, by binding on others the obligation of his own debts. My sole wish is, that naval science may not be injured by legal enactments. On the same principle that laws are made for building and fitting of vessels, why should not others pass, restricting residents on the coast, suspected of contraband addictions, to the services of none but lame horses; whereas all such as are fleet should be devoted to the use of those engaged in the collection of the revenue. tice. It is merely to have all the odd numbers on one side, and consequently the even ones on the other; so that a person can at once tell on which side the number sought is to be found. For instance, we will suppose No. 1 to be a corner house, No. 2 is then the opposite house No. 3 is next to No. 1, and No. 4 adjoins No. 2, &c. and so on regularly to the end of the street. AN ANGLO-AMERICAN. * And also in some of the streets of Edinburgh,-EDIT, 422 ASCENDING AND DESCENDING HYDROSTATIC CARRIAGE. NEW SHIPWRECK SAFETY-MACHINE. An article from Haerlem notices, but very indistinctly, an experiment made at that place with a machine of the singular title of the Sea Phander, which appears to be applied by means of a horse, which, advancing with the machine towards a vessel in distress, conveys ropes to the crew for their preservation. The experiment is said to have been successful, DIFFERENCE BETWEEN HEAT OF FLAME AND HEAT OF NON-LUMINOUS MATTER. SIR,-The study of a poor man, and of a mechanic in particular, should commence with first principles, and the contemplations of the mind will be rendered clear, agreeable, and practical, in the degree that accurate knowledge of first principles may have been established. Solomon, the wisest man, asked for wisdom and knowledge, and the Supreme Ruler added in his grant riches, wealth, and honour. Sir Isaac Newton, the greatest of philosophers, had a character peculiar for mildness, industry, and affability; and relying upon the discovery of first principles, attained honour, power, and affluence, although early educated only at a grammar-school at Grantham. I will, therefore, take this opportunity to repeat a correction of the impression given by our philosophers, that the transmission of solar heat is not interrupted by glass, while that of terrestrial heat is entirely impeded. M. Brande has lately explained the source of error-that the heat of flame resembles solar heat, but that the heat of matter, not luminous, is incapable of penetrating glass. The application of this knowledge is important on a subject occupying many of your pages, viz. the economy of fuel in the furnaces of steam-boilers, The superior power of flame heat can be proved by the fact, that a manufacturer, during a long winter, used some coke; but as it produced no flame, it was found entirely useless. Upon this principle I will conclude, by requesting to know, whether the decomposition of water or steam, applied to aid the combustion of coals, and produce flame, would not give considerable advantage, although the elements of water must be first separated by heat, and exposure to the coals in the furnace; * and, particularly, whether the coke, and substances burning without flame, may not thus be made to burn with flame? Every mode of producing flameof causing economy, by giving the greatest approximation and extension of flame towards the boiler, must be very important; and it is only necessary to observe of flame, that it should not be drawn, like that of a blow-pipe, to impinge on one point, as it speedily destroys the boiler, without producing concomitant advantages. First principles point out the way we should go, and the proper exercise of industry gives a peculiar vigour of mind and saving knowledge in all we undertake; which, that you and your readers may long live to enjoy, is the wish of Your very obedient servant, TYRO. ASCENDING AND DESCENDING A Mr. George F. Reeve, of Orange county, New York, has constructed an engine, which not only exhibits an eccentricity of ingenuity in the inventor, and a pleasing novelty to this manner, with an advantage of 50 Steam has been recently applied in per cent., by Mr. Evans, of Bread-street, Cheapside; but his claim to the first honour of such an application is disputed by Mr. Gilman, and (we believe) by some other individuals. We suspect that the Americans can put in a better title to the discovery than either the one or the other. It is several years ago since the seeming paradox of burning water cut a prominent figure among a number of American wonders newly imported. We intend shortly to give a description of Mr. Evans's apparatus for the pur pose.-EDIT. |