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were left to their fate; and consequently every attempt to throw off their Turkish fetters served only to make their oppressors load them with heavier chains. Gladly, indeed, would the Czars have converted this beautiful country into a Russian province, and would willingly have bartered for it the richest jewel in their crown; but their ambition and cupidity have hitherto been restrained only by the difficulty of the enterprise.

The same selfish policy has dictated the present interference of the Russian autocrat in the liberation of Greece. It cannot be presumed that he, who lords it over a nation of slaves, can have one feeling in common, in such a cause, with the enlightened sovereigns of Great Britain and France, who rule over free-born men. His uniform object has hitherto been territorial aggrandisement and political influence; and his admiral, count Heyden, when he prevailed upon his colleagues in command to destroy the combined fleet in Navarin, had in view ulterior measures, which these officers could not have contemplated. Great Britain and France, by thus admitting the interference of Russia in obtaining a favourite measure, have enabled her to reward herself with a princely remuneration; for we have no hesitation in maintaining, that it was to the destruction of the Turkish fleet, and to the dissolution of the Turkish janissaries, that Russia was mainly indebted for her ultimate success in her conflict with the Ottoman porte. Had this fleet been preserved for the defence of Varna and the coasts of the Euxine, the Russian army would never have crossed the Balkan; or if it had, and the disbanded janissaries of Adrianople had been true to their country's cause, instead of harbouring resentment against their prince, count Diebitsch, deprived of supplies and reinforcements by sea, would in all likelihood have experienced the fate of Peter the Great on the Pruth, at Falczi. Russia, however, is now triumphant, and she may insist upon her adversary paying the uttermost farthing of his bond; but torrents of blood must flow before her plans of aggrandisement be completed; and she may perhaps never again find such a union of circumstances so favourable to her views. She may have also learned, from her own practice and experience, that a treaty made in the hour of peril is considered no longer obligatory when the danger is past; and the present ruler of Turkey will not let slip any opportunity of retaliating upon the foe of his house the wrongs and injuries which have been accumulating for a century.

If Turkey is to be renovated, and to be brought within the pale of civilized Europe, no prince of the line of Othman has ever appeared with qualifications and attainments better suited to its circumstances and its wants than its reigning sultan. Mahmoud II. is at present in the prime of life, be

ing about thirty-six years of age; and the important changes which he has already effected, namely, the annihilation of the turbulent and seditious janissaries, and the subjection of the ulema and pachas to the obedience of the laws, testify his unshrinking courage and resolution. Upon the occasion of the unfortunate battle of Navarin, when all Europe seemed banded against him, his calmness and prudence, though severely tried, did not forsake him; and he evinced a spirit of justice and forbearance very unusual in any prince of his line, in his treatment of foreign merchants, who, while they looked for the usual measures of confiscation and the bowstring, were generously protected in their lives and property. Though conquered, Mahmoud still perseveres with unabated zeal in completing his plans of reform in the military and naval services, and in preparing his empire for future emergencies. By the introduction into his army of European discipline and tactics, and by his own adoption, on many occasions, of the European costume and manners, so obnoxious to the pride and superstitions of Mussulmans, he has shown himself superior to the keenest prejudices of his nation, and is thus gradually freeing himself from the authority of those ancient forms and opinions by which his predecessors were held in thraldom. He has already done much for the advancement of his people in civilization and happiness; and the condition of slaves throughout his dominions has been so considerably ameliorated during his reign, that they enjoy more freedom and comfort than the serfs either of Russia or Hungary. We are afraid, however, that, owing to the vicious structure of society in this country, the religious prejudices and fanaticism of the people, and their general inaptitude for improvement, the task of renovating Turkey will prove too Herculean even for Mahmoud. In the following extract from a recent work on Turkey, the sultan is described as unremitted in directing and managing the affairs of his government: "Il surveille son Divan avec un soin extrême, et ne lui laisse que le simulacre du pouvoir; il dirige, il regle tout par lui-même; en un mot il est lui seul le gouvernement. Mieux et plutôt informé que les ministres au moyen d'une agence secrète três-active, ses mesures sont prises avant que les rapports de son Grand Vizier lui soient parvenus. Actif, laborieux, d'un secret impénétrable, observateur zélé de sa religion, fidêle à sa parole, sobre et respectant les mœurs, Sultan Mahmoud peut être regardé à juste titre comme un phénomène pour la Turquie." See Knolle's Turk ish History; Thornton's Present State of Turkey; Eton's Survey of the Turkish Empire; Upham's History of the Ottoman Empire; Malte-Brun's Geography, vols. ii. and vi.; Foreign Review, Nos. 1, 3, 5, and 6; and Annual Register, vols. xiii.—xix.

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TURNING.

§ 1. UNDER this head we comprehend all operations performed in the turning lathe, in which the object operated on is so disposed as to revolve round its axis, while a cutting instrument is applied to it; or in which it is successively fixed in different positions of its rotation, and then operated on by instruments of various kinds, moving in circles, in portions of circles, in other curves derived from circular motion, or in straight lines.

§ 2. The art of turning in its simple form is of great antiquity, and is susceptible of more accuracy than almost any other mechanical operation. We shall not attempt to give any description of the manipulations required in its application in the more common cases, as these cannot be well learned but by practice, under the guidance of an experienced artist.

§ 3. The great demand for accurate workmanship which has been occasioned by the improvement of the steam engine, and the consequent extension of machinery and manufactures, has led to important improvements in the art of turning. Of some of these we shall endeavour to give such a description as may convey to artists who may not have had an opportunity of seeing their application, some idea of the effects which may be obtained by means of them.

§ 4. The most important of these improvements on the old method of operating by hand-tools, and that on which most of the other improvements are founded, is what is commonly called the slide-rest. This, in what is called ornamental turning, is a small apparatus which is occasionally fixed in the socket of the ordinary rest, (having a cylindrical stalk for this purpose,) consisting of a cutter holder, or carriage which slides along a narrow platform, and is regulated in its motion by a leading screw, which has a small winch, or a milled and divided head at its right-hand extremity.

§ 5. In the best construction of lathe for working in metals, the arrangement is different. The foundation of the slide-rest is a sole A, (Plate DXXVII. Figs. 1, 2, 3, and 4,) which can be fixed at any required part of the bar or bed between the two heads of the lathe. On this sole there is a solid plate B, which slides in a path adjusted truly at right angles to the line of the axis of the spindle or mandril: on this sliding plate, another solid plate C is attached (in a way which will be mentioned afterwards), and on this plate C is formed a slide at right angles to the first one, (and consequently parallel to the axis of the spindle.) On this slide a piece D (sometimes called the saddle) moves; this saddle has an excrescence E rising from its upper surface on that side which is near

est to the spindle of the lathe; it is bored out cylindrically, and forms the socket in which the stem or stalk of the cutter or tool-holder is fixed by a pinching screw G, in the same way as in the sockets of common rests. This socket should be bored truly perpendicular to the planes of the slides.

§ 6. The sliding plates mentioned above are each moved in its own path by a leading screw turned by a winch handle, and it will be obvious that by turning the winch of the leading screw, that plate, with every thing on it, (including the socket E and cutter holder F,) will be made to advance or retire in a direction perpendicular to the axis of the spindle, or of the article to be turned, and that, by turning the winch of the upper leading screw, the saddle D, with the socket E, and cutter holder F, must move in a path parallel to the axis of the lathe, or of the work, and therefore that the article turned must necessarily assume the form of a cylinder. By a combined simultaneous motion of both winches, the point of the tool may be made to pass through any assignable line in a plane parallel to

the slides.

§ 7. As, however, it is often necessary to turn conical objects, an adjustment is provided in the construction of the rest which facilitates the performance of this operation with extreme accuracy. It was mentioned above, that the upper and lower sliding plates B and C are attached to one another in a particular way, which is this: a solid cylindrical pin H passes vertically through both plates near their middle; this pin is screwed into the upper one, but passes through a well-fitted cylindric hole in the lower one B, and so forms a joint round which the upper slide may be turned when the screw is slackened; the edge of the upper plate which is nearest the workman, is a portion of a circle of which the above mentioned joint H is the centre, and is divided into degrees, and marked in such a way that, when the two slides are truly at right angles to one another, the division marked zero is at the index, and the other divisions marked 10°, 20°, &c. on the right and left of zero. When it is required to turn a cone of any particular angle of inclination, the upper plate is turned to the right or left until the corresponding number of degrees comes to the index; it is then fixed in that position by its pinching screws. If the winch of the upper leading screw be now turned round, the point of the tool will describe a straight line having the required inclination to the axis of the work, and so will turn either an external or internal cone according as the cutter and the work may be disposed; ex. gr. the key and the socket of a brass cock may be turned in this way with such perfect accuracy

• In some sorts of work, such as the cutting of teeth of wheels, and drilling deep holes, it is more convenient to take out the leading screws, and to work the slides by levers.

that the one, on being dropped into the other, will be perfectly water-tight without much further preparation or grinding.

§ 8. The great advantages which this construction has over the old one is, that when once well adjusted, it may be successively applied at different situations without any fresh examination or adjust ment; and that, as the socket partakes of the regulated movements of the slides, every instrument or piece of work which is put into that socket, becomes subject to these movements.

§ 9. If, therefore, instead of putting a simple cutter holder (like F Fig. 1 or 4) in the socket, we put any instrument capable of producing a particular effect by a motion of its own, this instrument may (by means of the movements and adjustments of the slides) be made to produce its effect on any particular parts of the work, either in continuous lines, or in parts in a regulated succession, as the work (which will remain fixed while the instrument is operating) may (by means of a divided plate on the face of the spindle pulley) be presented successively in any required number of positions.

§ 10. One of the most useful of the instruments which may be so applied, is a drilling apparatus. Let the reader suppose that a frame containing a strong drill mandril A is so constructed that when it is fixed into the socket of the slide rest, the axis of the mandril is parallel to the path of the lower slide,* and that by some proper arrangement of bands and pulleys this drill stock can be made to turn with the requisite velocity; next let him suppose a drill in the stock, and a cylindric piece of work in the lathe, then if the pointer be applied to any of the holes in one of the circles, in the face of the pulley (of the spindle) having twelve divisions, one or other of the following effects may be produced.

1st case. If, while the drill mandril is revolving, the winch of the lower leading screw be turned forward, the drill will advance and will continue to pierce a hole towards the axis of the cylinder. If the drill, after going to a certain depth, be with drawn clear of the hole, and the work be turned round until the pointer falls into the next hole in the divided circle of the pulley, the drill may be again advanced to perforate a second hole, and so on until the number 12 is completed. In this way sockets for the spokes of a wheel may be accurately bored, or any analogous operation may be performed.

§ 11. 2d case. But with the same preparation a different effect might have been produced. After the first hole had been made, if instead of turning the piece of work in the lathe 1-12th part of a circle, we had turned the winch of the upper lead. ing screw a certain number of turns, and then had drilled a second hole, and if we repeated this alternate operation 12 times, we should then have had 12 holes as before, but with this difference, that they would now be disposed in a straight line parallel to the axis of the cylinder.

§ 12. 3d case. Again, with the same preparation, a third effect may be produced. Suppose the first hole pierced as before, and the drill withdrawn from it, then if the work be turned round 1-12th of a circle, and also the upper winch turned as many turns as in the second case, the second hole, when made, will be found to stand diagonally to the first; and if the operation be repeated 12 times in the same way, the 12 holes will have taken a helical direction round the cylinder, and if short spokes were fitted into them, they would stand like what are called the pins of a wiper beam.

§ 13. 4th case. If the drill, instead of being allowed to penetrate so far as to make a hole, were stopped in its advance when no more than its cutting part had entered the substance of the work; and if, while in this situation, the winch of the upper leading screw were to be turned (the drill still continuing to revolve), its point would necessarily cut away the substance of the work in the direction in which it was led by the screw, and would in this way cut a longitudinal furrow instead of a circular hole. The shape of the bottom of this furrow would depend on the form of the point of the drill.

14. In these four cases we have supposed the drill to be capable of drilling holes only at right angles to the axis of the work, but this would obviously be too limited a range of operation. It is necessary, therefore, to have some means of advancing the drill arbor independent of the action of the lower leading screw, and this is done by having a slide B in the construction of the instrument itself, as seen in Fig. 5. This slide is parallel to the axis of the drill arbor, and as the instrument, when put into the socket of the slide rest, may be set with its own slide obliquely to the work (having divisions and an index as at C for this purpose), the advance of the drill into the work may be made in any required direction, while its other movement will depend as before on the leading screws of the slide rest.

§ 15. The term drill has been used here to designate the cutting part of this instrument, but this must not lead the reader to suppose that the form of the cutting tool is limited to that usually seen in boring instruments. Revolving cutter would be a better designation, were it not appropriated to another instrument, of which we shall have to speak presently. In point of fact, an endless variety of cutters may be employed in a well constructed apparatus of this kind, and effects may be produced by a judicious application of them, which, until lately, were never attempted by the turner. The nose D of the arbor may be screwed like that of the spindle of the lathe, and by means of metal chucks (similar to that shown at N, Fig. 2, Plate DXXVI.) fixed on it, eccentric cutters of various kinds may be employed according to the wants of the artist; this will be understood by inspecting the figure. We cannot, according to our prescribed limits, go further into the detail of the adaptations of this useful instrument than just to show, by way of example, how it may be employed to produce flat

*In Fig. 5 the drill mandril has been represented in a position parallel to the path of the upper slide, and to the axis of the lathe, i. e. in a position for drilling face work.

surfaces in different parts of the same piece of work.

§ 16. Let us suppose we have turned a sphere of ivory from which we want to cut away such portions as would leave a cube. It is obvious that in the old way of turning by, by making the work revolve and the tool remain comparatively at rest, that only one of the six faces could be cut in this way without removing the work from the chuck; and that the greatest possible accuracy in refixing it after removal, could hardly ensure a successful

result.

§ 17. By means of the instrument just described, the whole six faces may be prepared without unfixing the work from the original position in which it was made into a sphere. We shall suppose, then, that the sphere is attached to the chuck by a neck strong enough to bear the operation of cutting the planes, and that we have ascertained the exact length of the side of the cube contained in the given sphere. The first thing to be done is to select some circle on the pulley of the lathe spindle divisible by 4, into one of which divisions we fix the pointer. We then choose an eccentric cutter for the drill arbor, similar to that seen in Fig. 2, Plate DXXVI. the sweep of which must include a circle whose diameter is something greater than the side of the intended cube: the form of its cutting edge is not very material in the first stage of the operation. The slides of the rest, and of the drill apparatus being set accurately at their respective zeros, and the arbor itself being somewhat to the right hand of the piece of work, it must be set in motion by the band, and carried to the left by the upper leading screw until the cutter just begins to impinge on the surface of the sphere. The depth of cut is of course to be regulated by the lower leading screw, and should not exceed 1-40th or 1-50th of an inch each time; in this way, by making the cutter repeatedly pass from right to left over the face of the sphere, advancing the lower slide each time by the depth of a fresh cut, one face of the ball may be cut down nearly to the required depth. The index point is then to be made to fall into another quadrantal division, and the same operation repeated to the same depth, and so on with the two remaining ones. When the first face has been cut away, the plane face will be bounded by a circular line; but when a second has been cut, the intersection of these two planes will form a straight line which should, in this stage of the operation, be a little shorter than the side of the intended cube. A new very sharp cutter should now be fixed in the chuck of the drill arbor, having its cutting edge straight, and truly at right angles to the arbor; with this the same operation must be repeated on all the four faces, until the lines of intersection of the four planes be exactly equal to their breadth, and the planes them selves perfectly smooth. Instead of the eccentric cutter, a cutter like a small circular saw might have been fixed on the nose of the drill arbor, and the four lenses cut off the sphere in succession, but the same smooth finish could hardly be given in this way, and the diameter of the saw would require to be more than twice the size of the cube to enable VOL. XVIII. PART I.

it to cut off the slice without the neck of the arbor interfering, the friction would consequently be great. § 18. The drill apparatus must then be removed from the slide rest, and the pointer from the divided circle, so as to leave the lathe and work free to revolve. The ordinary cutter or tool holder is then to be put in the socket of the rest, and furnished with a well set parting tool. This tool is to be brought by the leading screws to the proper position for making a cut perpendicular to the axis of the work at the right hand extremity of the intended cube; the work being then put in motion, and the tool advanced by the lower winch, a fifth plane will be cut on the end of the work, and a slice of the form of a plano-convex lens will be cut off; this face being completed, either at one or at repeated cuts, the place of the tool holder must be shifted by the upper leading screw, to permit the cut to be made which is to form the sixth face, and of course to detach the cube from its connexion with the mandril. § 19. It will be evident to the reader that if the operation be conducted with proper caution, and the divided circle on the pulley be accurate, the result must necessarily be an accurate cube. The intelligent artist will also see, that by a slight variation of the process other geometrical solids may in like manner be produced, and many analogous operations performed.

§ 20. We mentioned above that the name of revolving cutter was appropriated to another instrument which may (like the drill apparatus) be applied in the socket of the slide rest. When a lathe is provided with well divided circles on the pulley of its mandril, and a properly constructed revolving cutter apparatus, it becomes an engine of extensive powers for cutting the teeth of wheels.

This instrument consists of a frame carrying a spindle A, generally vertical, but which may be set (within certain limits) at any degree of obliquity in a

vertical plane, and round a centre which is in the plane of the axis of the lathe. In all the positions which it can assume, except the horizontal, its lower extremity or point B is below, and its upper collar or neck C is above the plane of the centres of the lathe. At a point between the pivot and collar, and exactly level with the lathe centre (and consequently with the centre of its own adjustment) circular cutters (as at D) like those of a clockmaker's engine, may be fixed on the spindle. Let us suppose the spindle in the vertical position, fitted with a cutter, and a piece of work in the lathe in which it is required to cut 120 teeth. It will be seen that all we have to do is to bring the revolving cutter directly opposite the edge of the work, to select a circle on the pulley of 120 divisions, and having fixed the pointer in the first division, to advance the cutter against the work by the lower leading screw to the proper depth. to the proper depth. This being repeated for each of the 120 divisions, the operation is completed. If, instead of a thin wheel, the work be a pinion of considerable length, it may be necessary, after having made the first cut to the proper depth by means of the lower leading screw, to extend the cut to the right or left by means of the upper one; in such cases, it is best to make all the cuts after the

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first, by means of the upper winch alone, winding the cutter clear of the work each time to allow for the shift being made in the divided circle.

§ 21. We have said that the cutter spindle may be set obliquely, or even horizontally. This is effected by making that part of the frame, in which the step and collar of the spindle are formed (see E, Fig, 6, Plate DXXVII.) turn on a centre which passes through the portion of the frame which is fixed in the socket of the slide rest. This centre is level with the centres of the lathe, and consequently, whatever angular position the spindle may be put in, the circular cutter will always tend to cut directly towards them.

§ 22. Many operations besides the cutting of the teeth of wheels and pinions may be performed by this apparatus, as the form of the cutters, the position of the spindle, and the movement to be given to them may be varied in many ways by the intelligent artist, according to the purpose he has in view. § 23. In all the cases subsequent to § 9, we have supposed the work or article operated on to be fixed in the lathe (by means of chucks or otherwise) and the cutting instrument to be in rapid motion round its own axis. There are cases, however, in which the situation of the work and the tool may be reversed, the work may (by different methods according to circumstances) be fixed in the slide-rest, and the tool may be fixed in, or on, the nose of the lathe mandril.

§ 24. In this way a piece of wood or metal which is to be sawn in parallel cuts, or cuts at certain inclinations to one another, being properly made fast to a frame or vice held in the socket of the sliderest, we may cut it in a variety of planes by a circular saw fixed on the lathe mandril, because by means of the divided arch on the upper slide of the rest, we may set it to the required angle, and then by the lower winch we may advance it against the edge of the saw.

25. Instead of a circular saw, we may put drills of large sizes into the lathe mandril, and fixing the article to be bored on the slide-rest, we may present it, and advance it against the drill by means of the leading screws. This process will often be useful when the drill is large, and the resistance too great to be conveniently overcome by the apparatus described in § 10, &c.

It may sometimes happen that the risistance is too great to be easily overcome by the leading screw of the upper slide. In this case it may be as well to disengage the leading screw and winch, and to bring the moveable head of the lathe so close to the work, that the upper slide, together with the work on it, may be pressed towards the drill, by the screw of the right hand head stock.

§ 26. We have endeavoured in the foregoing paragraphs to give some indications of what may be done in a lathe with a well constructed slide-rest. The intelligent artist will see that by some of the contrivances pointed out, or by some modification or combination of them, he may perform with comparative ease, and great precision, many operations which, in the ordinary way, must be done in the vice by chipping and filing; and which would con

sume much time even in the hands of the most expert workmen. In good slide-rests there are stops and adjusting screws for regulating the depth and length of the cuts. We have not attempted to describe them, as this would lead us into too minute a detail. Some of them may be seen in the engravings.

$27. In machine maker's work-shops, where heavy work is turned, such as shafts, large rods of steam pistons, &c. the slide-rest is differently constructed, and is more strictly what its name indicates. Instead of a part of it being fixed to the bed, and the saddle with the cutter holder being made to slide on it by a leading screw within itself, the whole body of the rest is made to slide to the right or left along the bed of the lathe, sometimes by an endless screw within itself, which works into a kind of oblique toothed rack, extending all along the bed, and sometimes by a leading screw of the length of the bed which works in a female screw socket in the sole of the rest. This leading screw is worked by wheel work from the lathe mandril, and the requisite degree of speed is given to the motion of the rest by proportioning the sizes and numbers of the wheels, pinions, and pulleys. § 28. By this last arrangement, a very convenient method is obtained of cutting long screw bolts, or original screws of every variety of pitch, as we have only to put on such trains of wheels and pinions as we ascertain by calculation to be necessary to give the relative degrees of velocity to the mandril and to the cutter in its motion to the right or to the left, and we shall then, by presenting a cutter of proper form, succeed in cutting a screw of any length which the lathe can take in. If the cutter moves to the left while the work revolves the right way, it will cut a right hand thread; and if it move towards the right, while the work is revolving the right way, the result would be a left hand thread of the same pitch. The thread will be angular, square, or round, and deep or shallow, according to the form of the cutter which may be selected.

§ 29. The female screw or nut of the same pitch may be cut in two ways.

1st. The work to be screwed may be chucked, and a hole of the proper size having been bored in it, a side cutter being presented either at the mouth of the hole, or at its bottom (according as the thread is to be a right or left one) the lathe being then put in motion, the tool will advance or retreat (as the case may be) while the work turns round, and the thread will be gradually cut to the proper depth.

2d. If the work be of such a nature that there are a succession of holes to be tapped, it may be fixed on the slide-rest, and one of the holes brought truly into the line of the centres; then by means of a revolving cutter (of one point) fixed in the lathe mandril, the thread in the hole may be gradually cut to the required depth by increasing the eccentricity of the revolving cutter at each shift of motion. The other holes in the work must then be brought in succession (by means of the slides of the rest) into the line of the centres, and the same process repeated.

In this process, the motion of the lathe mandril

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