on which the carriages may roll with ease,|| if the railway is not kept in good order, or if it does not answer the intentions for which it was established, it is clear that the rasistance the train will oppose along those rails will be so much the greater. The same will also take place if the carriages, being ill-constructed or badly repaired, have a considerable friction. ATLAS had, on July 23, on an inclined ran to the end of the balance, marking 220 plane at 1300, drawn 40 wagons, weighing lbs. As, however, this case happened only 190 tons, and the diameter of its cylinder accidentally, it could not be considered as was only 12 inches. According to the ideas an effect of the regular draft: and, indced, admitted on the railway, on the resistance after the shock which had caused this exof the trains, this fact could only be ex-traordinary excursion, the needle immediplained, by supposing either that the pro-ately returned to its usual point of 100 lbs., portions of the engine were not exactly and began again its oscillation between 50 what they were thought to be, or that the lbs. and 170 lbs. After having, to no purFrom this observation, we see that the railway had a different inclination from pose, waited to see whether the motion power required to draw a given weight, a what was computed, or the train a different would become more regular, we concluded ton for instance, cannot be the same upon weight from that inscribed on the weighing that the experiment was not suspectible of all railways, nor with all sorts of carriages. books. Other experiments, however, made a greater degree of precision. On perfectly smooth rails, and with a well- by us with other engines, in other circumgreased and well-constructed wagon, the stances, and in other points of the railway, draft of a ton may require only a power of 8 having given similar results, we were allbs. We mean to say that a weight of 8 lbs. ready convinced that the friction of the suspended at the end of a rope passing over wagons could not exceed 8 lbs. per ton, and a pulley, will, in that case, be sufficient to that the mistake lay there, unless wo premake a loaded carriage, weighing a ton, ferred supposing that mistakes had been move forward. On another railway, on the||made in the dimensions of all the engines, contrary, and with carriages of another and in the levelling of all the parts of the construction, the same load of a ton may road. more. namometer. The variations of the needle between 50 lbs. and 170 lbs., gives an average of 110 lbs. The three wagons weighed together 14.27 tons. So the experiment gave 14.27 or 7.70 lbs. resistance per ton. 110 larly as the speed was only three or four miles an hour. All the direct resistance of the atmosphore took place on the first carriage of the train, with which our experiment had nothing to do. This approximation, as it was, might be be useful, but it was thought necessary to obtain more positive results. It is important to remark, for what will be said hereafter, that this experiment was free from the direct resistance of the air; require a power of 10 lbs., and perhaps It became, therefore, necessary to ascer- for these three waggons, being the last of tain the fact in a direct manner, by estab-the train, underwent from the air only a very The old wagons, on which some experi-lishing a series of experiments for that inconsiderable lateral resistance, particuments had been made, required a power of purpose; but it was particularly satisfactory 10 lbs. to 12 lbs. for each ton weight of the to have been led to the knowledge of the load. Since that time, the carriages had truth by the calculation, as the experiment been brought to greater perfection, and had became thus the verification of it. never been submitted to any experiment made on a large scale, and in the usual § 2. Of the Friction determined by the Dyworking state. At the time of the introduction of the new wagons at Liverpool, The most natural means of determining one trial had been made with a single wag- the friction or resistance of the wagons, In consequence a convenient place havon, and just at the moment it was coming seemed to be the dynamometer, which gives ing been chosen on the Liverpool Railway, out of the hands of the maker. But as directly the force of traction required to exe-at the foot of Sutton inclined plane, and at that wagon had been carefully oiled on pur-cute the motion; but as the act of drawing, a distance of 111⁄2 miles from Liverpool, pose for the experiment, and as it had not either by men or any other living moter, the level was taken in the most accurate yet encountered any shock by which the takes place by starts, the dynamometer os- manner, to a tenth of an inch, and the exaxles might have been bent, the wheels cillates between very distant limits, and periments commenced on the following warped, or the hind wheels prevented from can give no certain result. It appeared, principle :following exactly in the track of the fore however, to us, that if the draft were effect-§ 3. Of the ones; and as, moreover, the rails had been ed by an engine, the effort of which is alnicely swept, the result of such an experi- ways equal, and the motion regulated by the ment could scarcely be considered as a mass of the train itself the oscillation of Let us suppose a heavy body left to itcommon practical result; and, in fact, the the dynamometer would not be so great, self on an inclined plane AB (fig. 23,) and friction of the trains continued to be calcu- particularly if the instrument were to be sliding without friction to the foot of the lated on the Liverpool Railway at the rate fastened to one of the last carriages, on plane; let us suppose at that point another of 10 lbs. per ton. These uncertain data which the pulsations of the engine have nat-plane, being the continuation of the first, could not be admitted in a new work on the urally much less effect. and on which the same body continues its subject. motion. Therefore, at the moment the LEEDS engine was setting off with a train of 12 wag Friction determined by the Angle of Friction. It became therefore necessary for us to The body will descend along the plane, find another base for the calculations that ons, after the whole mass had been put in by virtue of its gravity; but that force will were to be made on modern wagons. How-motion, and while the motion continued with act only partially: it will bo decomposed ever, the occasion which gave rise to the an uniform velocity of three or four miles into two others, one perpendicular to the experiments we are going to relate, occur-an hour, the chain of the three last carria- plane, which will be destroyed by the rered in the work of the locomotive engines. ges was unhooked, and replaced by a circu-sistance of that plane, and the other in the They pointed out themselves, in a way, the lar spring-balance, which had been prepared effect, and will be the accelerating force of sense of the plane, which will have its full errors committed in the appreciation of the for the purpose. The rod of the balance resistances they overcame. the motion. If therefore g express the inThis point is was fixed to the frame of the ninth wagon, worthy of notice, as it proves at the same and the three following, which were the last tensity of gravity, and the angle of the time both the perfection of the engines, and of the train, were fastened to the spring. force of the motion will be plane, with a vertical line, the accelerating the correctness of the calculations, to which The experiment took place between the it is possible to submit them. It inspires milestones one and a half and two of the consequently more confidence in the other Liverpool Railway, on a space of ground results which were obtained in the same which is a dead level. way, and it is for that reason we mention it. We expected to see the index of the balHaving made, during our stay at Liverpool, ance remain nearly steady; but we were in 1834, a great number of experiments on disappointed. Its average position was the power of locomotive engines, we found near the point marking 100 lbs. ; but it unthan one of those experiments, made with derwent very great variations, that is to say, the ATLAS, and which we shall have occa- from 50 lbs. at least, to 170 lbs. at most; Besides, when we consider only an insion to relate hereafter, appeared to exceed and even two or three times, at certain ex-finitely small interval of time, any motion the limits of the power of that engine. The traordinary starts of the engine, the needle may be regarded as uniform, which, by ex ❤= g cos'; v but the general expression of any accelerating force is = ., v being the velocity and the time; consequently g cos è' = t pressing by a the space passed over, gives out any friction or resistance whatever. In F, and making those two substitutions, the g cos 0' x. This equation gives the velocity of the moving body in any point whatever of the first plane. Consequently, if we express by x' the distance of the point B, from the starting point, measured along the plane, the velocity of the falling body, when arrived at that point, is V2g cos 'x'. that equation we see that we can only have equation may be written in the following form: = PzF(x+x'). Let us suppose, then, that, having left in the beginning the moving body free on the inclined planes, it has descended to the point m, for instance, and has not gone But if the body moves with the friction, farther; that point must necessarily fulfil experience having proved that friction does the above condition, else the moving body not increase with the velocity, it will act as would not have stopped there. If, therean uniformly retarding force, contrary to the fore we measure on the spot the quantities gravity along the plane. By the introduc-z, x and x', and know the weight P, the tion of that new force, the accelerating forces equation will contain no other unknown of the motion on each of the planes will no quantity but F; so that equation will give us its value, viz. longer be F=Px+x but g cos é', and g cos "; g cos 'f, and g cos "-f, of = 2 (g cos" —ƒ) x + 2 (g cos 8' —ƒ) x.' Effecting the indicated operations, and substituting z" for x cos 8', z' for x cos d' and for 2+2", we have - Consequently, when a body of a given weight P, placed in the above stated circumsances, stops in descending at a certain point m, the value of the friction that stopped it, will be found by dividing the total height from which the body descended by the total distance which it travelled over. This determination once made, it is clear that if we were to construct an inclined plane, the height of which were z, and the length r+r', and if we were to place the anybody on it, it would remain in equilibrium. In fact, the gravity that tends to impel the body onwards would be exactly equal to the friction that retains it. In that case the velocity in any given point m of the second plane, the distance of which to the point B is expressed by x, This is the velocity the body has acquir-will consequently be ed, at the moment it is going to pass from v the first to the second plane. This velocity being applied to it in the direction of the first plane, would produce, in the direction of the second, only a certain velocity, resulting from the relative inclination of the two planes, if the passage from the one to the other took place abruptly. But if the passage is effected by a continued curve, we know that there will be no loss of veloc-v= ity, and the body will begin its motion on the second plane with the same velocity it had in leaving the first. This will, therefore, be its velocity in beginning its descent on the second plane. The body will, besides, continue to be impelled by gravity. " being the angle of inclination of the second plane with a vertical line, the gravity will produce an accelerating force gcos "; and by a calculation similar to the former, we will also have on that plane, v3= 2g cos x C. In this equation, C is determined by the condition that a = o must give for the incipient velocity of the second motion; and as we have seen that this incipient velocity is it follows that V2 = 2g cos 'x', C=2g cos 'x'. Substituting that value of C, the velocity in any given point of the second plane is expressed by 2g cos x + 2g cos d'x'. Further ' and 2" being the vertical heights gone through on each plane by the moving body, we have x' cos d'z', and r cos "z". Consequently the equation may be written. in the following form: or v2 = 2g (z' +=′′) ; v2 = [gz -ƒ (x' + x)] ; o, unless z = 0, x' : gz —ƒ (x' + x) = 0. If, therefore, a body once put in motion gz = f (x' — x). gMz=ƒM (x + x'). From a point taken on Sutton inclined gM is its action on the whole of that body, plane, at 50 chains from the foot of that or its weight which we shall express by P. plane, 34 distances of 10 chains or 330 Also f is the retarding action of the fric-feet each were measured. At each of these tion, as relates to a single element of the points a numbered pole was fixed in the moving body. But the friction being pro- ground, and the level exactly taken. The portional to the weight, f M is the friction following table shows the result of the lev when we consider the whole mass of the elling operation expressed in feet and deci. body. Expressing, then, that friction by mals of feet. 9 10 11 34.61 Foot of the inclined plane, or rather middle ponit of the continued curve. 35.06 12 35.19 13 4,290 35.23 14 8 Number of Weight the wagon. loaded. No. 294 tons. Distance Difference Friction gone through. of level. Friction. per ton. feet. feet. 4.65 7,326 37.16 1 100 5.15 . 6,663 36.95 : 13.28 taken On the ground where the experiments || constructed on that principle, they having took place, a little beyond the foot of the been only meant as a trial, the advantage of inclined plane, the wagons had to cross which has not yet been confirmed by exthree junction roads, each of them necessi-perience. I. On July 29, 1834, five wagons tating the passing over three switches, as may be seen in fig. 24. This made in all at random, and loaded with bricks, were nine switches, either on one side of the rails brought to the spot fixed for the experiments or the other. On passing each of these ob- by the SUN engine. The train was followed stacles, the wagon received a jolt from the ed by a sixth empty wagon. The weight unevenness of the road, and their velocity of five wagons together, accurately taken was checked. The ground was conse- with their load, amounted to 30.65t, and quently unfavourable for experiments, and including the weight of ten persons, not made the friction appear rather more con-weighed with them, to 31.31t., or to 6.26t. siderable than it really was. per carriage. or VI. empty wagon, The wagons used for the experiments The middle of the train having been are of the following construction. They carefully, placed facing the starting point consist of a simple platform, supported on on the plane, and the engine being taken four springs. Their wheels are three feet away, the brakes were taken off all at in diameter, and fastened to the axletree once, at a given signal, and the five wagwhich turns with them. The body of the ons were left to their gravity on the plane. carriage rests upon the axletrees, but out- They continued their motion till 33 ft., beside the wheels; that is to say, that the beyond post No. 30, having thus run a to axles are prolonged through the nave, in tal distance of 9933 feet, with a difference order to support the carriage. At the of level, between the points of departure bearing they are turned down to 1 inches and arrival, of 38.55 feet. The wagon, No. 100, at the moment it in diameter. The chair is made of brass By recurring to the principle laid down arrived, had one of its axle-boxes very hot, at the bearing-point. In its upper part it above, we had, in this experiment, x+x=which explains why it did not continue its 38.55 feet and the friction motion as far as the others, though equalcontains grease, continually feeding upon 9933 feet, x= 38.55 1 ly loaded. The empty wagon was very the axle through a hole in the chair, and of the weight. was the 99.33 258 the waste of which is prevented by a cover low, being formed only of a platform suron the underside of the chair. The grease- Consequently, the friction of a ton was rounded by an open railing. box, which is filled every morning, is suf- 1t. According to these experiments, each of 2240 lbs. 8.69 lbs. This friction, the loaded wagons, taken separately, had ficient for the whole day. In the experi- 258 258 ments, no alteration whatever was made to however, included the resistance of the an average friction of 11.3 lbs. per ton; and the usual disposition; every thing was left air, and was augmented by the above-men- those same five wagons, united together in as it is in the daily work, as well in regard to tioned circumstance, of the passage of nine a train, had only a friction of 9.17 lbs. per ton. The difference in favor of a greater the wagons as to the rails. Among the switches at the foot of the plane. II. After this first experiment, 300 bricks number of carriages was evidently owing wagons there are some, the extremity of the axle of which, instead of being from were taken out of each of the wagons. to the resistence of the air, the effect of one end to the other of an uniform diame- The weight of 100 of those bricks having which only takes place on the first carriage. ter of 14 inches, is thickened near the been carefully taken, and found to be 855 If the train is composed of only one wagon, frame of the carriage by three eighths of lbs. ; this was, consequently, an alleviation that one must bear alone the whole resistan inch, and is on the contrary diminished of 2,565 lbs. or 1.145t. for each carriage. ance; but if it is composed of several, the as much at the other end. Consequently, The weight of the five loaded wagons, in-resistance of the air remaining the same, is that part of the axle is composed of three cluding the same 10 persons, amounted thus divided between all the wagons, and becylindrical parts equal in length, and the di- to 25.58t. or 5.12t. for the average weight comes consequently less peecestible on each ameters of which are, 2, 13, and 1 of each of them. The same effect may be obinches. served in the first experiment compared The number of carwith the second. riages was the same in both, but the first train being more heavy, the resistance of air was distributed between a greater aumber of tons. This disposition is adopted, in order to leave the mean diameter as it was at first, but to give, however, a greater strength to the point which appears to suffer the most. There are, nevertheless, but few axletrees In this state the wagons were brought back to the same starting point as at first, and left again to their gravity on the plane. They continued their motion until 84 feet beyond the post No. 28, having gone through a total distance of 9324 ft. on a of them. It appeared therefore necessary, in order complete our investigation, to make other experiments, with trains of different weights and in different circumstances. In the following experiments the wagons were no longer loaded with bricks, but with goods. of different sorts, such as were furnished by the trade in the common business of the railway. each of them. The 19 gravity on the plane, and ran till 108 ft.||ately afterwards, and of which we shall XII. The same day 24 wagons were brought to the same place by the ATLAS engine, these 24 wagons weighing to gether 104.50 t., and making with the tenVII. The following day, July 30, a trainder of the engine, which weighed 5.50 t., of 19 loaded wagons was brought to the 110 t. for 25 carriages, or 4.40 t. per carsame place by the MARS engine. riage. They were left to their gravity on wagons weighed together exactly 92 tons, the plane, and did not stop until they reached giving 4.84 tons for the average weight of 108 feet beyond the post No. 32. They The train was again stop-ran, consequently, over a space of 10,668 ped on the plane, so as to make the middle ft., with a descent of 38.82 ft., which puts or centre of gravity of the mass exactly the friction at, or 8.15 lbs. per ton. facing the post No. 0; and the whole was left to its gravity as in the foregoing experiment. The mass being put in motion, stop So pcd at 168 ft. beyond the post No. 32. the space gone through was 10,728 ft., and the difference in level between the starting and stopping points was 38.85 ft., which made the friction equal to 4 of the weight, or 8.11 lbs. per ton. 》:6 Lastly, complete trains, that is to say, the engine, tender, and wagons together, were brought to the trial of gravity on the plane, and gave the following results : XIII. On the 2nd of August the FURY engine, followed by its tender and by 17 wagons, weighing as follows: wagons 81.26 t., engine 8.20 t., tender 5.5 t., together 94.96 t., was left to its gravity on VIII. The same day the same experi- the plane. The engine and its tender being, ment was made with the tender of the Ju-on account of their weight, reckoned for PITER engine, which stopped at 27 feet be- three wagons in the position of the centre of yond the post No. 18, and its friction was, gravity of the mass, the whole was considconsequently, including the resistance of the ered as equal to 20 wagons. The train air,, or 13.76 lbs. per ton. was consequently stopped so as to place is nothing but a wagon of a particular form, facing the starting-post, the interval between giving, comparatively, a considerable hold the seventh and eighth wagon. The mass, to the air, particularly when it is not much being put in motion, stopped at 42 ft. beloaded. The tender of the JUPITER was yond the post No. 34. It had run over then nearly empty, having only sufficient 11,262 feet, with a descent of 39.10 ft.; provisions to bring back to Liverpool the 1 of the weight, This tender persons that were present at the experi-which put the friction at 283 ment. This as well as the preceding day's experiments were made jointly with Mr. H. Earle, one of the directors of the railway; Mr. J. Locke, engineer of the Grand Junction Railway; Mr. King, of the Liverpool Gas-works, and other persons more or less directly connected with the administration of the Company. IX. On the 31st of July the tender of the ATLAS engine, then weighing 5, t., was left to itself from a point situated at 84 ft. below the post No. 1. It stopped at 90 ft. beyond the post No. 23, having run over a space of 7,266 ft. by 32.88 ft. descent, which gives for the friction, or 10.13 lbs. per ton. or 7.78 lbs. per ton, including the engine, XV. To conclude, on August 15, the LEEDS engine, weighing 7.07t., followed by its tender and a train of seven wagons, the aggregate weight of which, besides the engine, was 33.52 t., was also submitted to the same experiment. Starting exactly from the post No. 0, it ran till 255 ft. beyond the post No. 24. Distance 8,175 feet; descent 37.35 ft.; friction of the whole, or 10.23 lbs. per ton. The whole train weighing 40.59 t., had therefore a total resistance of 415 lbs. ; and as the engine submitted alone to the experiment had been found to have 112 lbs. friction, on those 415 lbs. there were only 303 lbs. applicable to the wagons and tender, and consequently the resistance belonging to the train was, or 9.04 lbs. per ton. (To be Continued.) MORTICING MACHINE.-The following cut represents a Morticing Machine, exhibited at the Fair of the AMERICAN INSTITUTE, in October last, by Mr. George Page, of Keene, New-Hampshire, to which was awarded a silver medal. This simple and unpretending machine was viewed, and its operations witnessed, by a large number of practical mechanics, who were highly gratified by the rapidity and precision of its movements, and the wonderful accuracy of its work. Any person could, at once, perceive that, with ordinary care, and a few hours' experience, any man can per form as much labor in one day, with this The whole weight of the train, engine machine, as in a whole week in the or included, was 94.16 t. The resistance of the whole, taken at the rate of 7.78 t. as it dinary mode. Such, indeed, is the simplihad been found, was then 733 lbs. But city of its operation, and economy of its the engine, submitted alone and a moment use, that over three hundred machines have before to the experiment, had been found been sold since the Fair in October last; and to have 113 lbs. friction, as we shall see it is probably not too much to say, that the below. Of these 733 lbs. there were, consequently, only 620 applicable to the wagons and tender. Their aggregate weight was 85.96 t.; consequently, the resistance belonging to them was 7.21 lbs. per ton. owners of them have, on an average, saved twice the cost of them, in addition to the great advantage and convenience in forwarding work during the present scarcity and high prices of labor. A small proportion, however, of those mechanics who have morticing to do, have yet obtained them. A small number only of those journeymen who work by the piece," have yet con XIV. On the 2nd of August the VULCAN engine, weighing 8.54 t., followed by a train of twenty wagons, weighing 96.30 t., X. The same day the train led by the and by a tender weighing 5.5 t., forming same ATLAS engine, composed of 14 wag- together a mass of 110.14 t., was brought ons, weighing together 61.35 t., was left to the place of the experiments. Not hav-sulted their own interest by adopting them. to its gravity on the plane from a point sit-ing been able to stop the train in time, it A few, however, who view things properly, uated at 24 ft. above the post No. 1. Not could only depart from a point situated at have got them, and are, consequently, enahaving at our disposal a sufficient number 18 ft. below the common starting-post, the bled to do much more work, and, of course, of men, the train could not be stopped be- engine and its tender being reckoned tofore. It ran to 15 ft. before the post No. 5;gether for three wagons, in fixing the situathat is to say, over a space of 9579 ft., in a descent of 35.32 feet, which gives for the friction, 8.26 lbs. per ton. 1 to earn more money, than was possible before. If a man, who worked on bedsteads, for instance, which have much morticing, could formerly earn $15 a week, he can now do the same morticing in one-sixth or one-eighth of the time, and, of course, do more work, and certainly do it better. Indeed, any man who has much morticing to do, will save the cost of a machine in a month, and even less. tion of the centre of gravity. The mass stopped at 39 ft. beyond the post No: 33. The distance ran over in 12' 10" was 10,911 XI. On the 1st of August a train of 10 ft., on a descent of 38.75 ft. The friction wagons was brought to the place of the calculated over the whole was consequently experiments by the VESTA engine. The of the weight, or 7.96 lbs. per ton. 10 wagons weighed together 43.72 t. The total resistance for the 108.50 t. The tender of the engine, weighing 5 tons, weight of the whole train, engine included, was left attached to them, making thus to-was 863 lbs.; if from that we deduct 127 gether 48.72 t. for 11 carriages, or 4.43 t. lbs. for the resistance of the engine itself, This machine may also be used, with a or carriage. The whole was left to its according to an experiment made immedi-little alteration, for morticing hubs, for car cast steel, about six inches in length, and from one-eighth to an inch in diameter.The cut is perpendicular on one side, and beveling on the other, with side cutters, projecting backward about one-fourth of an inch, which serve not only to make the sides of the mortice as smooth as the ends, but also to clear the chips, as the chissel is withdrawn from the mortice. This chissel is either single, or double, cutting one or two mortices of equal width and depth at the same time. It has also a tool for making dowells, and another for cutting holes in Venitian blinds, for the cord to pass through. The two latter are of much use, especially that for making dowells, or pins, of any size, from onefourth to an inch in diameter, and 4 to 6 or 9 inches in length; and the other performs, at one pressure of the foot, an operation which in any other way requires five times the labor. f, The stop, which is made fast to the upright by a bolt and thumb-screw, to prevent the timber from rising when the chissel is drawn up by the spring. g, g, The connecting rod between the lever h and the treadle. This rod is movable to accommodate the depth of the mortice. h, The lever, passing through the upright post and front brace, to which it is connected, in front, by two straps of iron. The lever, is about three feet in length, and at its extreme end connected with a spring-poll to raise the chisel from the mortice. i, i, The treadle, or foot-board, by which the machine is put in motion. This footboard is also, like the lever, about three feet in length; passing through a long mortice in the lower part of the upright post, and made fast at the back end, to a short upright standard, rising about 14 inches from one an iron rod in the rear of the upright post, of the cross sills. It is then connected by with the lever at the top, which rests upon the slide d, d, into which the chissel is in riages, waggons, &c.; and an experienced An hundred others who have used them hand can prepare and mortice a sett of com-might also be named if it were necessary, mon-sized carriage hubs in ths of an hour, but it is not, as all the descriptions and with ease, and do them far more accurately opinions in the world will not be as satis-serted. The lever h acts upon a pivot in than in the ordinary way. The HUB MACHINE can be attached to the morticing machine, and the whole will not occupy, when in use, a space of over four feet by six in the shop, for the workman and his materials. We are un-authorised, yet take the liberty of referring to the following gentlemen, who have machines in use, and who will probably give an opinion in relation to them: Talbot & Perry, Prince st., used for mahogany doors Mr. Lasher, 16 Downing st., do do do do J. Green, do do chairs do Orange st., factory to many as one half hour's observa- DESCRIPTION. cross pieces or sills, with an upright post d, d, The slide, with a socket in the lower e, The CHISSEL, a small but very important part of the machine, It is made of foot upon the foot board, and pressing it down, the back end of the lever h also descends, and causes the chissel to perform on the rest l. It will be readily perceived its office upon the timber, which is laid up. that a powerful leverage is obtained by this arrangement, and that a rapid motion is easily produced with the foot, by which the chissel is driven into the timber, and drawn out again by the aid of the spring pole. The timber to be mortice is held in its place on the rest 1, until it receives a thrust from the chissel, when it is moved forward one eighth of an inch, by hand, or other wise, as the chissel rises, and falls again by |