Maintaining the Stability of Aeroplanes by Means of Gyroscopes T HERE are serious objections to the employment of gyroscopes for maintaining the stability of aeroplanes in the manner in which they are employed on the mono railway and in some experiments with nautical vessels. In order to utilize the peculiar property of the gyroscope on an aeroplane it must be used hS Capt. Lucas-Girardville has used it to operate special stabilizing devices in the manner of an auxiliary motor. The principle of this application and the experiments made by Capt. Lucas-Girardville are described in a' recent issue of La Nature, from which the following account is condensed: If a gyroscope, with its axis of rotation initially in the line OZ (lig. 1), its pivot at the point 0, and '8ntirely free to oscillate in all directions about this point, is acted on by a force which tends to turn the axis O!f rotation toward OY, the axis will resist the effort and will move toward OX, oscillating slightly to each side of the plane ZOX. This oscillation is called nutation. The value of the nutation il inversely proportional to the vis viva of rotation, and is therefore negligible for great angular velocities Fig. I.-Principle of the gyroscope. G, gyroscope; OX, OY, OZ, aXl'S of l'ectallglllar co·onlinate8 ; PF, deviating force,; Pp', prccession ; ab, llutation. of the gyroscope. The rotation of the gyroscope around OY toward OX is performed at a nearly constant rate. This movement, whkh is caned precession, is utilized for the operation of rudders by means of which the equilibrium of the aeroplane is maintained. The gyroscope is mounted in a carter which turns on two trunnions about an axis perpendicular to the axis of rotation. The line of the trunnions is parallel to the direction in which stabilization is sought. For example, if the line of the trunnions is parallel with the line of fligM, any tendency of the aeroplana to pitch or rear will be counteraded by an elevating rudder operated by the reaction of the gyroscope. The motion may be communicated to the rudder by a cord passing around a pulley attached to one of the trunnions (Fig. :). The efficiency of this system has been shown by preliminary experiments in which the gyroscope and the rudder were- mounted on an oscillating frame resembling the beam of a balance, the carter turning on an axis parallel to that of the beam (Fig. 3). The rudder was exposed to a uniform current of air produced by a blower, and the apparatus was adjusted so that it remained in equilibrium. In these condi- Fig. 2. -Gyroscope driven by flexible transmission from the motor. tions, if one end of the balance was depressed by the addition of a small weight or by touching it with the finger, the gyroscope, by means of a movement of precession about the axis of the carter, acted upon the rudder in a manner fO that the pressure of the current Qf air upon the rudder restored the equilibrium. The apparatus was found to be so exceedingly sensitive that it was necessary to damp the osciHations by means of a plunger and a cylinder flled with water. Experiments pe]formed with aeroplane models showed that even with only 130 square feet of sustaining surface the rea.ion of the air upon the aeroplane made the hydraulic brake unnecessary. It was demonstrated that in free flight an aeroplane AB, beam ; C, 8upport; D, gyroscope ; tt, trnnnions ; E, rudder ; MN, shaft of rudd,·r ; S, blower; P, hydraulic brake. would not oscillate appreciably under the action of the gyroscopic governor. The gyroscopic governors always operated in the proper direction with sufficient energy to restore the equilibrium whether the equilibrium was disturbed by changing the distribution of the load, or by employing irregular currents of air. Capt. Lucas-Girardville is now engaged in constructing and adjusting, at the Military Aviation Park at Vincennes, an aeroplane equipped with gyroscopic stabilizers. In t1is apparatus a large bearing surface of .nearly 1,100 Equare feet has ben combined with remarkable strength by means of a special constru,-tion. The main frame is a vertical pyramid of bamboo, which forms the central support of a great cIrcle made of steel tubes, attached to the frame by means oj' three systems of radiating steel 'ires (Fig. 4). This apparatus, which closely resembles an immense bicycle wheel 23 feet in diameter, is very strong and rigid. At two opposite points of the circumferenc8 are attached two projections which resemble the wings of an ordinary monoplane. The large circle and the two wings, covered with can vas, constitute the upper plane of a biplane, of which the lower plane is formed of a much smaller rectangular surface, the width of which eXceeds its length (Figs. 5 and 6). Two 70 horse-power Gnome motors of the new type are employed, placed in front of and behind the aeroplane in the line.of motion. These two motors, which are independent of each other, rotate in opposite directions, in Drder to eliminate gyrostatic action in turning. One motor drives a right-handed, the other a left-handed screw propeller. Hence the two motors, with their propellers, assist each other, and if one breaks down the other allows the fall of the machine to be retarded and made more gentle. The longitudinal stability of the apparatus is maintained by means of gyroscopes. In the first experiments the gyroscopes were driven by the motor by means of flexible transmissions and friction rollers, but this arrangement has been replaced by an aerodynamic system, in which the energy consumed by the gyroscopes is furnished by a small auxiliary propeller exposed to the wind produced by the main propellers. The gyroscopes rotate at enormous speed, performing about 6,000 rotations per minute. As they are in-tended to assure longitudinal stability, they are EO arranged that their movement of precession is performed about an axis ]aral l e l to the course of the aeroplane. In these conditions, when the I.achine tends to pitch or rear, the axis of the gyroscope turns to right or left and operates a rudder which res-tores the equilibrium. No attempt is made to supersede the human pilot in the control of the elevating rudders. The object, is simply to correct temporary instability or a mistake made by the pilot. By employing two gyroscopes both longitudinal and lateral stability can thus be assured to a certain extent. One gyroscope, with its axis of precession longitudinal, would control auxiliary elevating ruddel'S, while the other, with its axis of precession horizontal and perpendicular to the line of flight, would move ailerons or warp the principal planes. In this application Df the gyroscope to maintaining the stability of aeroplanes, it must be remembered that the gyroscope acts indirectly by operating moving parts, the effect of which can be increased, diminished, or annihilated at will by the pilot, by means of similar organs under his own control. The gyroscopes do not xert any direct influence upon the aeroplane, because they are not rigidly attached to it. The problem, indeed, is very different from that of the mono railway, in which it is required merely to prevent the car from falling over sidewise, while the rail maintains longitudinal stability by presenting a line of support which prevents the vehicle from pitch- ing or rearing. A gyroscope, rigidly attached to the car, prevents the lateral overthrow O'f the vehicle by endeavoring to perform a movement of precession in a perpendicular direction, which is prevented by the presence of the rail. In a freely flying aeroplanf such an apparatus would cause the vehicle to capsize. Lupus and Its Treatment AMONG the bacterial diseases of the skin, lupus is characterized by its extraordinary prevalence and the production of very deep lesions, which permanently disfigure so many faces. In the scientific department of the Dresden International Hygiene Exposition the ravages of lupus are illustrated by a series of wax models which, according to Hygieia, show the social and economic importance of the diseases more convincingly than words could do. According to the statistics of the German Health Bureau, 11,354 cases of lupus have been treated by German physicians since November, 1908. More than two-thirds of the patients were women. Lupus is treated in various ways. Volkmann's method consists in scraping the affected parts with a sharp spoon; Thiersch employs excision and transpJ.antation; while Hollaender recommends treatment with hot air and with Roentgen and radium rays. The tuberculin treatment Df K;ch and Finsen's light pp, automatic elevating rudder; P, elevating rudder operated by pilot; II, nutomatic steerin g rudders ; LL, steering rndder8 operated by pilot; gg\ gyroscopes ; D, steering wheel. cure are the most successful methods yet known. Finsen's celebrated institute was Dpened in Copenhagen in 1907. The great advantages of the Finsen method over others are that it is almost entirely painless and leaves no scars, except in places where the skin has already been destroyed. The apparatus employed by Finsen consists of a very powerful electric arc lamp of 30,000 to 40,000 candle-power, the raYs Df which are concentrated by quartz lenses. The radian'.; heat is largely absorbe(l bY a water cooltag device. As experiment has shown that the effective July «*, 911 SCIENTIFIC AMERICAN 83 rays are absorbed by the blood, and pressure is applied to keep blood from the surface. A hollow quartz lens, traversed by a continuous stream of cold water, is pressed firmly upon the diseased skin. The patient and the physician and attendants wear dark glasses to protect their eyes from the b:inding light. Although the Finsen method is very successful, it suffers from the defect of requiring a long course of treatment which, in extensive development of the disease, may occupy many months, as only a fraction of a square inch can be treated each day. A great advantage in this respect is possessed by Koch's tuberculin treatment, which rapidly dries up the pustules and checks the disease no matter how great its extent. The principle of the tuberculin treatment is the formation of protective bodies which kilI the bacteria in the skin. The progress in the treatment of tuberculosis of the lungs has recently led to a new endeavor to combat lupus. Despite the progress that has been made, proper care for the unfortunate patients, whose disfigurement makes Ufe a burden to them, demands the establishment of homes where they can find shelter and treatment. These homes could be partly supported by the work of the patients, according to their respective abilities. The Great Waterfalls of the World in Their Relation to Industry and Conservation THE waterfalls of the earth have become the subject of a conflict which is yearly increasing in violence. The lovers of nature wish to preserve the waterfalls in their original condition as far as possible for all time, while the engineers and industrial promoters seek to exploit them as sources of cheap power for electro-technical purposes. The accomplishment of this object on a large scale necessarily involves tne total destruction or serious injury of the waterfalls, regarded as picturesque additions to the landscapes. It is only within recent years that waterfalls have been considered from the commercial point of view, but since it has been recognized that the energy of flowing water in very many cases furnishes a cheap and almost inexhaustible substitute for coal, which is yearly becoming more cOftly and more largely consumed, the great waterfalls which, as impediments to internal navigation, have hitherto been worse than worthless from the viewpoint of social economy, have suddenly become objects of very great value. The falling water drives the turbines of electrical power stations, producing electric light and power which, in many cases, is transmitted over hundrel and even thousands of miles. The war over the waterfalls whIch is now being waged by the friends of nature and the promoters of industry is likely soon to increase greatly in bitterness, for many celebrated faUs have already been destroyed, or have at least suffered serious rsthetic injury, from the establishment of power stations. The famous Falls of the Rhine, at Schaffhausen, are at present the subject of heated controversy. Several power stations already stand on their banks and sap their life blood. The Swiss government, however, takes care to preserve a sufficiently large volume of water to maintain the character of the falls as a notable spectacle and an attraction for tourists. A still more bitter strife has been engendered in America by the question of the preservation or destruction of the Falls of Niagara. These famous falls have already narrowly escaped entire absorption in the pipes of power stations and very energetic action on the part of lawmakers, hath in the United States and in Canada, has been required to keep intact from industrial invasion and preserve, in its original beauty, at least a remnant of this great wonder of the world. Another North American waterfall which, as the highest fall in the whole world, especially deserves preservation as a natural monument, is apparently assured against destruction for all time. This is the Yosemite Fall in California, which makes, a descent of 2,600 feet in three successive stages. As the whole Yosemite Valley, which was not ciscovered until 1851, was made a national park in 1864, the Falls of the Yosemite are under governmental protection and their pristine beauty can never be marred by the establishment of any power station. There is a popular but erroneous impression, says Dr. Richard Herring in an article which is here reproduced from Ueber Land, und Meer, that the Falls of Niagara are the greatest in the world, and even those more enlightened persons who know that the Victoria Falls of the Zambesi River in Africa ar” twice as broad and more than twice as high as those of Niagara, almost invariably assign to Niagara the second rank among the great waterfalls of the earth. Even this is an error, for South America possesses a waterfall which exceeds Niagara both in width and in height and is actually the second largest waterfall in the world. This little known waterfall is that of the Iguassu River, a tributary of the Parana, and like Niagara it is situated at the boundary of two States, each of which owns half of it. The total water power of the Iguassu Fall, which is 213 feet high and nearly two miles wide, is estimated as about fourteen miilion horse-power. This is approximately equal to the aggregate water power of all Scandinavia, which is so rich in waterfalls, or about ten times the total water power of Germany. The temptation to exploit this gre3Jt, inexhaustible, never-freezing stream as a source· of power for industrial purposes may easily be imagined. At present such exploitation is quire impossible, as tne Iguassu Fall is too far from the beaten tracks of commerce to make it profitable to establish any electrical power station, but it wiII probably not be long before these falls will be threatened with the fate of Niagara. This undesirable possibility has been foreseen by the interested States, Brazil and Argentina, which. have already begun negotiations designed to protect the falls. The largest of the earth's waterfalls, the Victoria Falls of the Zambesi River, in Rhodesia, which are 386 feet high and more than a mile wide, and which were discovered by Livingstone in 1855, have also become the subject of a compromise between the coniding demands of the lovers of nature and the promoters of industry. The water power of these falls is estimated to be fully thirty-five miIIion horse-power, two and one-half times that of the Iguassu, and five times that of Niagara. By way of comparison, it should be noted that the aggregate water power of the whole of Europe cannot greatly exceed thirty-five million horse-power. It is certainly possIble to derive a few miIIion horse-power from this great faU without appreciably detracting from its majestic beauty. The demands which are made at present are still more modest. The Victoria Falls Power Company ask for only 150,000 horse-power, less than 1/200 part of the whole, and the plans for the future development of the station involve no danger of the annihilation of the falls. The British government and the colonists know very well that the Victoria Falls, which since 1905 have been easily reached by the Cape-to-Cairo Railway, which crosses the Zambesi immediately in front of the principal fall, wiII certainly bring as much money into the country by attracting tourists as by producing electrical power. There is no other waterfall in the world which is at all comparable in greatness with the Zambesi, Iguassu, or the Niagara. Asia, notwithstanding its colossal mountain ranges, is comparatively poor in large waterfalls which are found most abundantly in Africa and North America. The largest AfrIcan streams, especially, are interrupted by many falls of considerable height. The Congo has several high falls which, owing to the great volume of the river (about sixteen times that of the Nile), may be counted among the most important sources of water power on earth. The Stanley Falls, in the middle reach of the river, consist of seven successive falls, of a total height of 164 feet and a width of nearly 4,000 feet, and offer an exceedingly rich source of power which proba,bly will soon be exploited. Still more important is the total water power which the Congo develops in the non-navigable section extending from its mouth to Stanley Pool. Here the river, confined in a channel only a few hundred yards wide, and with a depth of water of nearly 300 feet, flows with a velocity of 48 feet per second so that at every point of the stream 25,000 to 30,000 cubic meters, or about a million cubic feet, of water are hurled along with irresistible. force, while thirty-two rapids and waterfalls lower the level of the stream by 820 feet in a stretch of 170 miles. The lower Nile in Egypt possesses a series of rapids, the celebrated Cataracts of the Nile, but no waterfall in the strIct sense of the word. True waterfaHs occur on the upper Nile, the most beautiful of them at the point where the stream issues from Lake Victoria Nyanza. ThIS Ripon fall is only a few yards in height, but the volume of water is so great that it presents a magnificent spee,tacle. Comparatively few persons know which is the highest waterfall in Europe. The most voluminous of European waterfalls, strictly so called, are the Rhine Falls at Schaffhausen, but the highest are the Rjukan Falls of the Maan-Elf River, in the Norwegian province of Telemarken. The principal fall is 800 feet high and the total height of the two chief falls with the intervening rapids amounts to 1,837 feet, while the average flow of water is 50 cubic meters, or 1,760 cubic feet, per second. The largest water power station yet prOjected is here being developed by the Badische Aniln und Sodafabrik, in conjunction with other firms, for the fixation of atmospheric nitrogen. The Rjukan Falls, with their total energy of 250,000 harse-power, are already things of the past, for they have been irrevocably perverted to industrial uses. A similar fate threatens other small Norwegian falls, but Norway is so rich in waterfalls that it can well spare a few. In Sweden, likewise, the Falls of Trollhatta, the most celebrated of all Scandinavian waterfalls, have been almost entirely annihilated as objects of natural beauty. Nearly all of their water is now employed for the production of electricity. The government itself has recently established here a power station with a capacity of 40,000 horse-power. This, now the largest water power station in Europe, will soon be surpassed, however, by the station at Rjukan in Norway and 'y a still larger station in the north of Sweden, which will serve for the operation of the Lofoden Railway. The Porjus Fall, at which this last-mentioned station will be placed, is only one fall, or rather rapid, of a long series formed by the Lule-Elf, near its source in the lake region of Lapland. The largest and most beautiful of these falls is the celebrated HaIsprang, which forms the subject of many legends. The Porjus power station is expected to reach 'Completion in 1914 and to develop soon afterward about 80,000 horsepower, yet the wild beauty of the Porjus Fall will be little affected, as it is estimated that its total water power in summer, after its sources of supply have been regulated, will be about 300,000 horse-power. In the Por:us Rapid the river descends 164 feet in about 2 miles. The Harsprang is also half waterfall and half rapid and accomplishes a descent of 244 feet in 1' miles. The Harsprang would therefore yield more power than the Porjus, but it is to remain untouched for the present, and it is to be hoped that it will be forever preserved as a natural monument. !Sweden, with its great wealth in water power, can well afford such a luxury. Even little Finland is endeavoring to preserve natural beauty and has decided to keep her greatest waterfall in its original condition as a natural monument, and to allow no large power station to be erected on its banks. This fall is the celebrated Imatra Fall of the Wuoxen River. The total descent is only 66 feet in two miles, but the volume is very great and the depth considerable, while the width of the stream contracts from 570 to 150 feet in the course of the falls. Some Engineering and Economic Results of the Commercial Motor Vehicle. THE Engineering N eW8 recently expressed the opinion that “The commereial motor vehicle must be able to show an all-around saving in the cost of doing a given task before it can expect to find favor as compared with the horse-drawn vehicle." Further, it stla,tes, the motor-vebide must make a very substantia.[ saving over the simple, cheap horse-drawn vehide in order to win success. Any motor-vehicle equipmont is going to require a large investment compared with horses and wagons, and the purchaser must be shown a good profit on this investment after the items of depreciation and repairs are provided for. "The average merchant, or manufacturer or contractor is not going to make a large investment in motor trucks or motor delivery wagons unless these vehicles can ea,rn a good deal ma-re than six per cent net on their first cost. Most concerns are borrowing money at that ,rate to use in their business." At the present time however experience accumulated from many sources appears to show that there are commercial motor vehi(jes now on the markel which can, under favorable circumstances, show a large saving over the cost of working with horse drawn vehicles. The great advantage of the motor vehicle is that it can run at higher speed and carry heavier loads than any vehiclE drawn by horses. Every engineer who has made an analytical study of the cost of wagon traffic knows that one of the largest items in the ton mile cost of freight haulage over common roads is the wages of the driver. It is an interesting fact that the lowest ton-mile costs for haulage by wagon over common roads in the United States are not made over the improved raads of the East. They are made in remote districts of the West, still beyond the reach of railways, where goods have to be hauled long distances over the crudest sort of highways and where the volume of traffic is such that teams of eight or a dozen or more mules are used to a load and one driver manages a load of several tons. "It will be apparent from this that one of the most hopeful fields for the use of motor trucks is in any industry where the volume of traffic permits heavy loading and long hauls. The motor vehicle will make a better economic showing in heavy trucking, for example, than in light delivery wagon service. In the latter service, again, the advantage will be much greater if run on a suburban and country route, where distances are long and stops are few, than on a city route, where a small area is covered." 84 SCIENTIFIC AMERICAN July 22, 1911 [The EdiTor of Handy Man's Workshop will be glad to receive any stlggestions for tlds department and will pay for them, promptly, if available.] A Simple Turnbuckle By William Grotzinger. ASIMPLE turnbuckle which I devised and used on my monoplane glider can be easily made as follows: Take the spokes and nuts out of an old bicycle Turnbuckle made of a bicycle spoke. wheel. Twist the wire at the unthreaded end, so as to form a loop to receive one end of the bracing wires. For the other end, cut a strip from a piece of sheet iron, 3 inches long and % inch wide, punch a hole in the center to receive the threaded end of the wire. Punch a small hole at each end of the strip to receive the other end of the bracing wires. Now bend the strip as shown in the illEstration, and put the nut in place. You will then have a small, neat, strong turnbuckle, which can be used for many purposes. Adz-tightener By W. A. Lane AT its best, an adz is a rather dangerous tool to use, and to have it work loose is nearly certain to end in disaster. A tightener as shown here is not expensive, can be put on any adz, and will last as Jong as the adz itself. On the upper edge of the head drill a hole and tap for a %-inch set-screw as Adz-tightener. shown in the drawing. Have the square head on the set-screw flattened like a thumb screw, so that you can tighten or loosen it with the claws of your hammer. Next, make a thin strip of iron the width and length of the upper side of the eye. The set-screw bears on this iron strip and makes the pressure 011 the handle even. Turning Ball Joints to Gage By C. G. IN Handy Man's Workshop of April 1st, there was a description of a method of machining ball and socket joints. The writer is of the opinion that the tools used in the method described would be apt to Device for turning balls to gage. become dull in a comparatively shol t time, and then could not be sharpened without altering the gage. A friend of the writer recently designed tre device shown in the accompanying sketch, which overcomes the difficulty. The cutting tool used is shown in perspective in Fig. 2. It will be observed that it consists of a bar with a channel in the upper surface which is of such shape that when the bar is cut off at an angle of 45 degrees, a cutting edge will be formed that will be a true semicircle. The tool is used in a device somewhat similar to a pair of pliers, as indicated in Fig. 1. In one of the jaws of tho pliers is a bearing block with a pyramidal socket to receive the baU, while the cutting tool is mounted at an angle of 45 degrees in the other jaws of the pliers, with its cutting edge oentrally disposed under the bearing block. With the shank of the ball end secured in the chuck of a lathe, the pliers are placed over the ball in the pOSition indicated, and then the handles are pressed together until stopped by an adjusting screw, the tool in the meantime cutting the ball to standard gage. When the tool wears down, as will be the case after a few balls have been turned, it may readily be sharpened, provided the same angle is always preserved at the cutting edge. An Improvised Bobbin Winder By Henry H. Riggs H AVING wasted much time winding small bobbins by hand for Iaek of a lathe, the last time I had to wind one it occurred to me to make use of a common drill brace, which proved so satisfactory as a bobbin winder that I pass the idea on to other amateur electricians whose outfit is limited as mine is. The method is shown in the photograph. A drill shank or any bit of heavy wire will answer as a spindle to mount the spool on. If it does not fit the hole in the spool, wrap it with paper till it does, snugly. Improvised bobbin winder. If a vise is not available, the brace can be clamped to the edge of the bench with a screw or two while the winding is being done. A large spool of heavy wire can better be wound with a common carpenter's auger brace. The spindle on which the spool is slipped should be longer than the spool. The end is then supported by inserting it in a hole bored in the edge of the bench, while the butt end of the brace is supported in its traditional place in the “pit of the stomach.” This leaves both hands free for winding. Home-made Anchors By Albert F. Bishop HERE are two ideas that may be useful to the handy man who owns a boat, but doesn't own a suitable anchor. One of the illustrations shows an anchor of the conventional form, but made of wood and stone. A piece of wood with a natural bend is used for the fluke piece. The ends must be pointed and two holes must be bored through it, about 4% inches apart, to receive two sticks of very hard wood. Each stick should have a knob on one end to keep it from drawing through the fluke piece. A stone should be placed between the sticks which may be sprung so as to em- Anchor for a house boat. brace the stone tightly. The sticks should then be weIl seized close to the stone and also at the upper ends. Anchor ropes are usuaIly fastened to the fluke piece and thence pass up to the ring or loop, being seized there with a smaIl cord. When pulling up the anchor this cord will break if the anchor is caught in the rocks. The rope will then capsize the a nchor and probably release it. The writer saw thjs anchor on the hank of a river and thought it a very clever idea. The holding qualities looked very good. The other anchor illustrated here is adapted particularly for houseboats. A cross of wood is made and holes are bored near the ends. A square weight is laid on the cross, and bows of hard wood are inserted in the holes and are drawn down tightly on the stom, The ends of the bows are well secured by means of hard-wood wedges. The rope is fastened to the cross and seized with a cord to the junction of the bows. This anchor was used hy the captain of a small craft. He felt very secure when anchored with this homemade device. Making a Wooden Tube By W. D. Graves IN the days when iron pipe was more expensive than It now IS, and wood cheaper, it was a common practice to bore logs lengthwise and to use them for carrying water underground, often for long distances. It was an easy matter to bore accurately in the center of logs hecause, in the kind of wood chlsen for the purpose, a small open or pithy “heart” extended through it. This was vel'y small, usually but Uttle larger than a pin, but it was sufficient; for the worm of a bit found it to be “the line of least resistance” and would follow it. While this sort of wooden pipe is rarely to be desired, nowadays, it is sometimes desirable to have a wooden tube and to Imow how to make H. By making it in two parts one may arra n ge to guide the bit in much the same manner as did the old time aqueduct makers, and even more accurately. These parts should be gotten out as shown in end view in the drawing, the two inserted tongues, a. (, serving to hold them relatively in place and to make the joint tight. Along what is intended for the center of the hole a deep gage mark is made, and, with a ¦corner chisel or other tool,-a small triangular section is removed for the whole length so that when the two parts are clamped together a small square hole will extend through where the center of the final hole is to be. The size this “pilot” hole should be depends upon the size of the bit or auger to be used. For a large auger it will not need to be more thaI an eighth of an inch square, and for a small bit the gag8 mark alone will often be found sufficient. H must be large enough so that the point of the worm will enter it, but small enough so that the bit will be firmly guided and drawn forward. When boring the paris must be very firmly held together and the bit must be drawn out as often as the pod fills with shavings. For the latter reason it is advantageous to have a bit with as long a pod as u Blank for a wooden tube and double crank for auger. is available. The shank af the bit is best lengthened by welding a steel rod to it. For turning it a common brace may be used; but if much work of this sort is to be done, it will be found to be accelerated by having the end of the rod bent into a double crank, like that commonly used on “ship augers,” as illustrated. This is operated by taking hold at A and B with each hand. It requires a Uttle practice to enable one to turn the cranks thus without making the bit wabble considerably; but as soon as one gets the knack he can do the work much faster than with a lrace, and much mQre easily,