RIFLE MAKING

In The Great Smokies

BY ARTHUR ISAAC KENDALL,
PROFESSOR EMERITUS OF BACTERIOLOGICAL RESEARCH,
NORTHWESTERN UNIVERSITY SCHOOL OF MEDICINE

The rifled gun, the American rifle¹, or as it frequently is called, the Kentucky rifle, which in the hands of the sturdy settlers turned the tide against the Indians, was evolved largely in America.

The idea of rifling a barrel to make it shoot truer and harder was not new, to be sure. About 1550, Gaspard Zeller or Zollner, of Nuremberg, Germany, cut spiral grooves in the barrels of guns; but rifling in its perfected state is almost entirely an American development, a highly important step in the generation of the rifle which was designed specially to meet the conditions that existed in the wilds of the east central part of the United States. Indeed, this extraordinary arm evolved gradually to its highly perfected state in response to the demands of the hunters who used them, and the chief credit for the mechanical perfection of the American rifle apparently should go to the highly skilled rifle-makers of Lancaster County, Pennsylvania, who incorporated patiently, step by step, the suggestions of the pioneers who used it. The several characteristics which a rifle satisfactory for frontier use should possess were: (1), sturdiness combined with lightness and mobility; (2), rapidity in loading; (3), economy of ammunition; (4), accuracy and hard shooting for reasonable distances, and, (5), a report of small volume.

Preceding the perfection of the rifle, several accessory factors, each important in itself, had to be developed. Even-burning, uniform-grained, high grade powder had to be evolved. A patch, to facilitate the loading of the rifle and accuracy of delivery of the bullet was necessary; a device to cut the precise rifling in the barrel to give to the spherical bullet its spinning flight had to be invented, and required finally was perfection of the firing mechanism without which the rifled gun would be ineffective.

Primitive guns were merely tubes of iron closed at one end and fired by means of a burning stick applied to a touchhole. They were clumsy, inaccurate and ineffective. Next came the match lock, the essential feature of which was a movable arm capable of being raised and lowered, pivoted at one end on the side of the gun, and containing on the free end a slow burning fuse that was lowered by a simple mechanism into a small pan of powder connecting through the touchhole with the main charge in the barrel. The match lock was portable, capable of being aimed, but uncertain in wet or windy weather.

A later improvement in the development of the gun was the wheel lock, a device whereby a wheel was made to rotate by a spring mechanism in such manner that flint striking on steel, threw a shower of sparks into the powder pan and thereby set off the charge in the barrel. The wheel lock was heavier than the match lock but rather more certain in its firing ability.

Next came the snap haunce, a somewhat primitive progenitor of the flint lock, which was the method of ignition of the true early American rifle. The flint lock consists of three parts essentially--a hammer or cock having in its jaws a sharp flint, a frizzen or steel against which the flint is thrown when the trigger is pulled, and immediately below the frizzen, a pan containing powder to be ignited by the sparks from the fall of the flint. The fire in the pan is communicated through a touchhole to the main charge of powder in the barrel of the gun.

The final improvement in the fabrication of muzzle loading rifles was the introduction of the percussion cap. With the perfection of the percussion lock guns the art of rifle making by frontiersmen, mountaineers, and others living in the more remote areas of America came to an end. The machinery required to manufacture breech loading rifles with steel barrels to withstand the high velocities attained by smokeless powder was beyond their simple tools and primitive equipment.

These several essential details of the American rifle were evolved and nearly perfected before 1740, and the pioneer gunsmiths of the states of Kentucky and Tennessee, many of them coming from the Carolinas and Virginia, brought the art of rifle making with them. This art was handed down from father to son, together with the tools and other equipment, secrets of tempering and case hardening and certain accessory details which were kept jealously within the family. Certain of these details are of value both as a means of identification and as milestones in the ultimate development of the rifled gun.

The American rifle was often ornamented in a variety of ways with silver sights, silver inlays in the stock, and beautifully tooled and engraved trigger guards and patch boxes. The rifles made by the gunsmiths of the Great Smoky Mountains on the contrary were usually devoid of ornamentation. The mountain people, cut off from communication with the outside, had to rely upon their own resources and their hard lives were reflected in the simplicity and unostentation of the rifles which were made by them. Yet, in spite of their austere appearance, these rifles possessed those essential characteristics of a satisfactory and formidable weapon. They were sturdy but graceful, economical of ammunition, capable of rapid fire, accurate, and hard shooting.

Turning a rifling guide on a primitive lathe (left), and cutting out its spiral grooves

Almost all the material necessary for the fabrication of the rifles was ready at hand in the Smoky Mountains---pure iron from the Cumberland Mountains for barrels, locks and triggers; seasoned curly maple or walnut from the forests for stocks; hickory for ramrods from the standing timber; and lead from local mines for bullets. The small amount of steel required for springs was retrieved carefully from worn out files, saws, or other discarded agricultural or mechanical implements.

The essentials of a rifle are: (1), the barrel; (2), the lock and trigger, which in the American rifle are entirely separate mechanisms; (3), the stock; and, (4), the smaller parts---sights, butt plate, thimbles for the ramrod, and brass or iron for the patch box and trigger guard.

The barrel was made from pure iron in one of three ways.

The first method: A solid bar of iron² of the required length and diameter (usually four feet long, octagonal, and from an inch to an inch and one quarter in diameter) was forged and shaped on anvil and grind stone. It was carefully bored longitudinally in a hand driven lathe.

The second method: Two halves that eventually would be a barrel, each about four feet long, an inch to an inch and a quarter wide, and about half an inch thick, were channeled with a swage on one longitudinal side to produce a semi-circular groove the entire length of the prospective barrel. Then the two halves were welded together, making a complete barrel with a hole through it.

The third method: A strip of iron some four inches wide, of the proper length and the thickness of the barrel wall was heated a few inches at a time and laboriously welded spirally about a steel mandril until the desired length was attained.

After the rifle barrel was made by any one of the three methods just described, the next step was to clean the bore and straighten the barrel. The bore was cleaned by means of a long bit, a rod of iron some four feet in length, having welded on one end a steel cutter, oblong in cross diameter, and with four sharp cutting edges, each some 10 inches in length. Ordinarily the cutting surface of a long bit is about a quarter of an inch in the lesser diameter and 3/8 of an inch in the greater, but the size depends largely upon the diameter of the bore of the gun. Running the length of one cutting surface of the long bit is a thin piece of hickory fastened on the narrower side in such manner that a thin shin can be placed underneath the middle of it. The cutting edges of the bit thus are kept in contact with the metal of the barrel, the slight offset produced by the hickory stick giving clearance for the shavings. The bit was turned in the barrel by hand or with a brace and gradually worked the length of the barrel and back again until it would cut no more. Then the shim was made a bit thicker in order to make the cutting edges of the bit press more heavily against the wall of the barrel, and the process repeated. The final result of dressing out with the long bit was a mirror bright hole through the barrel of the rifle, isodiametric and true.

Next the barrel had to be straightened. Frequently, during the several processes involved in the fabrication of the barrel as outlined, it became a bit bent. A good optical principle was relied upon to determine whether the barrel was straight. A fine linen thread, freed from "furze" (as one gunsmith expressed it) was threaded through the barrel and kept taut by a hickory rod, to which the projecting ends of the thread was tied. When the thread thus stretched inside the barrel, it was held up, preferably to the north, and pointed toward a white cloud. Looking through the barrel it readily could be seen whether the string touched at every point. If not, a few blows on the anvil, skilfully applied at the proper place, usually made the barrel true, The process was repeated if necessary. Obviously a crooked barrel would not make an accurately shooting rifle.

Complete assembly for rifling a gun, left to right: rifling guide, head block, rifling rod and barrel of rifle.

The next step was the rifling, the most important process of all. Although apparently complicated, it is in reality simple. First, a "rifling guide" is prepared. Ordinarily this is made from a round stick of timber two to three inches in diameter and some four and a half feet long. This is carefully turned to the requisite size in a lathe and then the circumference is divided accurately into five or seven equal parts³. A withe of pliant oak about one-quarter inch wide and some six feet long is then prepared. One end of the withe is fastened to the center of one end of the guide with a nail in such manner that it rotates freely.

Starting at one of the seven divisions, the withe is wrapped carefully around the wooden cylinder so that it makes exactly one symmetrical turn in the entire length. that is to say, one turn in approximately 48 inches.⁴

Dressing out with a dressing stick

A pencil mark is then made along the side of the withe and this process is repeated for each one of the remaiming divisions. When this step is complete there will be seven spiral marks (or five), equally spaced and symmetrical around the wooden cylinder and these indicate the twist or speed of the rifling. With each one of these seven symmetrical spiral marks successively as a guide, a second spiral line about a quarter of an inch away is drawn exactly parallel to each of the seven original sets of spiral markings. The wood between each of these seven paired parallel lines is removed carefully to a depth of perhaps a half-inch, leaving as the final stage in the preparation of the guide a wooden cylinder having a set of seven symmetrical spiral bands each turning once in about 48 inches. At this stage the cylinder looks much like a long wooden threaded bolt. If the spiral or twist of the rifles were much sharper than one turn in 48 inches, the weapon would be ineffective. The bullet, as the mountain men say, "would strip its patch" at the higher speed of rotation. Consequently the majority of the rifles in the Great Smoky Mountains have a spin or twist of approximately one turn in 48 inches.⁵

After the rifling guide is made as described, a "head block" is prepared. It is a piece of hard wood about an inch thick and five or six inches wide, having cut in it a hole which is the exact reverse of a cross-section of the rifling guide with its spiral bands. In other words, the head block bears the same relation to the rifle guide as a nut does to a bolt. Ordinarily the bearing surfaces in the head block were lined with leather which, when well greased, allow the ridges of the rifle guide to slip through with ease.

The rifling guide and head block are mounted on a stout timber long enough to hold both the barrel of the rifle and the full length of the rifle guide in one straight line. This timber is anchored firmly so that it is immovable, and the block is fastened permanently to it near one end in such manner that when the rifle guide is threaded through it, the latter can be moved back and forth its full length without undue vibration, imparting meanwhile the proper rotation to the rifling tool. The barrel is mounted in the exact axis of the guide, so aligned that the rifling tool, which will be described, will pass through the barrel in response to a back and forth motion of the rifling guide. A twist corresponding to the twist of the guide is imparted to the rifling tool, which in turn cuts the grooves or rifles in the barrel.

The rifling tool consists of a steel rod somewhat more than four feet in length and of a diameter a little less than the bore of the rifle. One end of this rod is fastened firmly to a chuck or slot in the end of the guide so that it will turn coincidentally with the guide. The other end, for a distance of some four inches, has cast upon it a lead block of exactly the bore of the rifle. This is dome by winding a string about the end of the rifling rod to form a narrow band equal to the bore of the rifle. Then the rifling rod is inserted into the end of the rifling barrel for a distance of some four inches. Melted lead is poured around the rifling rod. The lead is kept from running down the barrel by the string barrier. When the lead is hard the rod is removed from the rifle. It will be seen that there is molded on the end of the rifling rod a lead plug of exactly barrel diameter.

The next step is to seat the "saw" in the lead plug. The saw is pictured most easily perhaps by visualizing a small section of a hack saw blade having some six or eight teeth. This saw is inserted in the lead plug in such manner that the teeth project slightly from the side, giving them only a limited clearance or cutting surface. It is necessary to have the long axis of the saw align precisely with the line of twist of the rifling. This is done by first threading the rifle guide into the head block; than the rifling rod is fastened by the clamp to the rifle guide and the other end of the rifling rod with its lead plug is pushed through the barrel of the rifle until about two inches project on the far side. Then, by means of a steel tool, whose width is exactly that of the width of the "saw", a longitudinal groove is cut in the lead plug. This is done by moving the lead plug back and forth by alternately pushing and pulling on the guide for the proper length, and deep enough so that the saw will be inset far enough to give rigidity. Ordinarily this depth is about one-sixteenth to one-eighth of an inch.

After the saw is put into its groove, with the teeth projecting but little, it is ready for use. The rifling guide is threaded through the head block, one end of the rifling rod is inserted in the end of the guide, and the other end carrying the lead plug and its saw, well lubricated with unsalted tallow, is inserted in the barrel. Drawing the rifling guide back and forth through the head block imparts the proper spin to the saw for the entire length of the barrel, and a spiral groove is cut, turning one in about 48 inches.

When the saw has cut the groove as deeply as it can, the guide is withdrawn from the head block and inserted again, one groove to the right, and the process repeated until all seven parallel grooves successively have been cut out. Then the saw is removed from the plug and raised up by putting a strip of paper at the bottom of the groove under the saw. Then the entire process is repeated. Eventually, when the rifles are cut "ten to fourteen papers deep," there results a barrel having on its inside seven spiral grooves, the counterpart of the rifling guide in so far as twist is concerned, and deep enough to transmit a spin to the bullet when the rifle is fired.

Making the rifle stock

The newly rifled barrel has to be "dressed out" to smooth the rifles or grooves, and the ridges between these grooves, called the "lands". To perform this operation a "dressing stick" must be prepared. This is made upon a hickory rod somewhat less in diameter than the bore of the rifle. On one end of the hickory rod a lead plug is run in precisely the same manner as the original lead plug above described was run on the end of the rifling rod, the difference being, however, that this time the lead plug on the end of the dressing stick has the pattern of the rifles on it.

A saw corresponding to the original saw is inserted in the lead plug in exact alignment with one of the rifles and midway between the ends, and a second saw, the width of the lands, and in exact alignment with one of the lands, is inserted also. This dressing stick, well greased, is drawn back and forth through the barrel until the rifles and lands are smooth and evenly cut. Usually from a day to a day and a half was required to rifle and dress out a barrel in this manner.

Strictly speaking, these rifles had no caliber in the ordinary sense of the word. Usually, however, four kinds of rifles were made: one of about .35 caliber (0.35) inch, which was called a squirrel gun; one about .40 caliber, called a turkey rifle; one about .45 caliber, called a deer rifle; and one of approximately .50 caliber call ed a bear gun.

After firing from 80 to 150 rounds it was often necessary to redress a rifle, that is, to resharpen the edges of the rifles and clean the lands. The redressing was done in the manner indicated above by means of a dressing stick provided with both rifle and land saws; and naturally the bore became a little larger. It was usually necessary also to cut off an inch and a half or thereabout from the breech of a rifle that had been fired this number of rounds because at the point where the powder actually burns, the iron gradually becomes eroded and an enlarged chamber forms which eventually would cause the bullet to shed its patch. The shooting age of a mountain rifle can be guessed approximately, therefore, by the length of the barrel.

To finish the barrel after the rifling is complete, several more steps are necessary. A thread has to be cut in the breech and in this is screwed the iron breech block which closes the rear of the barrel. Usually the breech block is made with a tang from two to four or five inches long. One or two holes, drilled in the tang, provide entrance for screws which fasten the barrel securely to the stock. Next, if the rifle was a flint lock, a touchhole had to be bored in the side of the barrel about one-sixteenth of an inch in front of the breech block. If the rifle was one of the percussion type, a hole was drilled and threaded barely in front of the breech block in which was fitted the side tube carrying the nipple for the percussion cap. Along the barrel two or three metal tabs were brazed lengthwise through which holes were made. Metal pins were driven through these to fasten the barrel securely to the stock. The addition of front and rear sights completed the barrel.

The front sight was usually of the knife type and the notched, immovable rear sight set ahead of the breech block some six or seven inches. This gave a long sighting base which accounts in no small measure for the accuracy of these remarkable weapons.

Trigger and lock mechanisms were made next. If the rifle were a flint lock, the hammer or cock had a screw clamp or vise in it to hold the flint which was always set in a piece of thin leather. A hinged frizzen was made of steel upon which the descending flint would strike a glancing blow, throwing the frizzen forward and allowing the sparks to fall in the small pan which was in front of and below the hammer and directly opposite the touchhole. The lock or hammer for a percussion rifle was of the orthodox shape familiar to everyone. Usually the striking face of the lock was hollowed out a bit to fit over the cap and deflect any sparks.

Ordinarily the triggers were double, there being both a set trigger and a hair trigger, the former behind the latter. A small screw between the two regulated the tension, and therefore the lightness of pull of the hair trigger. To manipulate the firing mechanism of a percussion cap rifle, the triggers were set, that is, the hind trigger, "the hindmost one" as the mountain people say, was pulled until it clicked. This set the hair trigger. Then the hammer was raised and, with a cap on the nipple and the gun loaded, the arm was ready for firing. A light touch sufficed to release the trigger.

The pattern of the original Kentucky rifles was a little different from that adopted by the mountain people, although the amount of drop in each was quite conspicuous. The butt plate was deeply hollowed out, the curvature being relatively greater on the top side. The butt plate was made either of brass or of iron. The reason for hollowing out the butt plate was said to be that the marksman could hook the butt of the rifle in the crook of his right elbow and shoot crosswise of his body, it being believed that in this manner the person, especially if behind a tree, offered a smaller target to an enemy than would be the case if the rifle were shot straight ahead from the shoulder.

Each mountain rifle-maker had a pattern or template from which he marked off the shape of his stock. The stock usually was made from curly maple or walnut, although other woods sometimes were used. It was either a half stock, in which case a wooden or am iron rib was fastened beneath the barrel from the tip of the stock to the muzzle, or a full stock, with the wood extended to the muzzle. The thimbles for the ramrod were next put in place, the ramrod extending through the stock parallel to the barrel. All of the mountain rifles had a check piece on the left side of the stock, the pattern of which varied in accordance with the design of the different makers. Usually, however, the under side of the check piece was straight. This was used as a storage place to carry bees' wax or tallow. The pattern of the trigger guard was of individual design, some being quite ornate, others plain and simple.

The stock was finished with a hinged patch box on the right side extending from the butt plate forward, in some instances as much as six inches. The design and engraving of these patch boxes and workmanship of the hinged lid was often carefully done. Patch boxes were omitted from the later rifles made in the Great Smoky Mountains. Many of the rifles had a six-pointed star of German silver or iron on the top of the check piece.

Individual bullet molds were made for the rifles. Blanks for the two halves were beaten out of a piece of iron, hinged at the proper place with a rivet, and then the spherical cavity was cut by means of a "cherry". A cherry consists essentially of a sphere of steel the size of the bore of the rifle mounted through a slender shank to a bar of iron. The temper was drawn from such a sphere and the cutting edges, exactly like those of a dentist drill, were filed out laboriously. The cherry was heated and dropped into water (case hardened) which gave it an intensely hard surface. The halves of the bullet mold were opened, the cherry was rotated between the faces, either by hand or by a bit brace, and gradually a spherical cavity was ground out. As the cavity neared completion the narrow neck of the cherry cut a channel to the outside and this became the sprue through which melted lead was poured to make the bullet.

When a rifle was dressed out after a period of use, the bore became a trifle larger, and it was therefore necessary to enlarge the bullet mold to fit the new condition. Usually a mew cherry was required. Time was a secondary factor with the gunsmiths of the Great Smoky Mountains. To make a new cherry, a dressing stick or, indeed, any of the multitudinous pieces of equipment for a mountain rifle, was all in a long day's work.

The charge of powder for these rifles deserves a word of mention. The formula one reads in the stories of old-time hunters was to put the round bullet in the palm of the hand and pour out just enough powder to cover it. This was an extremely crude approximation and no good rifleman ever relied upon such a primitive procedure. Ordinarily the charge was arrived at by trial and error. One method was to spread a cloth sheet or several papers on the ground and then to mount the rifle in a horizontal position some six inches above the paper and parallel to it. Various charges of powder were tried until a charge was found which would leave only a few grains of unburned powder. Provided the bullet was always seated with the same pressure, this charge ordinarily was accurate within reasonable limits.

Another method was to set up a target the standard distance for the mountain rifles (60 steps or yards) and fire a series of test shots, varying carefully the amount of powder with each shot until an amount was arrived at which would give the maximum accuracy. Then a powder charger was made, usually from a tip of a deer horn with a slight lip on it, which, when level full, would hold the requisite amount of powder.

For the most accurate shooting, however, the mountain men of the more modern times often took cartridge shells with bottle necks, especially those of approximately .32 caliber, since by means of the constricted neck they could get a somewhat more accurate measure of powder than could be had through the use of the wide mouthed deer horn measure just described. Usually rather fine powder, FFg, was preferred for the smaller caliber rifles when it could be had. For bear guns FF was used ordinarily.

The sights on the mountain rifles were not adjustable and inasmuch as the rifles were sighted ordinarily for 60 yards, it was necessary to make some allowance in elevation for shots over and under this distance. In the target matches, which were serious occasions, specially designed targets were used if the range were materially more or distinctly less than 60 yards. If the range were greater than 60 yards, obviously with a standard charge of powder the ball would drop somewhat at the point of impact. For shorter distances the ball would strike higher. In order to compensate for this the targets were made in the following manner: The distance was measured. If the range exceeded 60 yards, a diamond was cut in the paper about five-eighths of an inch on a side with the axis vertical. Beneath the diamond at the proper distance a V-shaped piece was cut out, the point of the V being uppermost and in a true line with two points of the diamond above. The paper thus prepared was tacked over a piece of white, freshly planed board which had a blackened area corresponding approximately to the area covered by the diamond and the cut. If a board was moistened and some powder rubbed on it, a satisfactory dull black smear could be made which showed up conspicuously against the white of the paper. In firing, the objective was to place the ball at the apex of the V-shaped cut, and the rifle was sighted at the bottom of the diamond, the distance between the sighting point (the diamond) and the prospective hitting point (the V) being determined from experience. If, for example, at a range of 80 yards the ball dropped an inch below the striking point at 60 yards, then the aim point or diamond on the target would be an inch higher than the V-shaped point where it was hoped the bullet would strike. For distances under 60 yards the target was reversed, the V being above the sighting diamond.

The rifle was loaded in this way: The barrel being clean, powder was taken carefully from the powder horn and poured into the charger. It is to be noted here that horn is a peculiarly good substance in which to store powder. It is waterproof, and therefore the horns of cattle were much sought for for this purpose. Inasmuch as the powder horns should curve around the body and not away from it, it was necessary to select the proper (left) horn of the animal to get this curvature. The stopper of the powder horn was always of leather.

After the charge of powder was removed from the powder horn, the stopper was replaced and the charge poured into the vertically held barrel. The rifle was tipped, so that the tube side was down, and given a few vigorous taps with the hand to force the powder into the tube and nipple. It should be remarked that during this operation the hammer is raised in order that there nay be no impediment to the free passage of the powder up into the nipple. Then the hammer is lowered. Next the ball is introduced. A piece of cloth or patch of the right thickness is placed across the muzzle of the gun. 6 Sometimes this cloth is lightly greased with unsalted tallow. Often it is moistened with sputum immediately before using. The bullet is pressed through the cloth into the bore of the rifle, carrying some of the cloth with it, until the bullet is just below the end of the muzzle of the gun. Then the free ends of the cloth are gathered up in one hand and severed carefully with a knife. This leaves the ball in the barrel enclosed in a perfectly fitting cloth patch which enters and follows the grooves or rifles. The ball is pushed down the barrel onto the powder with the ramrod, care being taken that the barrel is vertical so that the powder lies horizontally in the bottom until the ball is pressed firmly but not vigorously against the charge.

One reads in some books that the bullet is seated by repeated heavy blows until the ramrod springs up from the ball some four or five inches. No intelligent rifleman would ever do this. If the ball is deformed by undue pressure of the ramrod it will not shoot true, After the ball is in place the lock or hammer is raised and a cap inserted on a nipple, when it is certain that a grain or two of powder can be seen at the tip of the latter. It should be remembered here that the hole in the nipple should be only large enough to permit a grain of powder to come to the top. If the hole is larger several things may happen. First, some of the powder may be lost during the loading operation. Second, when the cap explodes the enlarged hole of the nipple permits considerable back pressure of the powder and some of the force of the explosion is lost. And in the third place, if the hole in the nipple is too large and the spring actuating the hammer is weak, the hammer may be violently forced backwards with an explosion of burning powder from the nipple. On the other hand, if the hole in the nipple is too small, powder does not come to the tip of the nipple, and the piece misfires.

While it has been stated above that the majority of rifles made in the Great Smoky Mountains and by rifle-makers in general were sighted at 60 yards, these arms were formidable up to 200 yards. This was shown most strikingly in the Battle of New Orleans where some 6,600 rifle men from Kentucky, Tennessee, and the Carolinas, armed with the American rifle, utterly routed some 14,000 British troops, armed with smooth-bore muskets, who had fought under Wellington at the Battle of Waterloo. Some 1,900 British were killed or seriously wounded in the main action. The American casualties numbered only 13.

The muzzle velocity of these rifles with ordinary charges of powder is said to have been from 1,000 to 1,200 feet a second. lb expert hands, up to 100 yards they were remarkably accurate. Even today some of the mountain men of my acquaintance, old in years, somewhat dimmed in sight, can make targets at 60 yards which would be creditable on any rifle range.

This article was subsequently reprinted as NPS Popular Study Series #13.