from The Great Industries of the United States (1874)
THE INVENTION OF THE SCREW. — AN EXPLANATION OF THE SCREW. — MALE AND FEMALE SCREWS.—HUNTER’S SCREW. — MICROMETER SCREWS.—THE INTRODUCTION OF MACHINERY IN THE MAKING OF SCREWS.—THE FIRST MACHINE PATENTED IN THE UNITED STATES FOR MAKING SCREWS.—OTHER MACHINES INVENTED.— IMPROVEMENTS IN THE FORM OF THE SCREW.—THE GIMLET-POINTBD SCREW. — ITS PROBABLE ACCEPTANCE BY CONSUMERS.
[p.855] The invention of the screw is generally attributed to Archimedes, a philosopher of Syracuse, who flourished during the latter part of the third century before the Christian era. It is, however, most probable that the practical use of screws was known before his time, but that to him the credit belongs of having first classified the screw as one of the mechanical powers, and from the study of the laws regulating its action deduced the rule for calculating its efficiency.
A screw is evidently a special application of the inclined plane, and is made by the spiral revolution of an inclined plane about a fixed axis. Cut a piece of paper into the form of a right-angled triangle, the perpendicular side of which is of the length of the screw to be made, and the hypothenuse will represent an inclined plane. By simply winding this piece of paper about any object, as, for example, an ordinary lead pencil, the line of the hypothenuse will ascend in a spiral curve from the point to the top and represent the threads of a screw.
From the fact that the screw is a modification of the inclined plane, the method of its mechanical action is the same, and the power of the screw depends upon the ratio between the distance apart of the threads compared with the diameter of the circle they make in their revolution. As in practical mechanical applications the screw is generally combined with the lever, of course the power exerted is increased by the length of the lever, since the circle described by the power applied is increased by this distance.
The general division of screws is into male and female screws; the male screw being one in which the threads project upon the cylindrical body of the screw, and the female screw one in which [p.856] channels are cut for the reception of these threads. In the nuts and bolts in ordinary use, the bolts afford instances of the male, and the nuts instances of the female screws.
A combination of the male and female screw, in which great increase of power is gained, is that known as Hunter’s screw. In this arrangement, a screw working in a fixed nut is made hollow, with a female screw in the inside, along which a screw with finer threads works. The power exerted is as the difference in the distance between the threads of the two screws. While, of course, the power exerted by this arrangement is greatly increased, yet from the law of mechanics, that a gain in power is obtained by an expenditure of time, the motion produced is so small that this arrangement is not much used except when great weights are to be moved only small distances. The jack-screws which are used for raising houses or moving great weights are instances of one of the modifications of the Hunter screw.
This property, however, by which a considerable motion in the power is reduced to a very small motion in the weight, makes this combination of screws of great service in the manufacture of the philosophical instruments and in the accurate measurement of modern scientific research. By the use of micrometer screws, as they are called when devoted to such purposes, distances which are almost infinitesimal are measured with the greatest accuracy. With the microscope, objects wholly invisible to the naked eye are exactly measured to the many thousandth part of an inch.
The uses of screws in the various branches of modern industry areas innumerable as the variety of their sizes; ranging from the jack-screws, strong enough to raise enormous burdens, to those used in watch-making, which have to be applied with the microscope in order to enable the operator to see them with sufficient distinctness to discriminate which is the head and which the point.
The cutting of screws was, in early times, the chief difficulty in the way of their extensive production and use. As the process was then carried on entirely by hand, and required skill in making them with the desired accuracy, screws were too expensive to enter into very general consumption. With the advent, however, of the modern era of industry, in which the idea of the application of machinery to the various processes of manufacture, which forms so distinctive a characteristic of modern methods compared with those of antiquity, came to be practically applied, various attempts to produce screws by machinery were made.
[p.857] Soon after the formation of the Union of the States, and the establishment of a national system of patent rights, David Wilkinson, of Rhode Island, about 1794, applied for a patent for a machine for cutting screws. In 1789, Samuel Briggs, of Philadelphia, memorialized the Legislature of Pennsylvania and the General Congress on the subject of a machine for making nails, screws, and gimlets. In 1809, Abel Stowell, of Worcester, Mass., took out a patent for a machine for cutting screws; and in the same year Ezra l’Hommedieu, of Saybrook, Conn., patented a double-podded screw auger, and later in the year informed the Secretary of the Treasury that he made wire for himself, from which a man, aided by two boys, could make, by a process of his own, three hundred pounds a day of assorted screws, which were better than the imported ones, and that in his opinion in a short time the demand of the United States would be supplied by screws produced by his simple and cheap process.
In 1811, a machine for cutting screws was patented by Edward W. Carr, of Philadelphia, and put into operation by him in that city. In 1812, a patent for another machine for cutting screws was granted to E. Hazzard and Joseph White, of Philadelphia. In 1813, six patents were granted various parties for improvements in making screws by machinery. One of these was to Jacob Perkins, of Newburyport, Mass., for manufacturing the shanks of screws, and two others to Abel Stowell, of Worcester, Mass., for making and finishing the heads. In 1817, Phineas Dow and Daniel Treadwell, of Boston, Mass., patented a machine for making screws, which, from a coil of wire, cut, headed, grooved, polished, and finished screws at the rate of ten a minute, requiring only to be supplied with the wire, and have the end given to it.
In 1827, Lemuel W. Wright, of London, England, the inventor of a pin-machine, patented in this country a machine for making screws, which he had patented in England the year before. It was a considerably complex machine, and was superseded. In 1834, screws were first made by machinery at Providence, R. I., where the New England Screw Company, and another devoted to the same branch of manufacture, were organized within a few years, and commenced the production for which Providence has been distinguished up to the present time.
In 1852, four patents, and in 1856 four more, were issued to Cullen Whipple for improvements in making screws. These were assigned by him to the New England Screw Company.
[p.858] Not only have improvements been made in the machines for the production of screws, but also in the shape and method of constructing the screw itself. One of the chief of these is the introduction of the gimlet-pointed screw, which has almost entirely replaced the old-fashioned form of the screw ending in a blunt point. It seems singular that so simple an improvement as this, which is nothing but combining the screw point of the gimlet, which was formerly needed for making the hole in which the screw was afterwards placed, with the screw itself, should have been only so recently made; but any one who is aware of the slow course of improvement, both industrially and intellectually, which has heretofore necessarily marked the course of human advancement, from the want of a method which should scientifically direct the efforts of the human mind in these directions, and co-ordinate into a consistent system the scattered individual efforts towards the attainment of the means for producing the required ends which have so frequently proved abortive on account of their isolation, will not be surprised at it. The history of industry, among its numerous instances of this, affords perhaps none which is more striking than the above. Screws and gimlets had both been long in use before the idea of combining them together, simple as the idea seems, occurred to any one of the thousands daily engaged in practically using both of these implements, and this, too, when the gimlet itself was nothing but a pointed screw. And this is the more singular when we know that in France gimlet-pointed screws were made more than a hundred years ago, but, from the want of a simple change in the machinery used for making them, did not possess the accuracy needed for bringing them into general use.
The manufacture of the gimlet-pointed screws is chiefly done by the American Screw Company, of Providence, R. I., which is a consolidation of various New England companies formerly engaged in the manufacture of screws, and which controls their productions by the ownership of nearly fifty various patents for improvements in the processes of their manufacture, and by their consequently exclusive use of the best machines yet in use for this purpose.
The machines employed by this company are marvels of ingenious construction, and perform with rapidity and accuracy operations which would appear impossible to be performed by any other agency than skilled and intelligent manipulation.
The wire from which they are made is furnished in coils, and is [p.859] first dipped into acids, then annealed, and then drawn into the proper thickness. A machine then cuts the prepared wire into the required lengths, and cuts the heads of the shanks, at the rate of about ninety a minute. Then another machine shapes the heads of the screw, cuts the groove, and removes the burr. Then in another machine the threads are cut, and the gimlet point formed, at the rate of about five a minute. Then they are counted out by weight and prepared for sale.
The value of the screws produced by this company exceeds a million of dollars a year, and consists of about five million gross of screws, in the making of which over three thousand tons of iron are consumed, the chippings and trimmings from which amount to about three tons a day.
Another improvement in the method of making screws consists in the arrangement of the threads about the central cylinder. This invention was made by Mr. Samuel Pratt, who is at present a resident of Hammonton, New Jersey. This screw differs from the ordinary screw in having three threads, which revolve about the core only once and a half in their passage from the top to the point, instead of having, as in the ordinary screw, only one thread which revolves many times in the same distance. The advantage of having the threads revolve at this angle lies in the fact that a screw so constructed can be driven in with a hammer, instead of requiring a screw-driver. Under the blows of the hammer the screw in its passage through the wood revolves. Beside these merits, the simplicity of its construction renders it possible to manufacture them at a cheaper rate than other screws, and as the threads are further apart, and take a stronger hold upon the wood, it holds with nearly double the strength of an ordinary screw. With large bolts, such as are used for securing large timbers, — as, for instance, those of a ship, — the advantage of screws of this kind is very great. The patent for their manufacture has passed into the hands of a corporation, with a capital of two millions of dollars, the chief of whose establishments is at Northampton, Mass.
Although not yet as generally in use as the ordinary gimlet-pointed screw, from the recent date of their introduction, yet there is but little question that their superior claims to attention will be recognized in time by those who are interested in such matters.