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Swings and Roundabouts by Georg Rapp


The urge to make holes in things—a trait man shares with a surprising variety of animals, insects and even plants—provides the historian of technology with some of his most intriguing problems. And because it involves a basic manual skill, it offers some very good illustrations of the jumps, hesitations and blind spots that characterise technological "progress", the more so since the techniques of drilling would appear to have evolved almost everywhere with a minimum of what is called diffusion and a maximum of local invention.

Basic to the whole subject is the fact that man is an articulated animal, designed for reciprocating movements. Animate nature has no wheels.

Stated briefly, drilling began with twisting a sharp object to and fro from the wrist. The brad awl is the modern survivor of this primal technique. This pointed thing -- flint, bone, tooth or antler—was attached to a stick twirled between the palms of both hands; later a strap wound once round this stick might be pulled to and fro by one man while another held the top of the stick in a suitably socketed stone, bone or hardwood (by clenching this socket between the teeth, the strap drill could be turned into a one-man operation); then civilizations familiar with bows and arrows learned to use the bow to rotate the drill it has been suggested that an arrow was the first drill so used. There are suggestions that this bow drill—which in some areas evidently in some areas evidently coexisted with the strap drill for a long time—-hails from the distant Mesolithic, i.e. about 8000 B.C. It was in any event the dominant boring tool of antiquity.

The Egyptians had little or no knowledge of the auger (there is one somewhat questionable example in Flinders-Petrie). The pump drill came with the Romans—and the Archimedean was a contribution of the 19th century. (Some versions of it, with a continuous flywheel, are capable of continuous rotation.)

The auger, which allows considerable pressure to be brought to bear and made it possible to drill fairly large holes, may well be a contribution of the north. A fair number of iron bits survive from Roman days but the wooden handles have perished. W. L. Goodman, in a recent letter to me, now inclines to the view that these bits may have been used in bow drills, and that the T-handled auger reached the Romans when they encountered the Celts. If this is so, it leaves another fascinating delay to be explained, because this is a technologically simple idea requiring no sophisticated manufacturing techniques.

The auger became the dominant boring tool of the Middle Ages and after the 15th century it continued to share pride of place with the brace. In the absence of twist bits and lead screws (which, like the double iron and the standardization of the length of the moulding plane, appear to be products of the late 18th century), it may have needed pilot holes drilled by awl, brace or simply a smaller bit. Spirally twisted pod augers with a sort of screw action are, however, found already in the 16th century.

This schematic development of boring was not everywhere or anywhere necessarily in that order. Technological progress is a wayward business. Some cultures (Egypt) had a pottery wheel long before the cart wheel. In northern Europe it was the other way round. (The one possible exception to all this is the famous Egyptian drill, unevenly weighted near the top by two bags of stones tied on opposite sides and surmounted by what looks like an eccentric handle. V. Gordon Childe, in his essay on continuous rotary motion in the Oxford History of Technology, discusses and rejects the possibility of its having been used in a crank-like fashion, but Prof. Hartenberg has suggested that such an instrument—he experimented with a possible reconstruction—once set spinning could be kept continuously rotating by a to and fro motion applied to the handle. This can be done with, for instance, an Ultimatum in good condition although little pressure can be applied to the bit. The Egyptian drill, if used in this way, may have relied on the weight of the stones and was used to abrade stone by friction, probably with a grinding agent such as sand. Both J. Needham, the historian of Chinese technology, and W.I.. Goodman appear to share some or all of Prof. Hartenberg's assumptions, but Goodman agrees that this was "a sort of by-blow". If this was a case of drilling by continuous rotation, it produced no technological spin-off.)

What all these considerations lead up to is the astonishing fact that—as far as present knowledge goes—the crank, and even more so the double crank with two bearings as in a carpenter's brace completely eluded inventive man for something like 4000 years after the invention of the wheel. (In China this curious delay may have been about loon years shorter: the wheel may have got there just a little later and the first crank is thought to have turned up there, as the handle of a winnowing fan, on a Han pottery model, at about the beginning of the Christian era).

What I am asking you to consider is that when men who were familiar with wheels, with lever, screw (outside China), wedge, pulley and winch, cogwheels and gearing, and with the maintained momentum of the potter's wheel, put their own hands to anything to turn it, they moved them to and fro or hand over hand. Animal power was freely used to provide continuous rotary motion for grinding mills while the women working their stone handmills known as querns jerked the handles, lateral or vertical, backwards and forwards. This apparent absence of crank motion also meant that there was no simple means of conver tiny reciprocating and rotary motion into each other.

We take the crank so much for granted nowadays that this odd delay long escaped notice, and some historians still find it difficult to accept, the more so since the crank, single or double, would have required for its construction no technology that had not long been available. Thus museum "reconstructions

still tend to project the crank backwards into ages when it was unknown. There is no unambiguous archaeological, pictorial or literary evidence of it in the West until it turns up on a rotary grindstone in the Utrecht Psalter in the early 9th century.

This becomes of sudden interest to the tool collector when it is realized that the carpenter's brace was the first instance of a double crank to appear. Historians are divided as to whether the camshaft or the double crank should rank as the major medieval contribution to technical advance. In the context of an Arnold ~ Walker catalogue we must surely opt for the unknown, perhaps even illiterate Flemish carpenter, who had this sudden inspiration early in the 15th century when the first brace appears in paintings. (About a century earlier the Italian Vigevano had designed paddle boats using double cranks but they never got off the drawing board.) The brace was recognised so rapidly as a means of turning reciprocating motion into rotary motion and vice versa that connecting rods, flywheels and crankshafts appear almost instantly. In fact the evidence seems a little confusing. Some illustrations indicate that the brace was at first misunderstood by some. thus tending to show that the idea was new and unfamiliar. But other pictures show perfectly adequate applications so soon afterwards (cf. Samson at the Mill, Visconti Hours, LF158v) and the first picture of a brace itself represents so well made and well finished a brace that one is tempted to assume a somewhat longer, as yet unknown pedigree. Tool collectors, particularly in the United States, will be familiar with many rough and primitive braces, hinting at a descent from a convenient bent branch. The earliest known brace illustration shows a finely made specimen, with a neatly turned upper knob and carefully chamfered throw. In fact, Goodman holds that the first illustrated brace "is probably just the tip of a very large iceberg".

It is worth considering that at the very beginning of the Renaissance, men had, in a sense, the basic elements of the modern motor car: wheels, guns and braces for what, except for needed advances in metallurgy and fuel chemistry, is the car but four guns firing into four braces to drive four wheels?

So when you next pick up a carpenter's brace, you may like to remember that the carpenter who stumbled upon this beautifully simple but so long elusive idea did much more than facilitate the boring of holes: he triggered off a major spurt in technological advance. To readers intrigued by this wider aspect of humble tools I would recommend Mediaeval Technology and Social Change, by Prof. Lynn White, Jr., to whom I owe many of the ideas I have outlined. For a general survey of the history of boring tools there remains the as yet unequalled History of Wood working Tools, by W. L. Goodman Esq.

It is almost irresistible to speculate on why crank and double crank were so long delayed and why they finally turned up when they did. It is known from studies on the development of children that there is an early resistance to crank motion, which evidently requires an advanced stage in the maturation of nerve pathways and muscular coordination. The crank may finally have reached the West from China, but there is a temptation to imagine that in fact the rotary grindstone "invented" it. If some peasant or artisan seeking to sharpen a blade stumbled upon the abandoned topstone of a quern, with its convenient central hole, might he not have thought to hang it vertically, like a cartwheel, upon some peg or other axle, and then have found that the natural momentum of the stone, its flywheel effect, resisted to and fro motion and kept swinging in one direction, with less effort than would be needed to keep braking and reversing its impetus? By the time the brace was invented, cranks and double cranks were "in the air".

The history of hole making has other puzzles. One of them goes back to the earliest days when men laboriously ground holes in stone hammers or axes to take a handle sometimes with quite advanced tubular drills which considerably reduced the area to be ground away. In the examples we have, these holes are often bored from both sides and almost invariably meet beautifully in the middle. Those who have tried to do this with modern tools in wood will appreciate the skill involved. As V. Gordon Childe put it, "In most cases the accuracy is so astonishing that some centering device is usually postulated, and elaborate drilling machines have been imagined, providing both centering and downward pressure on the spindle. Such reconstructions . . . are completely imaginary."

Bearing Mechanisms

Mr. Rapp's stimulating essay draws attention to the remarkable status of the carpenter's brace as the first practical application of the double crank principle, but he stops short of considering the factors which make crank such a significant advance over the single crank.In machinery the contribution of the double crank to balance and reduction of wear are obviously important but in the brace itself it is the facility of applying end-pressure which characterises it. If we compare the brace to the automobile starting handle (for those of us old enough to remember such things! ), and imagine ourselves trying to push the car backwards at the same time as we wind the motor, we see the benefit of being able to throw the weight of the body on to the brace head. A similar consideration applies in the matter of tension, i.e. the ability to pull the bit back out of the hole. The methods employed for dealing with such pressure and tension, prior to general use of bearings and the Barber shell-chuck, make a useful basis for the classification of braces and boring tools.A single point bearing is more efficient, and simpler, than that where the pressure is spread over the larger circumference area of a seating. It is also by far the older system, being the basis of the strap and bow drills. It isd exemplified in this catalogue by the simple bow drill No. 53 and brought to the peak of perfection with the adjustable internal bearing of No. 47. However, the extraordinary fact is that most braces rely on the circumferential seating and that this principle has been the subject of numerous special designs, some of great complexity and illustrated in Figures 1-4.

A relatively simple design of this sort is the William Marples Ultimatum (see Nos. I, 2 and 243) illustrated in Fig. I. The friction pressure is taken between the brass baluster neck and the seating around the spindle. Play can be taken up by inserting additional iron washers, but, since these are harder than the brass seating, wear is apt to be considerable. Another comparable design is Joseph Cooper's (No. 10), illustrated in Fig. 2. Here the friction is spread over a very large area of brass but the curved shapes must have been difficult to manufacture without having the even seating properties of true cones.

Fenton and Marsden's design, registered in 1847 (No. 12 and Fig. 3), is something of a solution since the thrust is, or can be, taken on the end of the spindle as well as on the circumference although, even then, there was no attempt to bring the bearing to an actual point. A highly elaborate divided steel collar mechanism is included to deal with the withdrawal tension.

The one mechanism which relies entirely on the centrepoint bearing is "John Bottom's Invention" (No. 15 and Fig. 4), which we believe was introduced in about 1840, thus pre-dating the other mechanisms illustrated. It is incorporated in No. 15, by Henry Brown & Sons, Sheffield 1850 1900.

This article on braces was copied from an old Arnold and Walker catalog. Arnold and Walker were British tool dealers. The drawings are by Matthew Carter.