Hard Hammer Research Articles

EMG study of hand muscle recruitment during hard hammer percussion manufacture of Oldowan tools

EMG study of hand muscle recruitment during hard hammer percussion manufacture of Oldowan tools

A Chip off the Old Block: Alternative Approaches to Debitage Analysis

A great diversity of approaches to the analysis of chipped stone debitage has been developed. This article explores the relative strengths and weaknesses of four different methods by applying them to the analysis of experimentally produced debitage. The mass analysis technique (cf. Ahler 1989) was found to be sensitive to reduction mode (hard hammer, soft hammer, pressure) and to overall stages of lithic reduction. It seems limited, however, in its capacity for detecting differences in core form and reduction strategy. Application of the four-component analytical scheme proposed by Sullivan and Rozen (1985) suggests that only one of the four categories (commonly referred to as shatter or non-flake debitage) possesses any marked technological significance. Striking platform and platform edge attributes appear to possess considerable potential for distinguishing aspects of coreform and reduction strategy. Metric attributes, by themselves, may not be ideally suited for detecting technological variation in debitage, but can be used to enhance the interpretations derived from other analytical approaches. It is concluded that no single method is uniquely suited to characterize the range of technological data that may be represented in chipped stone debitage. A battery of independent and mutually sup-portive techniques may provide the lithic ana-lyst with a more accurate and comprehensive perspective of archaeological flaking debris.

Vessey Ponds: a ‘prehistoric’ water supply in East Yorkshire?

Vessey Ponds are a pair of irregularly-shaped hollows high on the Chalk Wolds of East Yorkshire at about 220 m OD (Fig. 1). Recent fieldwalking recovered a large flint scatter in the vicinity of these hollows. Mesolithic activity was represented by worked flint displaying soft hammer technology whereas hard hammer technologies indicate Neolithic and Bronze Age tool production and usage. The presence of large numbers of cores and a vast quantity of industrial waste indicates on-site preparation of tools. Statistical analysis of the fieldwalking data implies that the flints are concentrated around the hollows. Auger sampling across the ponds revealed natural clay deposits that still hold water close to the pond surface. Consideration of exploitation of mineral resources on the Wold top and possible mechanisms of formation of Vessey Ponds highlights the complex effects of glacial activities on the local surface geology. Karstic origins for some features of surface geology are suggested. The nature of the ‘prehistoric’ economies represented by the flint scatter is considered along with ethnoarchaeological evidence to support the assumption that the ponds at Vessey were a potential water supply during the Mesolithic, Neolithic, and Bronze Ages. Evidence from Vessey Ponds and elsewhere in Yorkshire implies an association between areas of ‘prehistoric’ activity and the availability of surface water. Above all else, this work highlights the impact of water supply on settlement pattern and land use on the Chalk of the Yorkshire Wolds.

Dynamics of the pianoforte string and narrow hammers

A new method of solution to the equation of a perfectly flexible string, when struck at any point by hard or soft narrow hammers, is developed. The hard hammer is modeled as a point mass, and the soft hammer is modeled as a point mass backed by a linear or nonlinear spring and a dashpot, representing the compliance and dissipation of the felt. For each hammer the equation describing the string–hammer contact force during the periods of contact, and of recontacts, is derived explicitly. The Green’s function for a fixed-fixed string is represented by an infinite series of Heaviside functions. The analysis is exact in the spatial domain thereby eliminating modal truncation error and capturing all discontinuities in the contact force. The method predicts the contact force and system response under impacts given any hammer to string mass ratio that experiences any number of multiple contacts during the hammer strike.

An Evaluation of Debitage Produced by Experimental Bifacial Core Reduction of a Georgetown Chert Nodule

Controlled experimental reduction of a Georgetown chert nodule is used to evaluate the relationship of several discrete and continuous debitage attributes to the reduction sequence. The production of a bifacial blank using both hard and soft hammer percussion was the object of the experiment. Flake attributes are found to be strongly correlated with hammer type. The effects of switching hammer type during biface production complicate efforts to identify reduction stage from debitage assemblages. Discriminant analysis is used to remove the confounding effects of platform preparation flakes produced by small hard hammer percussion. Once these flakes have been removed from analysis, a discriminant function is defined which correctly classifies debitage at rates significantly greater than expected by chance assignment.

Piano string excitation III: General solution for a soft narrow hammer

As an important preliminary exercise for understanding excitation of real piano strings, the general solution for a point hammer of mass m hitting a perfectly flexible string of linear density μ is developed further by allowing for hammer compliance. Previous work on this problem is critically reviewed, and the existing analytic theory is summarized. The role of the critical compliance C0=m/16μT is discussed, and inclusion of a resistive force is also considered briefly. In close parallel with our earlier general solution for a hard hammer, the analytic solutions are implemented with a microcomputer to overcome the difficulties of multiple contacts between string and hammer, and representative results obtained by this method are presented. While this approach constitutes a general solution of the problem in principle, it is most practical for moderate values of the ratio of hammer mass to string mass and for C not too close to C0.

Elastic Impact of Pianoforte Hammer

This paper discusses the dynamical theory of the impact of a felt hammer upon a string at a distance α from one fixed end such that the reflected wave from the other distant fixed end does not reach the striking point during the time the hammer is in contact with the string. The Heaviside operational method leads to a solution in the form of a series consisting of incommensurable terms with damping coefficients increasing with the order of the term and tending to a limiting value. In the case of a hard hammer the damping coefficients decrease, and the terms are very much less incommensurable. These are the essential differences between the two cases that lead to smoothening down of the pressure and time curve between the hammer and the string in the case of a felt hammer.

XXIX.The theory of the pianoforte string struck by a hard hammer—Part I

XXIX.<i>The theory of the pianoforte string struck by a hard hammer</i>—Part I

The duration of contact between the pianoforte string and a hard hammer

The duration of contact between the pianoforte string and a hard hammer

XXXVIII.The duration of contact between the pianoforte string and a hard hammer

XXXVIII.<i>The duration of contact between the pianoforte string and a hard hammer</i>

XLVIII.Acoustics of strings struck by a hard hammer

XLVIII.<i>Acoustics of strings struck by a hard hammer</i>

LV.On the acoustics of strings struck by a hard hammer

LV.<i>On the acoustics of strings struck by a hard hammer</i>

LIII.On the Helmholtz theories of the struck string.—Part I.Theoretical

Summary The various theoretical treatments of the struck string are noted, and the Helmholtz theory for the hard hammer is then considered in detail, and is shown to be in conflict with experimental evidence. The Helmholtz theory for the elastic hammer is next considered, with the omission of two assumptions which caused Kaufmann to reject the theory. Expressions are found for quantities whose magnitude can be determined from photographically obtained displacement-time curves of the struck point. Expressions for the same quantities are derived from Kaufmann's theory of the string struck at the mid-point, and also from Kaufmann's approximate theory of the string struck near one end. The comparison of the theoretically and experimentally determined quantities is to be given in the second part of the paper.